Crash Absorption Structure for Formula Ford Use of ROHACELL in Motorsport Crash Worthiness Bryan Chu Oliver Jetson Neal Parkhurst Sébastien Pinauldt Jorre Valeart Cranfield University MSc in Motorsport Engineering & Management March 2007

Abstract

Build an economical frontal crash structure which may be used in the Formula Ford series. Thestructure must meet three test conditions: a static crush test, a push off test, and a dynamicsled impact. There are no limitations on the materials used in the construction of the crashstructure but the manufacturing costs must be kept under £400. The size limitations are asdetermined by the regulations in the Formula Ford series.

Acknowledgements

There are many people who we would like to acknowledge for their support over the months forthis project.

Firstly we would like to thank Mr. Steve Wills, Mr. Keith Lain and the employees of SpiritRacing Cars, for their guidance and use of facilities throughout.

Many thanks to Axel Zajonz from Degussa for providing the Rohacell material.

A special thanks to Mr. Jim Hurley and Dr. Denis Cartie from the Cranfield Universitycomposites department for their advice and expertise with manufacture and testing.

For their support during the testing period we are greatful for the assistance of Robin Butler,Tony, Clive, James and Ralph from the Cranfield Impact Centre.

We also acknowledge the help of Mrs. Kirsty Montgomery, Mr. John Nixon, Dr. Jeffrey Alcock,Mr. Tony Lawrence and Mrs. Sharon Mcguire, all of Cranfield University.

Contents

1 Introduction 6

2 Objectives 7

3 Background Research 8

3.1 Driver safety within other formulae . . . . . . . . . . . . . . . . . . . . . . . . . . 8

3.2 Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

4 Design 9

4.1 Overall Design Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

4.2 Initial Evaluations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

4.2.1 Energy and Forces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

4.2.2 FEA and PAMCRASH . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

4.2.3 Initial Design Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

4.3 Aluminium Honeycomb . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

4.4 Rohacell . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

4.4.1 Preliminary Performance Analysis . . . . . . . . . . . . . . . . . . . . . . 14

4.4.2 Analysis of Rohacell Crush Structure . . . . . . . . . . . . . . . . . . . . . 16

4.4.3 Adhesives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

4.5 Secondary Bulkhead . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

4.5.1 Analysis of Secondary Bulkhead . . . . . . . . . . . . . . . . . . . . . . . 22

4.6 Final Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

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4.6.1 Prototype Secondary Bulkhead . . . . . . . . . . . . . . . . . . . . . . . . 28

4.6.2 Final Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

4.6.3 Manufacturing Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

5 Testing 34

5.1 Original Crash Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

5.1.1 Modifications Carried Out For Testing . . . . . . . . . . . . . . . . . . . . 34

5.1.2 Static Crush Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

5.1.3 Results of Testing Original Structure . . . . . . . . . . . . . . . . . . . . . 36

5.1.4 Conclusions Of Testing Original Structure . . . . . . . . . . . . . . . . . . 37

5.2 Final Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

5.2.1 Static Crush Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

5.2.2 Side Push Off Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

5.2.3 Front Impact Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

6 Conclusion 51

A Secondary Materials 53

A.1 Skin Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

A.2 Core Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

B Preliminary Testing 57

B.1 Rohacell . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

B.1.1 Static Crush Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

B.1.2 Impact Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

C Manufacturing Costs 61

2

List of Figures

4.1 Energy and Forces of Impact . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

4.2 Newton’s Second Law for an Average Acceleration . . . . . . . . . . . . . . . . . 10

4.3 Specific Energy Absorption of Rohacell . . . . . . . . . . . . . . . . . . . . . . . . 15

4.4 Compaction Percentage of Rohacell Grades . . . . . . . . . . . . . . . . . . . . . 15

4.5 Simplififed Rohacell Nose Cone Structure for FEA Optimisation . . . . . . . . . 17

4.6 Loading and Constraint Boundary Conditions for Rohacell Structure . . . . . . . 18

4.7 Rohacell Structure with a 20 mm lip Loaded at 30 kN . . . . . . . . . . . . . . . 19

4.8 Rohacell Structure with a 90 mm lip Loaded at 30 kN . . . . . . . . . . . . . . . 20

4.9 Rohacell Structure with a 115 mm lip Loaded at 30 kN . . . . . . . . . . . . . . 20

4.10 Rohacell Structure without side lips Loaded at 30 kN . . . . . . . . . . . . . . . 21

4.11 Initial Design of Secondary Bulkhead before Optimisation . . . . . . . . . . . . . 23

4.12 Analysis of Initial Design: 1.5 mm wall thickness, 167kN distributed on topplate,constrained at base of feet, and 5mm solid tetrahedral elements . . . . . . . 23

4.13 1/4 Model with Symmetry Boundary Conditions . . . . . . . . . . . . . . . . . . 24

4.14 Analysis on Revision 1 Design of 1/4 Model: 2 mm wall thickness, 167kN dis-tributed on top plate, constrained at base of feet, 5mm solid tetrahedral elements 25

4.15 Analysis on Revision 2 Design of 1/4 Model: 2 mm wall thickness, 167kN dis-tributed on top plate, constrained at base of feet, 1.5mm solid tetrahedral elements 26

4.16 Localised Mesh Refinement at Edge of Triangular Braces . . . . . . . . . . . . . . 27

4.17 Analysis on Revision 3 Design of 1/4 Model: 2.5 mm wall thickness, 167kNdistributed on top plate, constrained at base of feet, 1.5mm solid tetrahedralelements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

4.18 Prototype Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

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4.19 Final Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

5.1 Spirit Crush Structure Prepared for Testing . . . . . . . . . . . . . . . . . . . . . 34

5.2 Spirit Crush Structure Before Static Crush Test . . . . . . . . . . . . . . . . . . . 36

5.3 Spirit Crush Structure After Static Crush Test . . . . . . . . . . . . . . . . . . . 36

5.4 Original Spirit Crush Structure Static Load Test . . . . . . . . . . . . . . . . . . 37

5.5 Cracking of Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

5.6 Static Crush of First Full Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

5.7 Static Crush of Second Full Size Structure . . . . . . . . . . . . . . . . . . . . . . 40

5.8 Crushing of Scaled Down Model . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

5.9 Static Crush of 70% Scale Structure . . . . . . . . . . . . . . . . . . . . . . . . . 41

5.10 First Attempt at Push Off Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

5.11 Moments Before Structural Failure at a Load of 16.2kN . . . . . . . . . . . . . . 43

5.12 Remains of First Push Off Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

5.13 Second Attempt at Push Off Test . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

5.14 Top View of Crack in the Foam Structure During Second Push Off Test . . . . . 46

5.15 Placement of Pad in Third Push Off Test . . . . . . . . . . . . . . . . . . . . . . 46

5.16 Translation of Side Tabs in Push Off . . . . . . . . . . . . . . . . . . . . . . . . . 47

5.17 Sled with Final Test Model Mounted . . . . . . . . . . . . . . . . . . . . . . . . . 48

5.18 Resulting Data From Dynamic Test . . . . . . . . . . . . . . . . . . . . . . . . . 49

5.19 Early Failure of the Material at 17 ms After Impact . . . . . . . . . . . . . . . . 50

5.20 Additional Loss of Material at the Base at 46 ms After Impact . . . . . . . . . . 50

B.1 Static Crush on a Sample of Rohacell 110IG, ø79 mm . . . . . . . . . . . . . . . 58

B.2 Drop Test on a Plain Sample of Rohacell 110IG, ø80 mm . . . . . . . . . . . . . 59

B.3 Drop Test on a Bonded Sample of Rohacell 110IG, ø76 mm . . . . . . . . . . . . 59

B.4 Collection of Rohacell Samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

4

List of Tables

4.1 Properties of Rohacell . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

4.2 Bill of Materials for Prototype Structure . . . . . . . . . . . . . . . . . . . . . . . 31

4.3 Bill of Materials for Final Structure . . . . . . . . . . . . . . . . . . . . . . . . . 31

4.4 Total Cost to Produce a Prototype Structure . . . . . . . . . . . . . . . . . . . . 32

4.5 Total Cost to Produce a Final Structure . . . . . . . . . . . . . . . . . . . . . . . 33

4.6 Summarised Total Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

4.7 Volume Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

A.1 Properties of aluminium against other materials . . . . . . . . . . . . . . . . . . . 53

A.2 Properties of different glass fibre reinforcements against other fibre materials . . 54

A.3 Comparison of carbon fibre properties against steel . . . . . . . . . . . . . . . . . 55

A.4 Types of carbon fibre . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

A.5 Properties of Kevlar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

5

1 Introduction

Cranfield University in cooperation with Ford[12] and the governing bodies of motorsport,namely the FIA[7] and the MSA[9], seek to develop the regulations of space frame chassis on aworldwide level. In part to provide a set of standards for the safety of drivers in the numerousFormula Ford series around the world, and additionally by creating a world recognised set ofregulations, Formula Ford can be introduced to new countries without the concern of creatingentirely new governing bodies. In the past there has not been any kind of common regulationsamongst the different Formula Ford series, and has been running in this method for a numberof decades.

The transition from the currently unregulated to a regulated state will not be an easy onefor Formula Ford to take on, and our part is only a small portion. This project will involveexamining the front crash structure used to protect the driver in the event of a frontal impact. Atthe moment every manufacturer has a different method of producing their crash structure, andnone of these designs have been officially tested. Freedom is given to the student design groupsto develop a new crash box which will be tested against a set of impact requirements whichhave been based off similar tests used for Formula 1 and Formula 3. The end result of thesenew designs may be used as new structure which will be common amongst all manufacturers.Ultimately the final product of the project should be a crash structure which can survive theseimpact tests and be suitable for the low-budget mindset of the Formula Ford series.

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2 Objectives

Produce a crash structure which will pass the following tests:- Static Crush Test- Side Push Off Test- Front Impact Test

The hopes are that by performing these tests we can have a baseline as well as a comparisonbetween different designs which will lead to improved driver safety in a front impact situation.Further details about the testing procedure are outlined in Section 5

The final construction costs of the crash box should not exceed £400 in keeping with thespirit of the low cost racing series. In addition, we felt that majority of the structure, if not allof it should be something that our manufacturer, Spirit, could produce in-house.

The groups will also have to generate a report which will detail the design, manufacture andtesting of the crash structure.

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3 Background Research

3.1 Driver safety within other formulae

The greatest restriction to this project will be the limitation on the cost. The Formula Fordseries is structured as a low-cost series to permit the greatest number of entries. In comparison,other series ranging from Formula 1 to Formula Renault typically use a carbon fibre monocoque,have larger budgets, and already have a set of regulations to govern them. In following withtheir carbon fibre monocoques their noses are essentially carbon fibre tubes made from sandwichmaterials of nomex honeycomb. These differences enable the manufacturers and teams to usemore exotic materials and testing methods to ensure the crash structures will protect theiroccupants. The goal is to bring this same level of safety to Formula Ford without causing strainon team budgets.

3.2 Materials

There is a wide variety of materials that could have been used for building the crash structure.The main materials which we focused on include aluminium honeycomb and polymer foamswhich will be detail below. There was additional research into other materials listed in AppendixA, these were gradually ruled out during our design selection process.

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4 Design

4.1 Overall Design Requirements

In order pass these crash tests some basic goals must be achieved. The initial static crush testwill strictly be used to ensure that when the crash structure is attached to the dynamic sled thatit will absorb a sufficient amount of energy such that the testing equipment is not damaged.

The second test will be an important means of evaluating these newly developed crashstructures because the attachment points of the current nose boxes amongst all manufacturersis seen as a severe weakness. In our research through examining past cars, speaking to teamsand manufacturers there has been a consensus that though the structures themselves may beable to absorb some amount of energy in a crash there is a tendency for the nose section to beeasily detached before it has the opportunity to take part in the impact. That leaves us witha critical issue of creating attachments which are strong enough to pass the specified push offtest, but also allow access and easy removal for servicing.

Finally the last test will be to determine if the new crash structure can absorb enough energyin a dynamic test to slow the impact and limit the g-forces transmitted into the chassis. Thedetails of the mechanism for energy absorption are described below.

4.2 Initial Evaluations

4.2.1 Energy and Forces

During the crash, the kinetic energy is converted into a ”crush” work, the amount of workenergy put into a crushing load along the crush distance Lcrush.

Taking Vo as the initial speed provided by the testing regulation, and assuming the finalspeed is zero we have ∆V = Vo. Also taking from the testing regulations we have a test massm. A straightforward energy calculation using the following equations, also demonstrated inFigure 4.1:

1

2· m · ∆V 2 = Ecrush (4.1)

Ecrush = Wcrush = Lcrush · Fcrush (4.2)

Where Ecrush is the energy to be absorbed by the structure, Wcrush is the amount of work doneon the structure, Lcrush is the length over which the crushing takes place, and Fcrush is theforces performing the work.

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Figure 4.1: Energy and Forces of Impact

During the crushing of the structure we have our Fcrush, from Newton’s Second Law andusing an average acceleration a we get:

Fcrush = m · a (4.3)

Figure 4.2: Newton’s Second Law for an Average Acceleration

Since we have our prescribed mass of 595kg and maximum acceleration of 25g we can workbackwards to determine the forces involved and the required size of our structure. So fromEquation 4.3:

Fcrush = 595kg · 25 · g = 595kg · 25 · 9.81m

s2= 146kN (4.4)

If we take a margin on the value for maximum acceleration and choose 23g we have instead:

Fcrush = 595kg · 23 · g = 595kg · 23 · 9.81m

s2= 134kN (4.5)

Moving on to Equation 4.1 and 4.2 we can solve for Lcrush giving the following:

Lcrush =Ecrush

Fcrush

=1

2· m · ∆V 2

m · a(4.6)

Using the calculations from above and our test velocity of 12 m/s:

Lcrush =(12m

s)2

2 · 25 · g= 293mm (4.7)

Lcrush =(12m

s)2

2 · 23 · g= 319mm (4.8)

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So we see that in order to impact with a lower average acceleration from the same initialvelocity we will require a longer structure over which to absorb the energy in the impact. Thenext stage is then to find a material which crushes at the forces calculated above and whichwill fit within the length available within the current nose cone. Some of the materials we areconsidering, such as honeycomb, have their characteristics listed as a load pressure, so we haveto relate our force to pressure via the cross sectional area of the structure.

Fcrush = Pcrush · S (4.9)

Where Pcrush is tabulated in the manufacturer’s data sheets and S is the cross section of thenose structure, similar to the length of the structure this area is governed by the dimensions ofthe nose cone.

4.2.2 FEA and PAMCRASH

As with many current design processes there is a great desire to run simulations and virtualtests before committing the resources to building and testing an actual product. We attemptedto do the same, to have a better understanding of how some of these potential materials maybehave under our test conditions. Finite Element Analysis (FEA) is commonly used, but it hasa limitation in this situation because it assumes a quasi-static equilibrium just the same as weperform our static crush test and may not generate accurate results. The best case would beto use a dynamic code such as those provided by PAMCRASH or LS-DYNA. We began sometraining seminars to learn how to use PAMCRASH, but unfortunately the professor involvedin instructing us left the university shortly thereafter. In addition, students who had somefamiliarity with the programs were also unavailable to help as they were all completing theirdissertations. So, due to the limited resources on hand we were never able to fully utilise theseprogram to evaluate our material selection. Instead we would have to rely on FEA and testingsamples of the materials and extrapolate the overall behaviour.

The accuracy of the results generated by any FEA software package is directly related tothe number of elements used for analysis, and this is also directly related to the calculation timerequired for the analysis to converge to a solution. It is generally accepted that in the earlystages of a model’s analysis, a coarse element mesh can be used to generate fast results andidentify the effect of changes made, and that when the design is more finalised the mesh can berefined, either in specific areas of interest or across the whole model to increase the calculationaccuracy.

Many software packages are available to carry out finite element analysis, either in the formof dedicated FEA programs or in the form of FEA solvers within existing 3D CAD software. TheFEA software used for all analysis of the Secondary Bulkhead and the Rohacell Crush Structurewas the integral solver within the 3D CAD system I-Deas. This software was selected because itallows detailed generation and inspection of the element mesh and also allows modification andrefinement of the mesh in areas of interest. The results of the individual components simulatedwill be detailed in their respective sections.

4.2.3 Initial Design Selection

An initial collection of design options generated approximately 20 different choices. Theseoptions are not necessarily exclusive of each other, but we needed some method of rankingthem to try to isolate them. We then created a list of requirements, our ”Musts”, for the design

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which were typically governed by our regulations. The materials could not be affected by water,our perception of the cost would have to be within the allotted £400, and it had to providesufficient energy absorption. Certainly our judgement of these options was not exhaustive andrather subjective as we did not have the time or capacity to test and accurately evaluate all thesematerials and designs. We used our best judgement to narrow our selection. After checking our”Musts” the result was 12 options, so the next filter was to give them a ranking on how theymet some desirable traits, our ”Wants”. These traits included things such as how easily thematerial can be worked into the required shape using standard tools or how readily available thematerial might be. Again this is a rather subjective listing, but given our resources it seemedto be a good starting point. The end result was a group of 5 choices which seemed to revolvearound the idea of utilising a skin made of aluminium to house a block of energy absorbingmaterial such as an aluminium honeycomb or foam placed on top of a secondary bulkhead toallow for attachment to the chassis around the existing master cylinders and steering rack.

At the time of our initial analysis we had ruled out composites due to their difficulty ofmanufacturing and in trying to keep to our philosophy of designing within Spirit’s produc-tion capabilities. However, this decision was made with our composite knowledge limited toprepregs and autoclaves. After some more recent experience it seems that it may be possibleto use a vacuum infusion process to create composite structures without necessarily requiringan autoclave.

4.3 Aluminium Honeycomb

Honeycomb materials are commonly used in sandwich structures and can provide a great dealof strength in a relatively lightweight structure. However, there are a few design considerationswhen working with the honeycomb. One factor is the resulting shape and orientation of theindividual cells within the core section of the material. As opposed with other bulk materialssuch as with most metals and even with foams, their behaviour is generally isotropic whereashoneycombs have a very defined directional strength. The strength of the honeycomb can betailored to a specific application by the choice of cell sizes as well as the cell wall thickness. Thisresults in a value for the overall density of the material, and when talking to manufacturersthey will reference their materials by this density as this will govern the cost of the material. Sowe have determined that the strength of the honeycomb in the axial direction would work welland could be adjusted to suit our needs, but this leads to concerns about the strength in theother directions namely the lateral strength in order to withstand our side push off test. If weplan on using the honeycomb it would have to be oriented longitudinally with the cells parallelto the centerline of the chassis, and additional reinforcements would have to be incorporated tosupport the lateral loads.

Another property of the material to be concerned with is how the cells compress. If weconsider a single tube under compression, there is a peak force which is required to initiatethe collapse of the remainder of the tube. This peak force causes a spike in the loading whereas the bulk of the tube under compression is a steady load. A similar issue applies to thehoneycomb structure where each cell has a high initial peak load before leveling off to a stablecrushing load. In addition to the problem of the spike, the side which begins the collapse can beunpredictable which is an undesirable trait. The typical method of circumventing this problemis to incorporate a pre-crush into the honeycomb by weaken and crushing a smaller percentage ofthe cell on one side of the material. This pre-crush makes the compression behaviour much morepredictable and repeatable, unfortunately purchasing the honeycomb pre-crushed increases the

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price.

In order to relate the specifications about the different grades of honeycomb we have to goback to our initial calculations in Section 4.2.1 and decided on the surface area available touse. As previously described it would be the internal dimensions of the nose cone as well asthe surface of the secondary bulkhead that governs the size of the structure. As a preliminarydesign, we measured the internal dimensions of the nose cone and assumed an offset of 150 mmfrom the main frame bulkhead to accommodate for the master cylinders and our secondarybulkhead. This gave an average frontal cross sectional area of 0.030m2 for the space occupiedby the material. Using Equation 4.9 we determine with our 23g average acceleration that thematerial must withstand a specific load of 4.5 MPa (650psi).

We contacted a few different aluminium honeycomb suppliers and manufacturers such asHexcel[8] and Plascore[10], and the appropriate range results in honeycomb cells either 1/8or 3/16 of an inch across and a cell thickness of 0.002 in. or 0.0015 in. respectively. Upondiscussing the pricing we discovered that in order to get the correct amount to fill out structurethat the price for pre-crushed material was quickly approaching our £400 limit, and we had notyet begun dealing with additional support for the lateral tests. The non-pre-crushed materialwas more reasonable at about half the price, but this would incur additional labour costs if wewere to crush it ourselves for the best performance. However at the same time, research wasbeing done on other materials such as polymer foams and they were starting to show promise,so we abandoned our option to build out of aluminium and focused on a polymer foam structureinstead.

4.4 Rohacell

As mentioned above we have investigated the use of polymer foams as our energy absorptionstructure. Most of them are much too weak but this does not make them invalid because thereare a select few which are designed for high performance applications which we may be able touse to our advantage.

One company, Degussa[6], sells a range of very high strength polymethacrylimide (PMI)foams under the name Rohacell[11]. The Rohacell-WF range is available in a range of compres-sive strengths from 0.8 MPa all the way up to 15.8 MPa. As calculated above we are aiming fora material whose compressive strength lies between 3.5 MPa and 5 MPa, so this range seemedto fit well. The material itself has typically been used as a core material for producing com-posite sandwich structures and as such has never been fully tested for use as a bulk material inthis manner. However, after talking with a representative from Degussa it was suggested thatperhaps their IG series would be a better choice as it is still close to our required compressivestrength range and would be more economical.

The benefits of Rohacell is its homogenous cell structure and isotropic properties. Thebiggest drawback is that because of its production process, its current form is only produced insheets. Various grades are available as various densities. We only focused on the lowest grade(IG) as we do not require special properties in terms of heat resistance and resin processing,which would utilise the higher grades. The material’s static behaviours are also favorable, it iseasy to cut with simple hand tools or can be placed in a mill. The manufacturer also suggeststhermoforming of parts, although that process is probably more suitable to larger productionvolumes.

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In terms of crushing, before performing any tests, the only known value was the compressivestrength, which we assumed to be identical to the steady crush strength. This was a largeassumption but considering the crushing mechanism of foam, it would make sense. A studytesting lower density foam confirmed that the behaviour is very steady until full compaction.[13] During crushing a very clear plateau can be observed in the load vs. displacement curve.The average load of the plateau corresponds well to the compressive strength value given inthe manufacturer’s datasheets. Further testing on samples of Rohacell demonstrated a similarbehaviour, see Appendix B.1 for our test results.

4.4.1 Preliminary Performance Analysis

In regards to the assumption explained previously, we specified a preliminary design in order topass the tests, similar to the preliminary design of the aluminium honeycomb structure, withthe required values of energy absorption, acceleration and side load.

The first parameter to evaluate is the energy absorption capability of the foam. Using thecompressive strength value (in MPa), keeping in mind our assumptions, we can calculate atheoretical value for the Volumetric Energy Absorption (VEA) in kJ/m3. If the compressivestrength is 3MPa for instance in the case of Rohacell 110IG, the theoretical VEA will be 3000kJ/m3 for a block of 1 m3. A more interesting value is the Specific Energy Absorption (SEA)given by units of mass in kJ/kg which takes into account the foam density.

Density (kg/m3) Compressive Full SEA (kJ/kg)Strength (MPa) Compaction (%)

Rohacell 31 IG 32 0.4 75 9.38Rohacell 51 IG 52 0.9 71.3 12.34Rohacell 71 IG 75 1.5 67 13.40Test Samples 96.5 2.36 63 15.43Rohacell 110 IG 110 3 60 16.50

Table 4.1: Properties of Rohacell

There is a strong correlation between SEA with the density. We would then prefer thehighest grade, Rohacell 110IG. However, this advantage in terms of SEA might be balanced bya greater remaining length after full compaction for the higher density materials, which is alsofunction of the density as seen in Figure 4.4.

Note that the figures of full compaction length are the result of a rough interpolation betweenthe results available for Rohacell 31 IG and our test samples.

In our case, we did not take into account the difference in the compaction length becausethis difference is relatively small compared to the difference in SEA, and we would much preferto have the improved SEA at the sacrifice of some length. However this sacrifice is non-trivial,the space available in the nosecone is a constraint especially having made the choice to use asecondary bulkhead to fit the master cylinders, anti-roll bars and steering rack.

As seen previously from the hand calculation, the average acceleration value gives us a valuefor the length over which the vehicle is going to stop. We will often refer to this length as”crushing length”. The results gave a 293mm crushing length. Therefore the overall length

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Figure 4.3: Specific Energy Absorption of Rohacell

Figure 4.4: Compaction Percentage of Rohacell Grades

should be 489mm considering 40% as the residual length after compaction. The actual modelwill in fact be 500mm long which allows for some contingency in terms of acceleration.

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However, after testing our samples we have found that the crushing loads that the materialcan handle is slightly lower than expected. In order to compensate for this drop we decidedto make the volume of material larger than first predicted and as such the base surface areaof the secondary bulkhead is also increased over the initial assumed values although the lengthremained the same as it was restricted by the nose cone.

4.4.2 Analysis of Rohacell Crush Structure

It is a requirement of the crush structure to withstand a side load of 30kN applied by a 100mmx 300mm pad at a point 400mm from the front axle centre line. For this test requirement to bemet it was necessary to ensure that the Rohacell nose cone and its attachment to the secondarybulkhead would not fail during this loading. As previously mentioned one of the benefits ofusing Rohacell is its isotopic properties which could allow us sustain high off-axis loads. In thisfollowing section we will try to evaluate the lateral performance through hand calculations andFEA of the bare foam without any outer skin reinforcement.

The first criteria to be examined is the pressure being applied under the pad during the pushoff test. With the tapered shape of our nose, the area under the pad is approximately 0.017 m2

and the load being applied is 30 kN which results in a pressure of 1.77 MPa. If we compare thiswith the compressive strength of the foam of 3 MPa, it is clear that the pad pressure shouldnot be a problem.

The more critical criteria is the foam’s resistance to the bending moment being applied.In order to get a basic sense of the result we kept the calculations simple, and used a beamtheory to determine the shear and normal stresses. It should be noted that the beam theory inthis particular case is outside its usual realm of application. The loads should be applied farfrom the section of interest according to Saint Venant’s hypothesis, and the structure shouldbe highly elongated, preferably with a width-to-length ratio over 5, which is not the case in ourevaluation. However, this quick calculation was found to be the most straightforward way tocheck our initial design. Without doing these calculations and starting from a FEA analysiswithout any experimental data to compare with could have given highly unreliable results fromthe start.

According to the beam theory, the highest value of normal stress will be located at thefurthest points away from the centerline. In our case that would suggest these normal stresseslie along the outer edges away from the centerline of the bonded base. The shear also has to beconstant along the main axis, therefore we can use the Von Mises criterion, Equation 4.10 tocombine the effects of normal and shear stresses and compare with the maximum shear strengthof the material.

√

σ21− σ1σ2 + σ2

2< σmaterial (4.10)

In the case of our preliminary structure the calculated Von Mises maximum stress is 2.08 MPaconsidering a 197 mm offset from the secondary bulkhead and the applied 30 kN, comparedto the shear strength of Rohacell 110 IG as 2.4 MPa. This gives us 15% contingency, whichunfortunately is not the biggest buffer but will have to suffice as this is the highest grade ofRohacell in this series.

We can now use the hand calculations as a rough basis for our FEA. To carry out the FEA

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on the side loading of the Rohacell crush structure a simplified model was constructed thatincluded the required 100mm x 300mm side push off pad.

Figure 4.5: Simplififed Rohacell Nose Cone Structure for FEA Optimisation

The side push off pad was included in the model on the assumption that as the pad was alsoto be manufactured from Rohacell, during the side loading the push off pad and the nose conewould effectively become one structure. This addition of the pad to the model file ensured thataccurate loading orientation would be achieved and that a simplified mesh could be generatedwithout the need for sectioning or a complex assembly file.

Another assumption for the generation of the FEA model was that the crush structure wasto be manufactured from one piece of Rohacell. This was not to be the case in the actualmanufacture of the component but as the shear strength of the adhesive used far exceeded theshear strength of the Rohacell this was not considered for the analysis.

The final assumption was that an infinitely strong bond was achieved between the crushstructure and the secondary bulkhead. As the tensile and shear properties of the adhesive usedfar exceeded the material properties of the Rohacell this assumption enabled the crush structureto be constrained on the back face and meant that the secondary bulkhead did not need to beincluded in the analysis.

For all FE calculations carried out on the Rohacell crush structure the following propertieswere used, as taken from Rohacell.com; Young’s Modulus, E = 1.6 × 108 and Poisson’s Ratio,ν = 0.38[11]. Initially, there were values supplied for Young’s Modulus and Shear Modulus, butin using these to determine Poisson’s ratio it generated an unrealistic value of 0.6. It was foundthat by using the supplied data for Young’s Modulus and Poisson’s ratio and allowing I-Deasto solve for Shear Modulus, the analysis generated better results.

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The loading and constraint boundary conditions that were used for all analysis was a dis-tributed force of 30kN acting on the face of the push off pad and the rear face fully constrainedin translation and rotation. The constraint set imposed can be seen in Figure 4.6

Figure 4.6: Loading and Constraint Boundary Conditions for Rohacell Structure

It was suggested during the design of the secondary bulkhead that a lip could be positionedaround the perimeter of the top plate to provide additional surface area to bond to the Rohacellfoam. This was considered to be a good idea in terms of strength of tensile / compressiveattachment but the effect in side loading was not known so it was decided that a FE analysisshould be carried out on the effect of the lip size.

To represent the lips to be analysed, the CAD model was modified to provide a parallelsection at the base of the crush structure that was the height of the proposed fence. Theseareas could then also be constrained in all translation and rotation to represent the bonding ofthe foam to a steel side fence.

The first FE model that was generated with the additional 20mm bonding edge around theperimeter is seen in the Figure 4.7.

It was determined from experimental testing that failure occurred at the join line betweenthe steel lip and the Rohacell foam. We now had some experimental data to use as a referenceto evaluate the validity of the FEA that was generated. We know from the manufacturer’sdatasheets that the maximum shear stress of the material is 2.4 MPa. By inputting the exper-imentally obtained force, which caused the structure to fail in two different test cases, into theFEA simulation we found that there was an offset in the results of the FEA of approximately2.4 MPa. Continued use of the FEA results would have to take this offset into account.

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Figure 4.7: Rohacell Structure with a 20 mm lip Loaded at 30 kN

With this correction in mind we examined the FEA results seen in Figure 4.7, the peakstress for the 20mm fence was 8.36MPa, now a corrected value of 5.96MPa, would not meet theside push off requirements.

The analysis was also re-run with a larger side lip, it was originally suggested that increasingthe size of the side lip would increase the bonded area, reduce the moment experienced at thetop of the bond region and translate more of the load into shear giving an overall reduction instress at the point the steel fence joins the foam.

With the side lip size increased to 90mm it was found that peak stress at the foam/steeljoint line increased rather than decreased as had been hypothesised. The peak stress value fromthe analysis was found to be 9.19MPa (Corrected: 6.79 MPa), as can be seen in Figure 4.8, anincrease from the 20mm fence model of 0.83MPa. This was an unexpected result as it had beenreasoned that the stress at the join line would decrease with lip height.

To confirm that the effect of increasing fence height resulted in increased peak stress theanalysis was re-run with a fence height of 115mm, Figure 4.9.

After the analysis with a fence height of 115mm was complete it was identified that thepeak stress at the join line had again risen and was now 9.34MPa (Corrected: 6.94 MPa).This confirmed that the original hypothesis was incorrect and that minimum stress during sideloading would occur without side lips. To confirm that this theory was correct the model wasfinally run with only the back face constrained to represent the model without bonded sidefences, Figure 4.10.

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Figure 4.8: Rohacell Structure with a 90 mm lip Loaded at 30 kN

Figure 4.9: Rohacell Structure with a 115 mm lip Loaded at 30 kN

This final analysis confirmed two positive results. Firstly that the lowest peak stress duringthe 30kN side push off loading would occur on the design without side fences and secondly thatthe magnitude of stress at the foam/steel join line could be estimated as 5.5MPa (Corrected:3.1 MPa), just above the limit of the Rohacell material.

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Figure 4.10: Rohacell Structure without side lips Loaded at 30 kN

This suggested that the foam crush structure design could potentially pass the side push offtest if it was bonded on the back face only without the use of side lips.

4.4.3 Adhesives

The maximum thickness for the Rohacell material is limited to 75 mm, but because of our largemonolithic stucture we would require some method of keeping the pieces together so some forof adhesive was also researched. In addition, to simply keeping the individual layers togetherwe also needed a relatively simple method of attaching the final block to our bulkhead withoutsignificantly adding stress concentrations or incorporating incompressible components to thefoam and so it was decided that an adhesive would also be used for this attachment surface.

The requirements for the adhesive were ultimately that it must have excellent shear strengthwhile being easy to apply and cure at room temperature.

Several two part epoxies were investigated for use, namely those in the Araldite 2000 seriesand Redux 600 series made by Huntsman Advanced Materials. These all have fairly good shearstrengths within the mid 20 MPa range at room temperature. However, there is one otheradhesive that surpassed these in terms of shear strength, Araldite 420A/B, also produced byHuntsman. This adhesive has a shear strength up to 35 MPa at room temperature.[1]

Araldite 420 requires a 0.1 mm adhesive layer to achieve its optimum shear strength. A fullcure at room temperature is obtained in 7 days, but can be accelerated by heating at 50◦C for4 hours.

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During production of our full size test pieces, we were unable to acquire a sufficient amountof Araldite 420, so as a temporary substitute we used Scotch-Weld 7260 B/A from 3M[2]. Thisadhesive was the closest match to the Araldite that was available to us, with shear strengthalso in the mid-30 MPa. There was one surface which was bonded with this adhesive, and theremaining model were still constructed with Araldite as there was an expedited shipment of therequired stock.

4.5 Secondary Bulkhead

The initial design requirement made little to no mention about the attachment of the crashstructure to the main chassis of the vehicle, and from Ford’s point of view as long as weattached our structure to a flat plate of 300mm x 300mm, that would be sufficient. However,we wanted to design something which could be attached to the vehicles if necessary so thatrequired additional considerations due to the space occupied by the steering rack and mastercylinders as these sit in front of the original bulkhead. Without these pieces attached to thefront we would have an excellent surface to work with, but realistically we had to find a way towork around them.

From the onset we decided that the best way to solve this problem is to build out a secondbulkhead in front of the steering rack and the master cylinders both to protect these expensivecomponents as well as provide us with a flat surface to push against and then transmit residualforces to the main chassis.

4.5.1 Analysis of Secondary Bulkhead

It was determined that the secondary bulkhead may have to withstand instantaneous peakloads of 167kN during a worst case impact and so it was necessary to manufacture a structurethat would not fail during this loading. This peak load was determined from the assumedcompressive force of 3 MPa over an area of 196 mm x 280 mm, the updated base area for oursecondary bulkhead. The belief was that the Rohacell would be transmitting 3 MPa to theback plate as it was being compressed, and this would be the forces the structure would haveto withstand.

As an initial design had been previously generated that met the geometric constraints ofavoiding the three master cylinders and providing a flat base for the crush structure to bemounted on, it was then necessary to optimise this design to withstand the required input loadsusing finite element methods.

It was identified that there were three major areas of optimisation for the secondary bulkheadto enable the structure to withstand the required input loads. These were; the type of materialchosen for the bulkhead, the wall thickness of the material used and the addition of ribs andbraces to the structure to increase its strength.

It was decided early in the design stage of the secondary bulkhead that the componentshould be constructed from steel rather than aluminium to reduce the time and skill requiredfor manufacture and to reduce material costs, therefore it was decided that the structure shouldbe made from a medium carbon steel with an approximate yield strength of 400MPa.

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Figure 4.11: Initial Design of Secondary Bulkhead before Optimisation

For all FE calculations carried out on the secondary bulkhead the following generic steelproperties were used; Young’s Modulus, E = 2.068 × 108; Poisson’s Ratio, ν = 0.29; and ShearModulus, G = 8.0155 × 107.

To identify what optimisation of the structure was required for it to withstand the calculatedworst case input loading of 167kN an FE Analysis was carried out on the initial design with aproposed box section thickness of 1.5mm and a 3mm top plate.

Figure 4.12: Analysis of Initial Design: 1.5 mm wall thickness, 167kN distributed on topplate,constrained at base of feet, and 5mm solid tetrahedral elements

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As can be seen in Figure 4.12, the initial design did not meet the requirements for thestructure. At the side of the plot a colour contoured stress scale can be seen that rangesbetween 0-400MPa. The contour range in this case has been set to the elastic range of thematerial proposed for the construction of the component. It is particularly useful to set therange in this way as it clearly identifies areas in black that have exceeded the upper limit andhave effectively yielded and therefore require some improvement. As can be seen in the previousfigure, black areas to represent material yield were found in all areas of the model frame and soa wall thickness increase was proposed to 2mm.

It is also possible to display the FE plot so that it displays the calculated deformation of thecomponent, as can also be seen in Figure 4.12. This feature allows direct visual identificationof the areas of the component that may require additional stiffness in the form of braces orribs. It can clearly be seen that the 3mm thick top plate used to mount the crush structure hasdeformed dramatically during loading. Since the plate was already 3mm it was decided that anadditional vertical cross brace at the centre of the span was a better option to stiffen the platerather than continuing to increase its thickness.

It was also observed that as the structure was effectively symmetric along two planes it waspossible to increase the analysis speed by imposing symmetry boundary constraints and henceonly analyse a quarter of the model, as seen in Figure 4.13. Symmetry boundary constraintsforce the model to behave as if the whole model was still being loaded but as the effective modelsize has been reduced, the number of elements required and the relative calculation time canbe reduced. It is also possible to increase the analysis accuracy by increasing the number ofelements and still retain a faster calculation time.

Figure 4.13: 1/4 Model with Symmetry Boundary Conditions

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Once the symmetric quarter model had been modelled, the box section frame wall thicknesswas increased to 2mm and the central top plate brace was added. It was possible to run anotherFE analysis to identify the effective of the proposed changes.

Figure 4.14: Analysis on Revision 1 Design of 1/4 Model: 2 mm wall thickness, 167kN distributedon top plate, constrained at base of feet, 5mm solid tetrahedral elements

As can be seen in Figure 4.14 (Stress Contour Range 0-400MPa), the proposed modificationsto the design were not sufficient to prevent material yielding across much of the component. Toreduce the deflection of the frame members and to increase the stiffness of the joint between theframe members and the upright, triangulated braces were proposed to be manufactured fromthe same box section material as the frame.

It was also observed that large deflections were still occurring in the top plate. The verticalrib that had been added did have an effect on the deflection but the span between the innersurface of the frame and the rib was simply too large to have fixed the problem completely. Toattempt to reduce the deflection further, an additional vertical rib was proposed so that a ribwould be positioned across the frame at one third and two thirds of the span.

It was suggested that the results may contain inaccuracies due to the coarse mesh used forthe analysis and more realistic results could be achieved with a finer mesh.

The proposed changes of triangulated corner brackets and additional / repositioned top platebraces were modelled into the design in 3D CAD and then the analysis re-run with a mesh sizeof 1.5mm to identify the effects of the changes made;

From the analysis of the revision 2 bulkhead in Figure 4.15, the proposed modificationsmade a dramatic effect to the stresses acting on the component but they were not sufficient tototally prevent material yield in all areas.

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Figure 4.15: Analysis on Revision 2 Design of 1/4 Model: 2 mm wall thickness, 167kN distributedon top plate, constrained at base of feet, 1.5mm solid tetrahedral elements

It could be seen that the triangular braces at the joint between the frame members and theupright had reduced the stresses in one of the members so that it was within the elastic rangeof the material and had significantly reduced the stresses in the other. It was also observed thatthe deflection of the top plate had reduced with the addition of the second brace so that themajority of the plate was no longer yielding.

It was suggested that the high stresses observed at the point where the lower edge of thetwo triangular plates met could be due to either a stress concentration in this area or becauseof a calculation error caused by the tight geometry at the point. It was suggested that localisedmesh refinement would increase the accuracy of the results obtained in this region and thesurrounding area and enable the cause of the high stresses to be identified.

To further reduce the stresses acting on the frame and to attempt to ensure that all areaswere within the material’s elastic limit during worst case loading the wall thickness of the framebox section was increased to 2.5mm for revision 3 and the analysis re-run with all additionalstrengthening retained.

It can be seen in Figure 4.17 that even with the increase in frame wall thickness to 2.5mmit was not possible to ensure that all areas of the secondary bulkhead structure were within thematerial’s elastic limit during worst case loading. The increase in wall thickness had reducedthe stress in both the frame member and the upright considerably and so it was thought thatthe required result of all components within elastic range could be achieved by further increasein wall thickness.

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Figure 4.16: Localised Mesh Refinement at Edge of Triangular Braces

Figure 4.17: Analysis on Revision 3 Design of 1/4 Model: 2.5 mm wall thickness, 167kN dis-tributed on top plate, constrained at base of feet, 1.5mm solid tetrahedral elements

However a consideration was made at this point that the component was becoming increas-ingly heavy and, as it was being designed for a light weight Formula Ford car, it could be that

27

the initial design requirement was unachievable without a considerably thick and heavy steelstructure that would be unsuitable for the intended purpose. It was decided that as a largeamount of the structure was within the material’s elastic limit of 400MPa and the majority ofthe remaining structure was within the materials tensile limit of 600MPa the component wouldbe manufactured to this specification and hence the optimisation was complete.

4.6 Final Design

We have generated two designs which will be briefly described in terms of function and cost.The prototype structure are the ones which we tested, though there are some small differences,and the final design is the one which we are proposing with some potential improvements afterevaluating the results of our tests.

4.6.1 Prototype Secondary Bulkhead

Figure 4.18: Prototype Structure

As seen in Figure 4.18, the four box section steel legs of the secondary bulkhead act againstthe face of the primary chassis bulkhead tubes and are attached to the primary bulkhead byfour bolts fitted through holes in the tabs on the ends of the secondary bulkhead legs.

The upper leg mountings consist of two tabs each that go either side of the primary chassistubes while the lower leg mountings consist of one tab each that rest against the outside of theprimary chassis tubes.

The upper bolts go through the upper tabs and chassis tubes (which have steel inserts weldedin to house the bolt shank) and require a nyloc nut to fix them in place. The lower bolts gothrough the single tabs and screw into a threaded insert welded within the primary bulkheadtube.

The four legs are welded to the box sections that make up the square front portion of thesecondary bulkhead with two triangulated reinforcement sections welded in on either side of

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each leg to add strength. The legs come in at a small angle towards the tip of the nose so as toallow the fitting of the bodywork (i.e. they protrude inwards).

The front portion has a flat steel plate welded to it to act as a reaction and bonding surfacefor the Rohacell foam. The rear of this face plate is reinforced by two steel plate ribs weldedon. There is more plate welded around the edges of the front section so as to give a lip all theway round providing a box for the cone to be located in and also to give extra area for bonding.

4.6.2 Final Structure

Figure 4.19: Final Structure

The structure in Figure 4.19 is very similar to the prototype version apart from the twoupper legs, which are shorter and act against the steering rack brackets as opposed to theprimary bulkhead itself. The upper legs only have one attachment tab through which a boltgoes and screws into a threaded hole in each steering rack bracket.

This is done so that Spirit did not have to make significant changes to the design and locationof their current steering rack, but this does require small modifications to the current mountingbrackets.

Some key areas for improvement would be the following:

• a composite skin to improve the performance of the energy absorbing structure, we suggesta 2 to 3 ply of woven fiberglass and polyester resin to keep production and material costsdown

• further optimise the secondary bulkhead the further strengthen the support and reducethe overall weight of the structure

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4.6.3 Manufacturing Costs

Assumptions for the Manufacturing Process

In order to cost the manufacture of the crash box, following assumptions have been made:

• The design is such that it can be manufactured at Spirit’s own facilities.

• The crash box will only require minor modifications to fit other manufacturers’ chassis.

• Standard costs for parts and materials have been used from Spirit’s suppliers and fromother external suppliers.

• The costs of any finishing processes have not been included.

• The cost of attaching the crash box to the car is not included but an estimate of time andcost of assembling is included.

• Labour costs are based on Spirit’s hourly rate of £35.

• Machining costs are £6/hour, based on an average of universal machines.

• A 20% set-up allowance is added to every job. This covers the additional time needed toset-up the machine, to clean it and for the additional adjustments to be made.

• Welding costs, drilling costs and sawing costs are based on the official SAE estimates.(welding=£0.14/cm; sawing=5min/piece; drilling=3min/hole)

Schedule Of Materials

The materials used to construct Team Spirit’s frontal crash structures can be seen below inTables 4.2 and 4.3, also listed in Appendix C:

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Table 4.2: Bill of Materials for Prototype Structure

Table 4.3: Bill of Materials for Final Structure

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Full Manufacturing Costs

Tables 4.4 and 4.5 show the total cost to produce a single product, either of the prototype orfinal structures. These tables are also listed in Appendix C.

Table 4.4: Total Cost to Produce a Prototype Structure

The cost of both designs are summarised in Table 4.6:

Mass Production

The breakdown for the production of 20 or 50 crash structures of the final design is listedin Table 4.7

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Table 4.5: Total Cost to Produce a Final Structure

Prototype Design Final Production Design

Total Labour £140.35 £146.65Total Machine £24.06 £25.14Total BOM £163.35 £163.03

TOTAL £327.76 £334.83

Table 4.6: Summarised Total Costs

Quantity

1 20 50

Total Labour £140.35 £2,925.00 £7,312.50Total Machine £24.06 £502.80 £1,257.00Total BOM £163.35 £3,260.80 £8,152.00

TOTAL £327.76 £6,688.60 £16,721.50

Table 4.7: Volume Costs

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5 Testing

5.1 Original Crash Structure

It was observed by the group that an easy solution to the design problem would be to either usethe existing design, if it met the performance regulations set, or to carry out some modificationsto the current design in order to increase its impact performance. In order to obtain some baselevel crush performance data and also to identify if this was a possibility; a static crush testwas performed on a current production Spirit crush structure.

5.1.1 Modifications Carried Out For Testing

To enable the current production Spirit crush structure to be tested a number of modificationhad to be carried out.

Figure 5.1: Spirit Crush Structure Prepared for Testing

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The first consideration during test preparation was the representation of the chassis mountsto the crush structure. It was observed that three options were available; to mount the crushstructure onto a car bulkhead, to connect the upper and lower mounts with a solid link or totest the crush structure as a stand alone unit and not represent the mounts.

As the purpose of the test was to identify the performance of the crush structure and notits relation to the chassis mounts it was decided that the unit should not be mounted to abulkhead. However, it was considered necessary for the mounts to be connected to stop theunit separating unrealistically during testing so solid link representation was used. This wascreated by using two lengths of M6 studding threaded through the mounts and locked at eachside by nuts secured either side of the honeycomb plate, as seen in figure 1 The use of M6studding produced a solid link that was also compliant during high compressive loading.

Another test setup consideration was the modification of the crush structure to enable it tobe stable on the base plate during testing. A design feature of the Sprit crush structure is arecessed section at the top of the unit to enable the integration of the crush structure aroundthe steering rack. The recessed area was squared off and then the remaining area was filledby a 10mm steel plate and 40mm of dense wood. The combination of a steel plate and densewood was used to minimise compliance during compressive testing, however it was observedthat errors may be still be present in the results due to compression of the wood and also as aresult of stress concentrations at the corners as a result of the squaring off process.

5.1.2 Static Crush Test

For the test the crush structure was first placed onto the base plate of the compressive testmachine which was then raised until the front face of the crush structure was in contact withthe top plate. The static crush test programme was then started which raised the table bya fixed displacement input of 30mm/min while monitoring the force required to produce thisdisplacement

During the test sequence a number of observations were made about the design of the currentSpirit crush structure and its ability to absorb the crush loading.

The structure is made up of a net of 5 aluminium honeycomb sheets that are held togetherby steel angle plates riveted to the external skin of the aluminium honeycomb. During theinitial stages of loading the rivets that held the bottom honeycomb plate to the structure, seenon the right of figure 2 were drawn through the side aluminium skins detaching it from themain body. This resulted in bending of the lower front angle plate rather than compressionof the bottom honeycomb plate as it was not sufficiently restrained. The energy absorption ofthe crush structure was therefore only based on the three remaining honeycomb plates. Thecrush characteristic of the remaining structure was found to be reasonably effective. As can beobserved in figure 3 the top and side honeycomb plates and the side angle brackets displayedhighly uniform concertina buckling. This uniform crushing occurred up to the point of thesteering rack recessed area where the structure became solid and the test was stopped.

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Figure 5.2: Spirit Crush Structure Before Static Crush Test

Figure 5.3: Spirit Crush Structure After Static Crush Test

5.1.3 Results of Testing Original Structure

To determine if the performance of the Spirit crush structure was acceptable under the newregulations analysis of the results was carried out. As previously discussed in the Hand Cal-culations section of this report, section 4.2.1 for a crush structure to meet the criteria it must

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have an average crush strength of 150kN and absorb 43kJ of energy over 300mm of deflection.

As shown in figures 5.4 below, it was found that the current Spirit design does not meet thenew regulations. In terms of crush strength the Spirit design displayed an average of 60.7kNduring static crush which is only 40% of the 150kN dynamic crush strength required to meetthe regulation. In terms of energy absorption the unit could only absorb 12kJ up to 200mmdeflection before the structure contacted the 10mm steel support plate and became solid. Thishighlights two concerns with the current design; firstly, based on an extrapolated linear curve,the unit can only absorb approximately 18kJ of energy over 300mm deflection which is only 42%of the required 43kJ energy absorption and secondly the unit become solid before the required300mm deflection to ensure a deceleration value of less than 25g.

Figure 5.4: Original Spirit Crush Structure Static Load Test

5.1.4 Conclusions Of Testing Original Structure

The testing of the Spirit crush box highlighted several important factors that will enable thedesign process of the new crush structure to progress. Firstly it has confirmed that the currentdesign of riveted aluminium honeycomb plates will not meet the regulations and that if thenew design is to be based on a similar concept development must be carried out. The areas fordevelopment could be the method in which the plates are joined, the selection of a higher energyabsorbing honeycomb plate or the filling of the internal volume with an absorbing material. Ithas also shown that to meet the <25g deceleration criteria the steering rack must be moved orthe length of the crush structure must be increased.

It has also provided base level data in which to compare any subsequent prototype testingshould an alternative crush absorption method be used.

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5.2 Final Design

The tests for each type are listed chronologically, but the individual tests may not have beencompleted in the order below. In total there were three static tests, two full size and one scaleddown model. Three push off tests, all on full size models, and lastly a single dynamic test on afull size structure.

5.2.1 Static Crush Test

This preliminary test will provide a baseline indication of the integrity of the design solutionand its ability to meet the requirements of the push off test and impact test by apply theequivalent amount of energy from the dynamic test. However, because this test is performed ina quasi-static equilibrium we will be less prone to causing damage to the equipment.

The test equipment has a limit of 200 mm of travel during testing and as our structure isover double this length, the testing had to be done in a number stages where the structure isreleased and the machine is reset to continue crushing. When the structure was released thefoam has a slight rebound, so when the data was recompiled each stage was stitched togetherat matching load points.

First Static Crush Test

This first structure was based on our first prototype with a lip of 20 mm for the secondary bulk-head. This structure was then attached to our adapter plate which simulated Spirit’s chassis.This structure had a total volume of 0.014 m3 which gives a theoretical energy absorption of43 kJ and a mass of 1.58 kg. The Rohacell layers were bonded longitudinally to save on labourcosts as there are only two surface to bond but unfortunately this may have contributed tosome premature cracking and separation of material from the structure, as highlighted in redof Figure 5.5.

Though there was some loss of material, the majority still managed to compress and absorba reasonable amount of energy, a total of 29.56 kJ with the average load of 73.97 kN. Thefirst thing to notice about this test, Figure 5.6, is that it is a significant improvement over theoriginal structure that we tested, Figure 5.4.

Second Static Crush Test

The second structure that was tested had the larger set of side lips for the secondary bulkhead,115 mm in height, but the bonding direction was still the same as the first structure. The totalvolume had increased slightly to 0.02 m3 to maintain the vertical profile along the sides of thebulkhead lips. This additional material also increased the mass of the foam block to 2.21 kg.As such the performance was similar, Figure 5.7, absorbing a total of 32.87 kJ of energy withan average load of 88.28 kN.

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Figure 5.5: Cracking of Structure

Figure 5.6: Static Crush of First Full Size

Third Static Crush Test

The final static test was performed on a small scaled down sample as a verification of theperformance if the Rohacell layers were bonded in a vertical orientation. Each dimension was

39

Figure 5.7: Static Crush of Second Full Size Structure

scaled down 70% resulting in a volume of approximately one third that of the full size model.This smaller version absorbed 15.48 kJ at an average load 53.62 kN as seen in Figure 5.9 andextrapolating the full size version as three times the volume we estimate that it would havebeen able to absorb approximately 45 kJ. This is a 50% increase over what we had originallytested with the bonding in the other direction. During the testing the material was much lessprone to separating off the sides as seen in the series Figure 5.8.

In our case, the structure obviously exhibits a much more complex behaviour. Two mainfeatures of our design are supposed to be the cause: - adjunction of bond joints - tapered andcurved shape.

The difference between the theoretical and practical energy absorption values can firstlybeen explained by the formation of numerous cracks across the structure. Those seem to havetwo causes: - stress concentration around the bond joint - shear stress concentration due to thelocal curvature.

40

(a) (b) (c)

Figure 5.8: Crushing of Scaled Down Model

Figure 5.9: Static Crush of 70% Scale Structure

41

5.2.2 Side Push Off Test

As defined from our original product brief:

To test the attachments of the frontal impact absorbing structure to the spaceframe chassis, a static side load shall be placed on a vertical plane passing 400mmin front of the front wheel axis.

A constant horizontal load of 30kN must be applied to one side of the crashstructure using a pad, 100mm long and 300mm high, with a maximum radius on alledges of 3mm. The centre of area of the pad must pass through the plane mentionedabove and the mid point of the height of the structure at that section.

After 30 seconds of application, there must be no failure of the structure, or ofany attachment between the structure and the space frame chassis. During the testthe space frame chassis must be resting on a flat plate and secured to it solidly butnot in a way that could increase the strength of the attachments being tested.

First Side Push Off Test

For the first side push off test, the design tested was the bare Rohacell crush structure bondedto the secondary bulkhead with an additional 20mm lip to increase the bonded area betweenthe steel structure and the foam.

A side push off pad that complied with the 100mm x 300mm requirement was producedfrom the excess material that was removed during the nose manufacture to ensure that thestructure was loaded perpendicularly to the crush nose centre line.

A load cell was placed between the side loading jack and the push off pad to enable measure-ment of the load applied during the test and DTI’s were positioned opposite the load pad and atthe furthest forward point of the secondary bulkhead to measure the respective displacement.The test setup for this first push off can be seen in Figure 5.10.

Results

The side push off test was to be carried out in two stages. Stage 1 being the progressiveincrease in load applied to the structure from 0 to 30kN and stage 2 being the 30sec timedperiod that the load must be maintained. During the stage 1 progressive loading the Rohacellcrush structure failed at a load of 20kN at the point of the join between the foam and the steelfence.

Discussion & Conclusions

It was determined from hand calculations carried out before testing that the Rohacell ma-terial would be stressed below its failure range at the loading required by the side push off test.However, as little test data was available for the materials properties in this situation it wasnecessary to carry out the test to identify the materials characteristics.

From analysis of the failure surfaces of the Rohacell crush structure and the secondarybulkhead, Figure 5.12, it was observed that the failure occurred initially at a point just aboveone of the 20mm side lips and then propagated at a rough angle of 45◦ to the adhesive surfaceon the top plate of the secondary bulkhead, where the material continued to separate just off

42

Figure 5.10: First Attempt at Push Off Test

Figure 5.11: Moments Before Structural Failure at a Load of 16.2kN

the surface of the adhesive. The good news about this test was that alleviated any worriesabout the adhesive disbonding from the metal surface of the secondary bulkhead as all of theadhesive remained intact. It was decided that an alternative design must be manufactured thatreduced the stress experienced at the foam / steel join line.

43

(a) Bulkhead (b) Foam Block

Figure 5.12: Remains of First Push Off Test

Second Side Push Off Test

For the second side push off test, the design tested had the Rohacell crush structure bonded tothe secondary bulkhead with a larger 115mm lip to further increase the bonded area between thesteel structure and the foam. In addition to the greater area, it was proposed that an increasedside lip height would reduce the moment at the point and thus reduce the tensile stress on thematerial but increasing the shear loading.

As the cross section at the point of loading was the same as in the previous test the sameside push off pad was used as test 1.

Again the load cell was installed between the side loading jack and the push off pad toenable measurement of the load applied during the test and DTI’s were positioned opposite tothe load pad to measure the displacement.

Results

It was expected that the increase in lip height would reduce the tensile stress at the joinline and hence increase the maximum achievable side load force, however this was not the case.

During the progressive loading, the Rohacell crush structure failed at a lower load of 16kNalso at the point of the join between the foam and the steel lip, but now further up the structure.

Discussion & Conclusions

The second side push off design was generated in haste as a product of failing the first sidepush off test. The modifications made to the original design were determined by discussion andbasic calculations, not reasoned analysis as they should have been. This resulted in a designthat was worse than the original.

From analysis of the failure surfaces, Figure 5.14, it was again observed that the failureoccurred at the point just above the top of the one lip. The failure then propagated across thewidth of the structure as the Rohacell material progressively failed.

44

Figure 5.13: Second Attempt at Push Off Test

It was decided that a further FE analysis should be carried out on the side push off loadcase as described in Section 4.4.2 to attempt to fully understand the cause of the early failureduring the second test.

Third Side Push Off Test

It was determined, from the FE analysis carried out on the side push off, that the lowest stressoccurred in the model without the side lips, however the FE results achieved were still too closeto the failure range of the Rohacell material and so it was considered too risky to carry outanother test that had a possibility of failure.

Instead it was decided that the side push off test should be carried out by positioning theside push off pad on the 115mm side lip at a point 100mm closer to the wheel centerline ratherthen directly on to the Rohacell nose as seen in Figure 5.15. It was determined by calculationthat the steel secondary bulkhead would be able to easily withstand the loading required andwould enable the design to pass the side push off test stage. This test procedure was validatedby the fact that the regulations state that the load ’must be applied to one side of the nose cone(containing the nose crash box structure)’.

Results

As had previously been calculated, the structure was able to withstand the 30kN whenthe side push off loading was applied to the fences of the secondary bulkhead and was able to

45

Figure 5.14: Top View of Crack in the Foam Structure During Second Push Off Test

Figure 5.15: Placement of Pad in Third Push Off Test

46

maintain the load for the required 30secs. Based on the previously discussed assumption thiswas considered a test pass. However, it has to be noted that the lateral attachment bracketsof the second bulkhead bent and this resulted in a 2 mm permanent lateral translation of thecrash structure as seen in Figure 5.16. It has to be said that this should not interfere with thedynamic crash behaviour of the whole structure as during the crash, the majority of the load istransmitted longitudinally to the front bulkhead of the chassis. These brackets were made outof 3mm thick mild steel. They could be made thicker or out higher grade steel, but we decidedto keep this same design for the final version for both weight and cost concerns considering thatthis would neither affect the integrity of the structure nor the crash worthiness.

Figure 5.16: Translation of Side Tabs in Push Off

Discussion & Conclusions

As previously discussed the method of passing the side push off test by pushing on the steelside fences was not the original design intention but can still be considered a validation of thedesign.

The side loading of the crush structure was still carried out on a position that was predomi-nantly made up of energy absorbing material and the assumed distance from the car front axlecentre line was made on the basis that this value could be changed for the ’08 car if required. Ifthe assumed value was not considered valid it could also be possible to further extend the sidefences and include them as part of the crush structure to enable the test to be carried out ata point 400mm from the existing car centre line, rather than the 300mm for this final push offtest.

47

5.2.3 Front Impact Test

As defined from our original design brief:

For the purposes of this test, the total weight of the trolley and test structureshall be 595kg and the velocity of impact 12m

sThe space frame chassis and nose

assembly shall be subjected to an impact test against a solid vertical barrier placedat right angles to the centre line of the car. The resistance of the test structuremust be such that during the impact the average deceleration of the trolley does notexceed 25g. The chassis must not suffer damage as a result of the above test.

However, for the final test setup we used a sled with a mass of 660 kg and ran at a slowerspeed to obtain an equivalent energy. An image of the setup can be see below:

Figure 5.17: Sled with Final Test Model Mounted

This last structure which we tested is built similarly to the first structure used in the statictests, except that the bond direction is vertical as was tested in the third static test, Section5.2.1. The total volume for this structure is 0.0192 m3 and a mass of 2.11 kg and therefore itsestimated energy absorption is 53kJ, although we have to keep in mind that the static test onthe scaled structure estimated an energy absorption of 45kJ.

The test speed was 11.41m/s and the data shows that a mean g over the course of the impactwas 16.25g. The design requirement was to have an overall average g less than 25g, which isclearly obtained by a margin of 8.75g.

The mean g for the first 150mm of crush was 7.35, peaking at 11.61g. Once the crush lengthreached the region of 190mm, the acceleration had peaked at 13.12g in a time of between 17 and18ms. The acceleration is then seen to drop off over the next 15ms to 6.72g until a crush length

48

Figure 5.18: Resulting Data From Dynamic Test

of 330mm is reached and the sled has been slowed to 8.41m/s. This drop off in acceleration isdue to a crack propagating on the top and bottom surfaces seen in Figure 5.19, leading to lessof a deceleration because the material is giving way without compressing meaning there is notas much material available to resist the impact.

During the next 37ms (total time of 70ms) the acceleration rises to a test highest peak of41.33g and the sled has been slowed to 0.7m/s with a crush distance totalling 536mm. Theincrease in acceleration up to 41.33g can be accounted for by the breaking up of the nose intolarge pieces resulting in the metal secondary bulkhead taking the load and having to deformgiving a more severe deceleration, see Figure 5.20 Zero velocity is reached after a total crushtime of 71.45ms and a total crush length of 537mm.

The concluding points to the dynamic test are that there was a very good initial crush forthe first 190mm where the material broke up into small bits. However when the nose cone thenstarted to break up in to large pieces the energy was not well absorbed and the sled did notslow as quickly or controlled as we had hoped. This could be overcome by making the entiretyof the crush work as it did within the first 190mm with all material being destroyed or crushedinto small pieces. This could be achieved by enclosing the foam structure within an outer skinmade of composites such as GRP, carbon fibre, or possibly even aluminium.

49

Figure 5.19: Early Failure of the Material at 17 ms After Impact

Figure 5.20: Additional Loss of Material at the Base at 46 ms After Impact

50

6 Conclusion

We have demonstrated the crash worthiness of a very innovative material. The use of Degussa’sRohacell high density polymer foams is definitely recommended for motorsport crash applica-tions and especially in the low cost environment of Formula Ford. The Rohacell foam exhibitsthe following upsides:

• homogenous structure

• isotropic properties and therefore good off-axis loading tolerance

• high Specific Energy Absorption

• very easy manufacturing well adapted for small manufacturers

After numerous physical tests and calculation, we have specified a design for Spirit RacingCars’ Formula Ford chassis integrating such an absorbing structure. This design increasessignificantly the safety standards of the car and passes all the test requirements specified at thebeginning of the project. The absorbing structures structure itself only weighs 2.1 kg withoutskinning and 3.3 kg with a composite skin to improve the performance as well as provide day-to-day protection. This normally comes with a removable frontal chassis extension which weighs3.1kg in its latest revision. Compared to the original aluminium sandwich panel design, theabsorbing core material almost absorbs four times as much energy for a similar weight andthe manufacturing cost of the absorbing material alone is even lower. The version withoutcomposite skin costs £334 including the chassis extension which is 15% under the initial costtarget.

The definite advantages of our solution are:

• very good energy absorption figures

• very reasonable weight

• safety for other competitors (especially in case of side impact)

• low manufacturing cost

• manufacturing simplicity

51

Bibliography

[1] Huntsman advanced materials - araldite 420 a/b.

[2] www.3m.com/bonding.

[3] www.aluminium.matter.org.

[4] www.azom.com.

[5] www.chm.bris.ac.uk/webprojects2002/mjames/chemistry.html.

[6] www.degussa.com.

[7] www.fia.com.

[8] www.hexcel.com.

[9] www.msauk.org.

[10] www.plascore.com.

[11] www.rohacell.com.

[12] www.ukformulaford.co.uk.

[13] Rickard Juntikka. Rohacell 31 ig - crash behaviour. Technical report, KTH Aeronauticaland Vehicle Engineering.

[14] K. Tucker, N.; Lindsey. An introduction to automotive composites. Technical report, RapraTechnology Shawbury, 2002.

[15] Marino Xanthos. Functional fillers for plastics, 2005.

52

A Secondary Materials

Some materials relevant to the initial crash box design ideas have been looked at for initialevaluation. They can be broken down into two main sections namely skin materials and corematerials.

A.1 Skin Materials

Aluminium

Pure aluminium is soft and malleable and must be alloyed with other elements such aszinc, copper, magnesium, silicon, lithium and manganese for higher strength applications suchas automotive structures. Aluminium alloys have excellent corrosion resistance and strength-to-weight ratios (see Table A.1) due to it having a density of only 2.7 g

cm3 , one third that ofsteel.

Properties: They are very versatile alloy materials primarily because of the ability to formthem into complex structural shapes, without the need of addition of additives.

Property S-Glass Carbon Steel Aluminium

Tensile strength (MPa) 4600 3800-6530 200-1880 230-570Elastic modulus (GPa) 85 230-400 190-210 70-79Elongation to break (%) 3.5 1.4 10-32 10-25Density ( g

cm3 ) 2.5 1.8 7.85 2.7Relative cost 3.8+ 52-285 1 3

Table A.1: Properties of aluminium against other materials[3][4]

Types and Applications: Aluminium sheet thicknesses are classified by gauge and the al-loying additions are classified by different numbered series from 1xxx to 8xxx, where the ”xxx”specifies a particular manufacturing process for that series.

6xxx and 7xxx series alloys are used for aluminium bumpers because of their high strength.Age-hardened 6xxx series alloys are used as body closures such as bonnets, roofs and doorpanels because of good formability, dent resistance, corrosion resistance and surface appearance.Aluminium structural components use precipitate hardened 6xxx series alloys to achieve the highstrength and stiffness requirements.

53

Aluminium also has better energy absorption properties than steel in crash situations. Analuminium crush can is as effective as a steel crush can but only weighs half the amount.

Glass Reinforced Plastic (GRP)

The two most common components used to produce a GRP are polyester and E-glass fibres.Alternatives to polyester include vinylesters and epoxies while S-glass and C-glass fibres canalso be used as reinforcements for different applications. The properties of GRP are greatlydependent on the type of fibre used, the orientation of that fibre and the proportion used in themix.[14]

Property E-Glass S-Glass Carbon Aramid (Kevlar 49)

Tensile strength (MPa) 3450 4600 3800-6530 3600-4100Elastic modulus (MPa) 73 85 230-400 131Elongation to break (%) 3.5 3.5 1.4 2.5Density ( g

cm3 ) 2.58 2.5 1.8 1.44Relative cost 3.7 3.8+ 52-285 44

Table A.2: Properties of different glass fibre reinforcements against other fibre materials

• Low cost

• High production rates

• High strength

• High stiffness

• Relatively low density

• Non-flammable

• Resistant to heat

• Good chemical resistance

• Relatively insensitive to moisture

• Maintains strength over a wide range of conditions

• Good electrical insulation

Carbon Fibre

The current level of carbon fibre technology can produce amazingly strong components withthe least amount of weight, however they do still have their drawbacks. They are relativelyexpensive and a recent global shortage in carbon fibre means that prices are higher.

Properties: The mechanical properties of carbon fibre are dominated by the fibres used andthe fibre architecture as stated above. The ultimate strength and weight of a component is alsodependent on the skill with which the laminate is designed and manufactured. Performanceis significantly compromised by dry fibres, air pockets and gaps between plies. Consequently

54

Property Average Grade Carbon Fibre High Tensile Steel

Tensile Strength (GPa) 3.50 1.30Tensile Modulus (GPa) 230.00 210.00Specific Density 1.75 7.87Specific Strength 2.00 0.17

Table A.3: Comparison of carbon fibre properties against steel[15]

the properties presented in Table 3 and Table 4 are general and may differ depending on themanufacturer.

As can be seen, carbon fibre has a tensile strength almost 3 times greater than that of steel,yet is 4.5 times less dense.

There are many different grades of carbon fibre available, with differing properties, whichcan be used for specific applications.

Type Tensile Strength (GPa) Tensile Modulus (GPa)

High Tenacity 4.0 240Ultra High Tenacity 4.8 240Intermediate Modulus 6.0 290High Modulus 3.5 375Ultra High Modulus 3.4 425High Modulus/Tenacity 3.9 400

Table A.4: Types of carbon fibre[5]

Other desirable physical properties of carbon fibre and other composites include its resistanceto corrosion, fire and high stress tolerance levels as well as its chemical inertness. The beauty ofcarbon fibre is that it can be fabricated in such a way that directional performance (in terms ofresponse to force applied) can be manipulated to give the best possible results in virtually everycircumstance. The ability to arrange fibres to suit the particular forces affecting a componentmean more areas of weakness can be eliminated.

Kevlar

Kevlar is the registered trade name of a type of aramid that consists of long polymeric chainswith a parallel orientation made by DuPont. Kevlar obtains its strength from intermolecularbonds and stacking interactions between aromatic groups in neighbouring strands. Kevlarconsists of quite rigid molecules, which form a planar sheet-like structure similar to silk. Itgives excellent resistance to piercing. Kevlar’s main weaknesses are that it degrades in alkalineconditions or when exposed to chlorine. While it can have a great tensile strength, sometimesin excess of 4000 MPa, like all fibres it tends to buckle in compression.

Manufacturing: Kevlar can be bought in pre-woven fabric matts just like carbon fibre. Thelayup process for Kevlar follows exactly that of carbon fibre whether using a wet layup orpre-impregnated fibres.

55

In structural applications, namely body panels, Kevlar fibres can be bonded to one anotheror to other materials to form a composite material. It can be used together with carbon fibresin a hybrid weave in which carbon fibres are in one direction of weave and Kevlar is woven inthe other direction. This allows the properties of both carbon and Kevlar fibres to be utilised.

Property Kevlar 29 Kevlar 49

Density (g/cm3) 1.44 1.44Breaking Tenacity (MPa) 2920 3000Tensile Modulus (MPa) 70500 112400Tensile Strength - epoxy impregnated strands (MPa) 3600 3600Tensile Modulus - epoxy impregnated strands (MPa) 83000 124000

Table A.5: Properties of Kevlar

From the table, in comparison to some of the other materials, Kevlar has some great benefitsfor structural applications. However, it can be difficult to work with and requires special cuttingtools due to its high toughness.

A.2 Core Materials

Woods

Balsa is the most common wood core having first been used in early plane design sandwichedbetween sheets of aluminium. It has high compressive strength but suffers as a solution to racecar design due to its high density (> 100 kg/m3).

Honeycomb[8]

Aluminium honeycomb comes in at around the same cost (base level version) as the abovementioned foam however its properties are considerably better. It has the greatest strength perunit weight of all honeycombs, and provides excellent energy absorbing properties particularlyrelevant to vehicular crash safety.

The most common cell structure of honeycomb is a regular hexagonal shape with cell sizesranging from 1/8” up to 3/8” and cell wall thicknesses of between 0.0007” and 0.006”. Depend-ing on wall/cell sizes the density is usually less than 100 kg/m3.

Typical aluminium alloys used for the honeycombs are 5052, 5056 and a few lower cost 3000series alloys. The 5000 series alloys are aerospace grade, the difference between 5052 and 5056being 5056 gives around 20% higher strength than 5052, but comes at a higher premium. 3000series are lower in cost still.

Aramid honeycombs are effectively paper that has been dipped in phenolic resin leading tovery high strength, excellent flame resistance but the cost is usually more than twice that ofaluminium honeycomb and aluminium is stiffer.

Common aramid honeycombs are Nomex and Kevlar, with densities mostly less than alu-minium derivatives.

56

B Preliminary Testing

B.1 Rohacell

We were not able to get extensive test data from Rohacell as their material has never beenused in this particular type of application. Along with the lack of simulation data we neededto perform tests on material samples in order to get an idea of how this material may workin our crash structure. Similarly to our test of the original crash structure, we performed astatic crush test on a plain cylindrical sample. In addition, we performed a dynamic test ona plain sample using a drop tower and due to our layered and bonded design we decided toperform an additional dynamic crush test to evaluate the effects of a layer of Araldite 420epoxy approximately 1mm thick down the center of the sample. This epoxy cures at roomtemperature, but the sample was given a slight heat treatment to speed the curing process, thisshould have an insignificant effect on the final strength of the bond or the foam.

B.1.1 Static Crush Test

This test was performed in a hydraulic press and placed under a constant displacement of 5mmper minute and the load was recorded as a function of the displacement. The diameter of thecylinder was 80mm and the height was 75mm.

It would be interesting to overlay the manufacturer’s compressive strength value on top ofthe data obtained as a reference, but that information was unavailable. We were hoping to getsamples of Rohacell 110 IG to test as that was the material which we were planning on using forour structure, but instead it was a slightly lower grade which they do not sell commercially andwe had relate these results to Degussa’s datasheets. We can reasonably estimate the compressivestrength at the beginning of the crushing plateau, which gives us a value for σc = 2.44 MPa,whereas the manufacturer lists it as σc = 3.0 MPa. In the end the results correlated well withour potential material choice.

The material exhibits a steady behaviour until it reaches full densification at 51mm, approx-imately 32% of the initial value. Prior to reaching full densification, 637 J have been absorbedwhich is equivalent to 15.75 kJ

m3 , corresponding to an average engineering stress of 2.53 MPa.

For our application, it is also important to note that the material remains intact as asingle block and there is no obvious failure, the energy seems to be only absorbed through thecompaction of the foam.

57

(a) Energy and Stress (b) Compacted Sample

Figure B.1: Static Crush on a Sample of Rohacell 110IG, ø79 mm

B.1.2 Impact Test

The two following impact tests were performed in a drop tower with a mass of 40 kg and avelocity of 7m

swhich result in a total energy of 1 kJ .

The plain sample behaved similarly to the static test, other than some pieces which frag-mented of the sides. However, this could be due to additional energy applied after reaching fullcompaction of the material when it was become more brittle. The total energy absorbed bythis sample is less than the static test with a value of 512 J (12.3 kJ

m3 ), resulting in an averageengineering stress of 2.21 MPa. The final length of the sample is 37% of the original sample.

The second bonded sample also behaved very much like the first, expect for some crackswhich initiated at the bond layer. Again it is hard to determine if this happened before or afterreaching the fully compacted length. The total energy absorbed in this sample is slightly lowerat 481 J (12.8 kJ

m3 ), but because the sample size is slightly smaller in diameter, 76 mm vs 80 mmfor the plain sample, it has an average engineering stress of 2.30 MPa. The resulting lengthafter this impact is 38%, very similar to the first impact test.

Overall, we see a bit of a drop in energy absorption when it came time to the dynamic testsbut the material still fared well and gave linear and stable results. There was some failure ofthe material but it was mainly restricted to the periphery and may have only occurred afterreaching full compaction. The bond line in the second sample which was originally a possiblesource of weakness has been proven to withstand the impact and not have a significant effecton the energy absorbed in the compression.

58

(a) Energy and Stress (b) Compacted Sample

Figure B.2: Drop Test on a Plain Sample of Rohacell 110IG, ø80 mm

(a) Energy and Stress (b) Compacted Sample

Figure B.3: Drop Test on a Bonded Sample of Rohacell 110IG, ø76 mm

59

Figure B.4: Collection of Rohacell Samples

60

C Manufacturing Costs

61

Part No Unit Price No requ'd Delivery Total CostFFS-10 £279/m² 0,5 m² Degussa £139,50FFS-10 £68,25/kg 200g - £13,65FFS-21 £2,65/m 960mm - £2,54FFS-22 £2,65/m 415mm - £1,10FFS-231 £2,65/m 200mm - £0,53FFS-232 £2,65/m 200mm - £0,53FFS-24 £20,68/m² 0,056m² - £1,16FFS-25 £20,68/m² 0,0075m² £0,15FFS-26 £20,68/m² 0,0062m² - £0,13FFS-27 £20,68/m² 0,053m² - £1,10FFS-28 £20,68/m² 0,0756m² - £1,56FFS-30 £0,26 2 1 day £0,52FFS-31 £0,06 2 1 day £0,12FFS-32 £0,06 4 1 day £0,24FFS-30 £0,26 2 1 day £0,52

Signed DateTeam Spirit 19.3.07

£163,35

Mild steel tube (25x25x2,5)

Mild steel tube (25x25x3)mild steel plate 280mmx200mmx3mm

Washer M6

Comments

TOTAL Bill of materials

Mild steel tube (25x25x3)

mild steel plate 393mmx135mmx1,5mmmild steel plate 560mmx135mmx1,5mm

mild steel plate 300mmx25mx3mmmild steel plate 310mmx20mmx3mm

Allen Bolt M6x35

Bill Of Material

DescriptionRohacell 110 IG (75mm)

Mild steel tube (25x25x2,5)

Allen Bolt M6x20

Nut M6

Bill of Material

Part Crash Box

Formula Ford Spirit

PrototypeSub Assembly

Araldite 420

Part No Unit Price No requ'd Delivery Total CostFFS-10 - 1 Rohacell £199,07

FFS-20 - 1 internal £43,05FFS-21 - 1 internal £22,63FFS-22 - 4 internal £9,30FFS-231 - 8 internal £4,63FFS-232 - 8 internal £4,63FFS-24 - 1 internal £10,18FFS-25 - 2 internal £6,71FFS-26 - 6 internal £8,74FFS-27 - 2 internal £8,48FFS-28 - 2 internal £8,94

FFS-30 £0,26 2 1 day £0,52FFS-31 £0,06 2 1 day £0,12FFS-32 £0,06 4 1 day £0,24FFS-30 £0,26 2 1 day £0,52

240,6£140,35£24,06

TOTAL for Proto Crash Box

Signed Date

Prototype

£327,76

Sub Assembly

FrameTubes

Lateral Reinforcement triangelsFront Plate

Washer M6

Comments

Team Spirit 19.3.07

Bill Of Material

DescriptionRohacell Nose Cone

2nd Bulkhead

Total Labour time (min)Total £ LabourTotal £ Machine

Allen Bolt M6x20

Nut M6

Side FenceTop Fence

Costing Tender

Part Crash Box

Formula Ford Spirit

Internal Reinforcement triangels

Reinforcement PlatesAttachment Brackets

Allen Bolt M6x35

Part No Unit Price No requ'd Delivery Total Cost£279/m² 0,5 m² - £139,50£68,25/kg 200g - £13,65

Op No Mach/dept Time (min) Cost10 5 £2,92

£0,5020 17 £9,92

£1,70

30 26 £15,17£2,60

40 8 £4,67£0,80

56 -11,2

Total estimated time (min) 67,2

£153,15£35/h £39,20£6/h £6,72

£199,07

Op 10:

op 30:op 40:

Signed Date

Amount of Araldite --> Surface area= 0,38m²*0,6=0,228kg

Op 20:

Amount of Araldite --> Surface area= 0,056m²*0,6=0,0336kg

Addition of Time (min)

Total Raw MaterialsTotal £ LabourTotal £ Machine

20% set-up allowance (min)

TOTAL nose cone

Curing time for Glue: to check on Araldite spec sheet 'Redux420'

Sub Assembly

Costing Tender

Part

Comments

Araldite 420 A+B, brush, scales

Bill Of Material

DescriptionRohacell 110 IG (75mm)Araldite 420

Tools required

Draw form from templates on bonded block and cut out form

Bandsaw

Glue block on secondary bulkhead (FFS-20P), using Araldite 420.

Team Spirit 19.3.07

Print forms: see nosecone drawings in attachment

Operation

Bandsaw

Glue blocks together with Araldite 420 , put under pressure for better curing

Printed forms

Araldite 420 A+B, brush, scales

Araldite: 10 parts Araldite 420A over 4 parts Araldite 420B (measured by weight)

Formula Ford SpiritNose Cone Sheet 1/1Nose Cone Part n° FFS-10

Cut out 3 blocs of 280x500mm

Part No Unit Price No requ'd Delivery Total CostFFS-21 £22,63 1 intern £22,63FFS-22 £2,32 4 intern £9,30FFS-231 £1,16 4 intern £4,63FFS-232 £1,16 4 intern £4,63FFS-24 £10,18 1 intern £10,18FFS-25 £3,36 2 intern £6,71FFS-26 £1,46 6 intern £8,74FFS-27 £1,41 2 intern £8,48FFS-28 £1,49 2 intern £8,94

Op No Mach/dept Time (min) Cost10 9,6 £5,60

£0,96

20 23 £13,44£2,30

30 2 £1,12£0,20

40 6,3 £3,64£0,63

50 3 £1,75£0,30

60 8,6 £5,04£0,86

52,5 -£35/h 10,5

Total estimated time (min) 63

£6/h £36,75£6,30

£43,05

£104,98

Op 10:

MIG/TIG

Addition of Time (min)20% set-up allowance (min)

Total £ LabourTotal £ Machine

Subtotal Bulkhead

Weld triangles (FFS-231 and FFS-232) to Frame (FFS-21) and tubes (FFS-22) as shown in DWg FFS-20P

MIG/TIG

weld tubes (FFS-22) to the frame (FFS-21), as shown in Dwg FFS-20P

MIG/TIG

Internal Reinforcement Triangles

Front Plate

Side Fence

Operation

Top Fence

Brackets

Lateral Reinforcement Triangles

Comments

Tools required

Weld the brackets (FFS-26) to the Frame (FFS-21) using bulkhead as a Jig

MIG/TIG-

Primary Bulkhead

Put Frame on primary Bulkhead and bolt the brackets (FFS-26) to the Bulkhead.

Weld reinforcement plates (FFS-25) to the Frame (FFS-21) as shown in Dwg FFS-20P

SAE estimate welding at 0,14£/cm. Total surface=(2,5*2+2,5*2)= 10cm*4 (4 tubes) = 40cm*0,14£/cm= £5,6 (SAE)

-

Bill Of Material

DescriptionFrameTubes

-

-

Weld front plate (FFS-24) to frame (FFS-21) as shown in Dwg FFS-20P

Formula Ford SpiritBulkhead Sheet 1/1

Costing Tender

PartFFS-20

Reinforcement Plates

TOTAL Bulkhead

Allen key, spanner

Sub Assembly

MIG/TIG

Part n°

Op 20:

Op 30:

Op 40:

Op 60:

Signed DateTeam Spirit 19.3.07

SAE estimate welding at 0,14£/cm. Total surface=(2,5*2+3,5*2)= 12cm*8 (8 triangels) = 96cm*0,14£/cm= £13,44 (SAE)SAE estimate welding at 0,14£/cm. Total surface=(8mm/hole)= 0,8cm*10 (10 holes) = 8cm*0,14£/cm= £1,12 (SAE)SAE estimate welding at 0,14£/cm. Total surface=(2,5*2+2*4)= 13cm*2 (2 plates) = 26cm*0,14£/cm= £3,64 (SAE)

SAE estimate welding at 0,14£/cm. Total surface=(3*2)= 6cm*6 (6 plates) = 36cm*0,14£/cm= £5,04 (SAE)

Part No Unit Price No requ'd Delivery Total Cost£2,65/m 960mm - £2,54

Op No Mach/dept Time (min) Cost10 5 £2,92

£0,5020 5 £2,92

£0,50

30 11,5 £6,72£1,15

40 3 £1,75£0,30

24,5 -4,9

Total estimated time (min) 29,4

£2,54£35/h £17,15£6/h £2,94

£22,63

Op 10:Op 20:Op 30:Op 40:

Op 50:

Signed Date

Costing Tender

-

MIG/TIG welder

Formula Ford SpiritPart

Sub Assembly

Operation Tools required

Total £ Labour

Cut 2 tubes to a length of 280mm, with both ends chamfered to 45° as shown in Dwg FFS-211

band saw

19.3.07

Time for grinding estimated at 3 min (SAE)

Bill Of Material

DescriptionMild steel tube (25x25x2,5)

Cut 2 tubes to a length of 196,5mm, both ends chamfered to 45° as shown in Dwg FFS-212

Grind front surface even

weld tubes perpendicular together as shown in Dwg FFS-21

Team Spirit

angle grinder

Total Raw Materials

MIG/TIG

-

Addition of Time (min)20% set-up allowance (min)

band saw

SAE estimate welding at 0,14£/cm. Total surface=(2,5+2,5+3,5+3,5)= 12cm*4 (4 tubes) = 48cm*0,14£/cm= £6,72 (SAE)

Total £ MachineTOTAL

Time for cutting tube estimated at 5 min (SAE)

Time for cutting tube estimated at 5min (SAE)Time for cutting tube estimated at 5 min (SAE)

CommentsSee Dwg FFS-21, FFS-211, FFS-212

BulkheadFrame Part n° FFS-21

Sheet 1/1

Part No Unit Price (/m) No requ'd Delivery Total Cost£2,65/m 415mm - £1,10

Op No Mach/dept Time (min) Cost10 7 £4,08

£0,70

20 3 £1,75£0,30

10 -2

Total estimated time (min) 12

£1,10£35/h £7,00£6/h £1,20

£9,30

Op 20:Op 30:

Signed Date

Costing Tender

angle grinder

20% set-up allowance (min)

TOTAL

Formula Ford Spirit

Bill Of Material

Description

Part

Team Spirit 19.3.07

Addition of Time (min)

Time for de-burring estimated at 3min (SAE)Time for cutting estimated at 5min (SAE)

Comments

Total Raw MaterialsTotal £ Labour

de-burr end of tubes using angle grinder

Mild steel tube (25x25x2,5)

Sub Assembly

Cut 4 tubes to a length of 103mm, with an angle of 6° as shown in Dwg FFS-22

Band Saw -

Operation

See Dwg FFS-22

Lime / angle grinder: grinding disc

Total £ Machine

Bulkhead Sheet 1/1Tubes Part n° FFS-22

Tools required

Part No Unit Price No requ'd Delivery Total Cost£2,65/m 200mm - £0,53

Op No Mach/dept Time (min) Cost10 3 £1,75

£0,30

20 2 £1,17£0,20

5 -1

Total estimated time (min) 6

£0,53£35/h £3,50£6/h £0,60

£4,63

Op 20:Op 30:

Signed Date

Bill Of Material

Description

Addition of Time (min)

Total Raw MaterialsTotal £ LabourTotal £ Machine

20% set-up allowance (min)

TOTAL

Formula Ford Spirit

Mild steel tube (25x25x3)

Team Spirit 19.3.07

Sub Assembly

Costing Tender

Part

Time for de-burring estimated at 2min (SAE)Time for cutting estimated at 3min (SAE)

Comments

Tools required

de-burr tubes all around using angle grinder

angle grinder

OperationCut tube to 4 lengths of 48,5mm, with 48° angles on both ends as shown in Dwg FFS-231

Band Saw

Bulkhead Sheet 1/1Internal R Triangles Part n° FFS-231

See Dwg FFS-231

-

Lime / angle grinder: grinding disc

Part No Unit Price No requ'd Delivery Total Cost£2,65/m 200mm - £0,53

Op No Mach/dept Time (min) Cost10 3 £1,75

£0,30

20 2 £1,17£0,20

5 -1

Total estimated time (min) 6

£0,53£35/h £3,50£6/h £0,60

£4,63

Op 20:Op 30:

Signed Date

Bulkhead Sheet 1/1Lateral R Triangles Part n° FFS-232

de-burr tubes all around using angle grinder

angle grinder

OperationCut tube to 4 lengths of 44mm, with both 45° angles on both ends as shown in Dwg FFS-232

Band Saw -

Lime / angle grinder: grinding disc

Time for de-burring estimated at 2min (SAE) see Dwg FFS-232Time for cutting estimated at 3min (SAE) see Dwg FFS-232

Comments

Tools required

TOTAL

Formula Ford Spirit

Mild steel tube (25x25x3)

Team Spirit 19.3.07

Sub Assembly

Costing Tender

Part

See Dwg FFS-232

Bill Of Material

Description

Addition of Time (min)

Total Raw MaterialsTotal £ LabourTotal £ Machine

20% set-up allowance (min)

Part No Unit Price No requ'd Delivery Total Cost£20,68/m² 0,056m² - £1,16

Op No Mach/dept Time (min) Cost10 3 £1,75

£0,3020 5 £2,92

£0,5030 3 £1,75

£0,30

11 -2,2

Total estimated time (min) 13,2

£1,16£35/h £7,70£6/h £1,32

£10,18

Op 10:Op 20:Op 30:

Signed Date

20% set-up allowance (min)

TOTAL

Time for cutting plate estimated at 3min (SAE)

Comments

Total Raw MaterialsTotal £ LabourTotal £ Machine

Time for drilling estimated at 5min (SAE)

de-burr holes and outline plate using angle grinder and de-burring tool

angle grinder

Drill 10 holes of 8mm dia in plate as shown in Dwg

Pillar drill Pillar drill, drill 8mm dia

Cut out plate 280x196,5x3mm as shown on Dwg FFS-24

Cutting saw-

Operation

Group D 19.3.07

Time for chamfering estimated at 3min (SAE)

Lime / angle grinder: grinding disc / de-burring tool

See Dwg FFS-24

Addition of Time (min)

Bill Of Material

Descriptionmild steel plate 280mmx200mmx3mm

Tools required

Front Plate Part n° FFS-24

Costing Tender

Part Bulkhead Sheet 1/1

Formula Ford Spirit

Sub Assembly

Part No Unit Price No requ'd Delivery Total Cost£20,68/m² 0,0075m² £0,15

Op No Mach/dept Time (min) Cost10 5 £2,92

£0,5020 3 £1,75

£0,308 -

1,6Total estimated time (min) 9,6

£0,15£35/h £5,60£6/h £0,96

£6,71

Op 10:Op 20:

Signed Date

Costing Tender

Cut out 2 plates 146,5x25x3mm as shown on Dwg FFS-25

Cutting saw-

Formula Ford Spirit

Bill Of Material

Description

Group D 19.3.07

See Dwg FFS-25

TOTAL

Part

Time for chamfering estimated at 3 min (SAE)Time for cutting plate estimated at 5 min (SAE)

Comments

Tools required

mild steel plate 300mmx25mx3mm

Sub Assembly

Addition of Time (min)

Operation

Lime / angle grinder: grinding disc

Total £ Machine

Total Raw MaterialsTotal £ Labour

de-burr outline plates using angle grinder

angle grinder

20% set-up allowance (min)

Bulkhead Sheet 1/1Reinforcement Plates Part n° FFS-25

Part No Unit Price No requ'd Delivery Total Cost£20,68/m² 0,0062m² - £0,13

Op No Mach/dept Time (min) Cost20 3 £1,75

£0,3030 2 £1,17

£0,2040 2,5 £1,46

£0,2550 3 £1,75

£0,3010,5 -2,1

Total estimated time (min) 12,6

£0,13£35/h £7,35£6/h £1,26

£8,74

Op 20:Op 30:Op 40:Op 50:

Signed Date

20% set-up allowance (min)

TOTAL

Addition of Time (min)

Total Raw MaterialsTotal £ LabourTotal £ Machine

See Dwg FFS-26

Drill 6x7mm holes in the plate as shown on Dwg FFS-26

pillar drill7mm drill

Operation Tools required

Chamfer edges on plates

circle Saw-

Lime / angle grinder: grinding disc

Cut plate to pieces of 60x20x3mm (5 cuts)

Chamfer holes on both sides using de-burring tool

pillar drillde-burring tool

Group D 19.3.07

Descriptionmild steel plate 310mmx20mmx3mm

Time estimated for chamfering at 3min (SAE)Time for cutting estimated at 2,5min (SAE)Time for chamfering estimated at 2min (SAE)Time for Pillar drill estimated at 3min (SAE)

Comments

Part n°

Bill Of Material

PartFFS-26

Formula Ford Spirit

Sub Assembly

Costing Tender

angle grinder

Bulkhead Sheet 1/1Brackets

Part No Unit Price No requ'd Delivery Total Cost£20,68/m² 0,053m² - £1,10

Op No Mach/dept Time (min) Cost10 3 £1,75

£0,3020 4 £2,33

£0,4030 2 £1,17

£0,20

9 -1,8

Total estimated time (min) 10,8

£1,10£35/h £6,30£6/h £1,08

£8,48

Op 10:Op 20:Op 30:

Signed Date

Side Fence Part n° FFS-27

Costing Tender

Part Bulkhead Sheet 1/1

Formula Ford Spirit

Sub Assembly

Descriptionmild steel plate 393mmx135mmx1,5mm

Tools requiredOperation

Group D 19.3.07

Time for chamfering estimated at 2min (SAE)

Addition of Time (min)

Total Raw Materials

Cut out 2 plates of 196,5mm long and 135mm wide as shown in Dwg FFS-27

Cutting saw -

20% set-up allowance (min)

de-burr holes and outline plate using angle grinder and de-burring tool

angle grinder

Drill 3 holes of 8mm dia in each plate as shown in Dwg FFS-27

Pillar drill Pillar drill, drill 8mm dia

Lime / angle grinder: grinding disc / de-burring tool

Bill Of Material

Time for cutting plate estimated at 3min (SAE)

Comments

Time for drilling estimated at 4min (SAE)

Total £ LabourTotal £ Machine

See Dwg FFS-27

TOTAL

Part No Unit Price No requ'd Delivery Total Cost£20,68/m² 0,0756m² - £1,56

Op No Mach/dept Time (min) Cost10 3 £1,75

£0,3020 4 £2,33

£0,4030 2 £1,17

£0,20

9 -1,8

Total estimated time (min) 10,8

£1,56£35/h £6,30£6/h £1,08

£8,94

Op 10:Op 20:Op 30:

Signed Date

Total £ LabourTotal £ Machine

TOTAL

Time for cutting plate estimated at 3min (SAE)

Comments

Time for drilling estimated at 5min (SAE)

See Dwg FFS-28

de-burr holes and outline plate using angle grinder and de-burring tool

angle grinder

Drill 2 holes of 8mm dia in each plate as shown in Dwg FFS-28

Pillar drill Pillar drill, drill 8mm dia

Lime / angle grinder: grinding disc / de-burring tool

Bill Of Material

Addition of Time (min)

Total Raw Materials

Cut out 2 plates of 280mm long and 135mm wide as shown in Dwg FFS-28

Cutting saw -

20% set-up allowance (min)

Group D 19.3.07

Time for chamfering estimated at 3min (SAE)

Descriptionmild steel plate 560mmx135mmx1,5mm

Tools requiredOperation

Top Fence Part n° FFS-28

Costing Tender

Part Bulkhead Sheet 1/1

Formula Ford Spirit

Sub Assembly

3

83,50

FFS-21

FFS-25

FFS-24

280

102

102,5

300

3

95,60°

FFS-231

FFS-28

196,50

171,50

12,65

FFS-232

FFS-22 FFS-27

FFS-26

D

E

F

C

1 2 3 4

B

A

321 5

C

D

4 6 7 8

A

B

2nd Bulkhead Proto

Spirit Racing Cars

WEIGHT:

A3

SHEET 1 OF 1SCALE:1:5

DWG NO.

TITLE:

REVISIONDO NOT SCALE DRAWING

MATERIAL:

FFS-20P

196,50

280

45°

FFS-211

FFS-212

FFS-211

FFS-212

2

FFS-24

B

C

D

1 2

A

321 4

B

A

5 6

DRAWN

CHK'D

APPV'D

MFG

Q.A

UNLESS OTHERWISE SPECIFIED:

DIMENSIONS ARE IN MILLIMETERS

SURFACE FINISH:

TOLERANCES:

LINEAR:

ANGULAR:

FINISH: DEBUR AND

BREAK SHARP

EDGES

NAME SIGNATURE DATE

MATERIAL:

DO NOT SCALE DRAWING REVISION

TITLE:

DWG NO.

SCALE:1:5 SHEET 1 OF 1

A4

C

WEIGHT:

Frame

FFS-21

Spirit Racing Cars

Steel

45°

280

Tube thickness: 2.5mm

B

C

D

1 2

A

321 4

B

A

5 6

DRAWN

CHK'D

APPV'D

MFG

Q.A

UNLESS OTHERWISE SPECIFIED:

DIMENSIONS ARE IN MILLIMETERS

SURFACE FINISH:

TOLERANCES:

LINEAR:

ANGULAR:

FINISH: DEBUR AND

BREAK SHARP

EDGES

NAME SIGNATURE DATE

MATERIAL:

DO NOT SCALE DRAWING REVISION

TITLE:

DWG NO.

SCALE:1:5 SHEET 1 OF 1

A4

C

WEIGHT:

Frame top tube

FFS-21125CD4

Spirit Racing Cars

45°

196,50

Tube thickness: 2.5mm

B

C

D

1 2

A

321 4

B

A

5 6

DRAWN

CHK'D

APPV'D

MFG

Q.A

UNLESS OTHERWISE SPECIFIED:

DIMENSIONS ARE IN MILLIMETERS

SURFACE FINISH:

TOLERANCES:

LINEAR:

ANGULAR:

FINISH: DEBUR AND

BREAK SHARP

EDGES

NAME SIGNATURE DATE

MATERIAL:

DO NOT SCALE DRAWING REVISION

TITLE:

DWG NO.

SCALE:1:5 SHEET 1 OF 1

A4

C

WEIGHT:

Frame side tube

FFS-21225CD4

Spirit Racing Cars

6°

103

Tube thickness: 2.5mm

B

C

D

1 2

A

321 4

B

A

5 6

DRAWN

CHK'D

APPV'D

MFG

Q.A

UNLESS OTHERWISE SPECIFIED:

DIMENSIONS ARE IN MILLIMETERS

SURFACE FINISH:

TOLERANCES:

LINEAR:

ANGULAR:

FINISH: DEBUR AND

BREAK SHARP

EDGES

NAME SIGNATURE DATE

MATERIAL:

DO NOT SCALE DRAWING REVISION

TITLE:

DWG NO.

SCALE:2:1 SHEET 1 OF 1

A4

C

WEIGHT:

Side tube

FFS-2225CD4

Spirit Racing Cars

22

48,5

48°

48°

3

25

C

2 31 4

B

A

D

E

F

Internal reinforcement triangles

WEIGHT:

A4

SHEET 1 OF 1SCALE:1:1

DWG NO.

TITLE:

REVISIONDO NOT SCALE DRAWING

MATERIAL:

DATESIGNATURENAME

DEBUR AND

BREAK SHARP

EDGES

FINISH:UNLESS OTHERWISE SPECIFIED:

DIMENSIONS ARE IN MILLIMETERS

SURFACE FINISH:

TOLERANCES:

LINEAR:

ANGULAR:

Q.A

MFG

APPV'D

CHK'D

DRAWN

FFS-23125CD4

Spirit Racing Cars

22

44

45°

45°

25

3

C

2 31 4

B

A

D

E

F

Lateral reinforcement triangles

WEIGHT:

A4

SHEET 1 OF 1SCALE:2:1

DWG NO.

TITLE:

REVISIONDO NOT SCALE DRAWING

MATERIAL:

DATESIGNATURENAME

DEBUR AND

BREAK SHARP

EDGES

FINISH:UNLESS OTHERWISE SPECIFIED:

DIMENSIONS ARE IN MILLIMETERS

SURFACE FINISH:

TOLERANCES:

LINEAR:

ANGULAR:

Q.A

MFG

APPV'D

CHK'D

DRAWN

FFS-23225CD4

Spirit Racing Cars

196,50

280

Thickness: 3mm

B

C

D

1 2

A

321 4

B

A

5 6

DRAWN

CHK'D

APPV'D

MFG

Q.A

UNLESS OTHERWISE SPECIFIED:

DIMENSIONS ARE IN MILLIMETERS

SURFACE FINISH:

TOLERANCES:

LINEAR:

ANGULAR:

FINISH: DEBUR AND

BREAK SHARP

EDGES

NAME SIGNATURE DATE

MATERIAL:

DO NOT SCALE DRAWING REVISION

TITLE:

DWG NO.

SCALE:1:5 SHEET 1 OF 1

A4

C

WEIGHT:

Front Plate

FFS-24mild-steel

Spirit Racing Cars

25

146,50

thickness: 3mm

B

C

D

1 2

A

321 4

B

A

5 6

DRAWN

CHK'D

APPV'D

MFG

Q.A

UNLESS OTHERWISE SPECIFIED:

DIMENSIONS ARE IN MILLIMETERS

SURFACE FINISH:

TOLERANCES:

LINEAR:

ANGULAR:

FINISH: DEBUR AND

BREAK SHARP

EDGES

NAME SIGNATURE DATE

MATERIAL:

DO NOT SCALE DRAWING REVISION

TITLE:

DWG NO.

SCALE:1:5 SHEET 1 OF 1

A4

C

WEIGHT:

Reinforcement plate

FFS-25mild steel

Spirit Racing Cars

36°

20

R10

7

40 12,50

B

C

D

1 2

A

321 4

B

A

5 6

DRAWN

CHK'D

APPV'D

MFG

Q.A

UNLESS OTHERWISE SPECIFIED:

DIMENSIONS ARE IN MILLIMETERS

SURFACE FINISH:

TOLERANCES:

LINEAR:

ANGULAR:

FINISH: DEBUR AND

BREAK SHARP

EDGES

NAME SIGNATURE DATE

MATERIAL:

DO NOT SCALE DRAWING REVISION

TITLE:

DWG NO.

SCALE:2:1 SHEET 1 OF 1

A4

C

WEIGHT:

Attachment bracket

FFS-26mild steel

Spirit Racing Cars

135

196,50

thickness: 1.5mm

B

C

D

1 2

A

321 4

B

A

5 6

DRAWN

CHK'D

APPV'D

MFG

Q.A

UNLESS OTHERWISE SPECIFIED:

DIMENSIONS ARE IN MILLIMETERS

SURFACE FINISH:

TOLERANCES:

LINEAR:

ANGULAR:

FINISH: DEBUR AND

BREAK SHARP

EDGES

NAME SIGNATURE DATE

MATERIAL:

DO NOT SCALE DRAWING REVISION

TITLE:

DWG NO.

SCALE:1:5 SHEET 1 OF 1

A4

C

WEIGHT:

Side fence

FFS-27mild steel

Spirit Racing Cars

280

135

Thickness: 1.5mm

B

C

D

1 2

A

321 4

B

A

5 6

DRAWN

CHK'D

APPV'D

MFG

Q.A

UNLESS OTHERWISE SPECIFIED:

DIMENSIONS ARE IN MILLIMETERS

SURFACE FINISH:

TOLERANCES:

LINEAR:

ANGULAR:

FINISH: DEBUR AND

BREAK SHARP

EDGES

NAME SIGNATURE DATE

MATERIAL:

DO NOT SCALE DRAWING REVISION

TITLE:

DWG NO.

SCALE:1:5 SHEET 1 OF 1

A4

C

WEIGHT:

Top fence

FFS-28mild steel

Spirit Racing Cars

Part No Unit Price No requ'd Delivery Total CostFFS-10 £279/m² 0,5 m² Degussa £139,50FFS-10 £68,25/kg 230g Huntsmann £15,70FFS-21 £2,65/m 960mm - £2,54FFS-221 £2,65/m 210mm - £0,53FFS-222 £2,65/m 90mm - £0,24FFS-231 £2,65/m 200mm - £0,53FFS-232 £2,65/m 200mm - £0,53FFS-24 £20,68/m² 0,056m² - £1,16FFS-25 £20,68/m² 0,0075m² - £0,15FFS-26 £20,68/m² 0,0062m² - £0,13FFS-27 £20,68/m² 0,0118m² - £0,24FFS-28 £20,68/m² 0,017m² - £0,35FFS-30 £0,26 2 1 day £0,52FFS-31 £0,06 2 1 day £0,12FFS-32 £0,06 4 1 day £0,24FFS-30 £0,26 2 1 day £0,52

Signed Date

mild steel plate 310mmx20mmx3mm

Allen Bolt M6x35

Mild steel tube (25x25x2)

mild steel plate 560mmx30mmx1mm

Mild steel tube (25x25x2)

mild steel plate 393mmx30mmx1mm

Nut M6

Bill of Material

Part Crash Box

Formula Ford Spirit

Final DesignSub Assembly

Araldite 420

mild steel plate 300mmx25mx2mm

Bill Of Material

DescriptionRohacell 110 IG (75mm)

Mild steel tube (25x25x2)

Comments

TOTAL Bill of materials

Allen Bolt M6x20

Team Spirit 19.3.07

£163,01

Mild steel tube (25x25x2)

Mild steel tube (25x25x2)mild steel plate 280mmx200mmx2mm

Washer M6

Part No Unit Price No requ'd Delivery Total CostFFS-10 - 1 Rohacell £206,86

FFS-20 - 1 internal £43,05FFS-21 - 1 internal £22,63FFS-221 - 2 internal £5,48FFS-222 - 2 internal £5,16FFS-231 - 8 internal £4,63FFS-232 - 8 internal £4,63FFS-24 - 1 internal £10,18FFS-25 - 2 internal £6,71FFS-26 - 6 internal £8,74FFS-27 - 1 internal £7,62FFS-28 - 1 internal £7,73

FFS-30 £0,26 2 1 day £0,52FFS-31 £0,06 2 1 day £0,12FFS-32 £0,06 4 1 day £0,24FFS-30 £0,26 2 1 day £0,52

251,4£146,65£25,14

TOTAL for Proto Crash Box

Signed Date

Costing Tender

Part Crash Box

Formula Ford Spirit

Bill Of Material

DescriptionRohacell Nose Cone

2nd Bulkhead

Total Labour time (min)Total £ LabourTotal £ Machine

Allen Bolt M6x20

Comments

Team Spirit 19.3.07

Final Design

£334,83

Sub Assembly

Frame

Top TubesInternal Reinforcement Triangels

Front Plate

Washer M6

Reinforcement Plates

Allen Bolt M6x35

Side FenceAttachment Brackets

Nut M6

Top Fence

Bottom Tubes

Lateral Reinforcement Triangels

Part No Unit Price No requ'd Delivery Total Cost£279/m² 0,5 m² - £139,50£68,25/kg 230g - £15,70

Op No Mach/dept Time (min) Cost10 12 £7,00

£1,2020 17 £9,92

£1,70

30 26 £15,17£2,60

40 8 £4,67

£0,8063 -

12,6Total estimated time (min) 75,6

£155,20£35/h £44,10£6/h £7,56

£206,86

Op 10:

op 30:op 40:

Signed Date

Araldite: 10 parts Araldite 420A over 4 parts Araldite 420B (measured by weight)

Formula Ford SpiritNose Cone Sheet 1/1Nose Cone Part n° FFS-10

Cut out 7 blocs of: 2x(280x200mm); 1x(275x200mm); 1x(250x200mm); 1x(220x200mm); 1x(185x200mm); 1x(150x200mm)

Glue blocks together with Araldite 420 , put under pressure for better curing

Printed forms

Araldite 420 A+B, brush, scales

Operation

Bandsaw

Team Spirit 19.3.07

Print forms: see nosecone drawings in attachment (FFS-11)

Comments

Araldite 420 A+B, brush, scales

Bill Of Material

DescriptionRohacell 110 IG (75mm)Araldite 420

Tools required

Draw form from templates on bonded block and cut out form

Bandsaw

Glue block on secondary bulkhead (FFS-20), using Araldite 420.

Sub Assembly

Costing Tender

Part

Amount of Araldite --> Surface area= 0,384²*0,6=0,230kg

Op 20:

Amount of Araldite --> Surface area= 0,056m²*0,6=0,0336kg

Addition of Time (min)

Total Raw MaterialsTotal £ LabourTotal £ Machine

20% set-up allowance (min)

TOTAL

Curing time for Glue: to check on Araldite spec sheet 'Redux420'

Part No Unit Price No requ'd Delivery Total CostFFS-21 £22,63 1 intern £22,63FFS-221 £2,74 2 intern £5,48FFS-222 £2,58 2 intern £5,16FFS-231 £1,16 4 intern £4,63FFS-232 £1,16 4 intern £4,63FFS-24 £10,18 1 intern £10,18FFS-25 £3,36 2 intern £6,71FFS-26 £1,46 6 intern £8,74FFS-27 £3,81 2 intern £7,62FFS-28 £3,87 2 intern £7,73

Op No Mach/dept Time (min) Cost10 9,6 £5,60

£0,96

20 23 £13,44£2,30

30 2 £1,12£0,20

40 6,3 £3,64£0,63

50 3 £1,75£0,30

60 8,6 £5,04£0,86

70 4 £5,04£0,40

52,5 -£35/h 10,5

Total estimated time (min) 63

£6/h £36,75£6,30

£43,05

£126,57

Weld the fences (FFS-27 and FFS-28) to the Frame (FFS-21) using bulkhead as a Jig

MIG/TIG Primary Bulkhead

FFS-20Sub Assembly Part n°

Primary Bulkhead

Reinforcement Plates

TOTAL Bulkhead

Allen key, spanner

MIG/TIG

Tools required

Weld the brackets (FFS-26) to the Frame (FFS-21) using bulkhead as a Jig

MIG/TIG-

Formula Ford SpiritBulkhead Sheet 1/1

Costing Tender

Part

-

Bill Of Material

DescriptionFrameBottom Tubes

-

-

Weld front plate (FFS-24) to frame (FFS-21) as shown in Dwg FFS-20F

Put Frame on primary Bulkhead and bolt the brackets (FFS-26) to the Bulkhead.

Weld reinforcement plates (FFS-25) to the Frame (FFS-21) as shown in Dwg FFS-20F

Front Plate

Brackets

Operationweld tubes (FFS-221 and FFS-222) to the frame (FFS-21), as shown in Dwg FFS-20F

MIG/TIG

Addition of Time (min)20% set-up allowance (min)

Total £ LabourTotal £ Machine

Subtotal Bulkhead

Top Tubes

Top Fence

Lateral Reinforcement Triangles

Side Fence

MIG/TIG

Weld triangles (FFS-231 and FFS-232) to Frame (FFS-21) and tubes (FFS-221 and FFS-222) as shown in Dwg FFS-20F

MIG/TIG

Internal Reinforcement Triangles

Op 10:

Op 20:

Op 30:

Op 40:

Op 60:

Signed Date

SAE estimate welding at 0,14£/cm. Total surface=(3*2)= 6cm*6 (6 plates) = 36cm*0,14£/cm= £5,04 (SAE)

SAE estimate welding at 0,14£/cm. Total surface=(2,5*2+2,5*2)= 10cm*4 (4 tubes) = 40cm*0,14£/cm= £5,6 (SAE)SAE estimate welding at 0,14£/cm. Total surface=(2,5*2+3,5*2)= 12cm*8 (8 triangels) = 96cm*0,14£/cm= £13,44 (SAE)SAE estimate welding at 0,14£/cm. Total surface=(8mm/hole)= 0,8cm*10 (10 holes) = 8cm*0,14£/cm= £1,12 (SAE)SAE estimate welding at 0,14£/cm. Total surface=(2,5*2+2*4)= 13cm*2 (2 plates) = 26cm*0,14£/cm= £3,64 (SAE)

Team Spirit 19.3.07

Comments

Part No Unit Price No requ'd Delivery Total Cost£2,65/m 960mm - £2,54

Op No Mach/dept Time (min) Cost10 5 £2,92

£0,5020 5 £2,92

£0,50

30 11,5 £6,72£1,15

40 3 £1,75£0,30

24,5 -4,9

Total estimated time (min) 29,4

£2,54£35/h £17,15£6/h £2,94

£22,63

Op 10:Op 20:Op 30:Op 40:

Op 50:

Signed Date

BulkheadFrame Part n° FFS-21

Sheet 1/1

Cut 2 tubes to a length of 196,5mm, both ends chamfered to 45° as in Dwg FFS-21

band saw

SAE estimate welding at 0,14£/cm. Total surface=(2,5+2,5+3,5+3,5)= 12cm*4 (4 tubes) = 48cm*0,14£/cm= £6,72 (SAE)

Total £ MachineTOTAL

Time for cutting tube estimated at 5min (SAE)Time for cutting tube estimated at 5 min (SAE) see Dwg FFS-212

Comments

Total £ Labour

Grind front surface even

-Operation Tools required

Bill Of Material

DescriptionMild steel tube (25x25x2)

weld tubes perpendicular together as shown in Dwg FFS-21

Team Spirit 19.3.07

angle grinder

Total Raw Materials

MIG/TIG

Time for grinding estimated at 3 min (SAE)

Addition of Time (min)20% set-up allowance (min)

Time for cutting tube estimated at 5 min (SAE) see Dwg FFS-211

Costing Tender

-

MIG/TIG welder

Formula Ford SpiritPart

Sub Assembly

Cut 2 tubes to a length of 280mm, with both ends chamfered to 45°

band saw

Part No Unit Price (/m) No requ'd Delivery Total Cost£2,65/m 210mm - £0,56

Op No Mach/dept Time (min) Cost10 3 £1,75

£0,30

20 3 £1,75£0,30

6 -1,2

Total estimated time (min) 7,2

£0,56£35/h £4,20£6/h £0,72

£5,48

Op 10:Op 20:

Signed Date

20% set-up allowance (min)

TOTAL

Formula Ford Spirit

Bill Of Material

Description

Part

Total £ Labour

Costing Tender

Operation

Team Spirit 19.3.07

Cut 2 tubes to a length of 103mm, with an angle of 6° as shown in Dwg FFS-221

Band Saw -

Lime / angle grinder: grinding disc

Tools required

Addition of Time (min)

Time for de-burring estimated at 3min (SAE)Time for cutting estimated at 3min (SAE) see Dwg FFS-221

Comments

Total Raw Materials

Total £ Machine

angle grinder

de-burr end of tubes using angle grinder

Bulkhead Sheet 1/1Bottom Tubes Part n° FFS-221

Mild steel tube (25x25x2)

Sub Assembly

Part No Unit Price (/m) No requ'd Delivery Total Cost£2,65/m 90mm - £0,24

Op No Mach/dept Time (min) Cost10 3 £1,75

£0,30

20 3 £1,75£0,30

6 -1,2

Total estimated time (min) 7,2

£0,24£35/h £4,20£6/h £0,72

£5,16

Op 10:Op 20:

Signed Date

de-burr end of tubes using angle grinder

Bulkhead Sheet 1/1Top Tubes Part n° FFS-222

Mild steel tube (25x25x2)

Sub Assembly

Addition of Time (min)

Time for de-burring estimated at 3min (SAE)Time for cutting estimated at 3min (SAE) see Dwg FFS-222

Comments

Total Raw Materials

Total £ Machine

angle grinder

Operation

Team Spirit 19.3.07

Cut 2 tubes to a length of 43mm, with an angle of 6° as shown in Dwg FFS-222

Band Saw -

Lime / angle grinder: grinding disc

Tools required

20% set-up allowance (min)

TOTAL

Formula Ford Spirit

Bill Of Material

Description

Part

Total £ Labour

Costing Tender

Part No Unit Price No requ'd Delivery Total Cost£2,65/m 200mm - £0,53

Op No Mach/dept Time (min) Cost10 3 £1,75

£0,30

20 2 £1,17£0,20

5 -1

Total estimated time (min) 6

£0,53£35/h £3,50£6/h £0,60

£4,63

Op 20:Op 30:

Signed Date

-

Lime / angle grinder: grinding disc

Bulkhead Sheet 1/1Internal R Triangles Part n° FFS-231

Time for cutting estimated at 3min (SAE) see Dwg FFS-231Comments

Tools required

de-burr tubes all around using angle grinder

angle grinder

OperationCut tube to 4 lengths of 48,5mm, with 48° angles on both ends as shown in Dwg FFS-231

Band Saw

Formula Ford Spirit

Mild steel tube (25x25x2)

Team Spirit 19.3.07

Sub Assembly

Costing Tender

Part

Time for de-burring estimated at 2min (SAE)

Bill Of Material

Description

Addition of Time (min)

Total Raw MaterialsTotal £ LabourTotal £ Machine

20% set-up allowance (min)

TOTAL

Part No Unit Price No requ'd Delivery Total Cost£2,65/m 200mm - £0,53

Op No Mach/dept Time (min) Cost10 3 £1,75

£0,30

20 2 £1,17£0,20

5 -1

Total estimated time (min) 6

£0,53£35/h £3,50£6/h £0,60

£4,63

Op 20:Op 30:

Signed Date

Bill Of Material

Description

Addition of Time (min)

Total Raw MaterialsTotal £ LabourTotal £ Machine

20% set-up allowance (min)

TOTAL

Formula Ford Spirit

Mild steel tube (25x25x2)

Team Spirit 19.3.07

Sub Assembly

Costing Tender

Part

Time for de-burring estimated at 2min (SAE) see Dwg FFS-232Time for cutting estimated at 3min (SAE) see Dwg FFS-232

Comments

Tools required

de-burr tubes all around using angle grinder

angle grinder

OperationCut tube to 4 lengths of 44mm, with both 45° angles on both ends as shown in Dwg FFS-232

Band Saw -

Lime / angle grinder: grinding disc

Bulkhead Sheet 1/1Lateral R Triangles Part n° FFS-232

Part No Unit Price No requ'd Delivery Total Cost£20,68/m² 0,056m² - £1,16

Op No Mach/dept Time (min) Cost10 3 £1,75

£0,3020 5 £2,92

£0,5030 3 £1,75

£0,30

11 -2,2

Total estimated time (min) 13,2

£1,16£35/h £7,70£6/h £1,32

£10,18

Op 10:Op 20:Op 30:

Signed Date

Front Plate Part n° FFS-24

Costing Tender

Part Bulkhead Sheet 1/1

Formula Ford Spirit

Sub Assembly

Bill Of Material

Descriptionmild steel plate 280mmx200mmx2mm

Tools requiredOperation

Group D 19.3.07

Time for chamfering estimated at 3min (SAE)

Lime / angle grinder: grinding disc / de-burring tool

Addition of Time (min)

Total Raw Materials

Cut out plate 280x196,5x3mm as shown on Dwg FFS-24

Cutting saw-

Time for drilling estimated at 5min (SAE) see Dwg FFS-24

de-burr holes and outline plate using angle grinder and de-burring tool

angle grinder

Drill 10 holes of 8mm dia in plate as shown in Dwg

Pillar drill Pillar drill, drill 8mm dia

20% set-up allowance (min)

TOTAL

Time for cutting plate estimated at 3min (SAE) see Dwg FFS-24Comments

Total £ LabourTotal £ Machine

Part No Unit Price No requ'd Delivery Total Cost£20,68/m² 0,0075m² £0,15

Op No Mach/dept Time (min) Cost10 5 £2,92

£0,5020 3 £1,75

£0,308 -

1,6Total estimated time (min) 9,6

£0,15£35/h £5,60£6/h £0,96

£6,71

Op 10:Op 20:

Signed Date

Bulkhead Sheet 1/1Reinforcement Plates Part n° FFS-25

Operation

Lime / angle grinder: grinding disc

Total £ Machine

Total Raw MaterialsTotal £ Labour

de-burr outline plates using angle grinder

angle grinder

20% set-up allowance (min)

TOTAL

Part

Time for chamfering estimated at 3 min (SAE) see Dwg FFS-25Time for cutting plate estimated at 5 min (SAE) see Dwg FFS-25

Comments

Tools required

mild steel plate 300mmx25mx2mm

Sub Assembly

Addition of Time (min)

Group D 19.3.07

Costing Tender

Cut out 2 plates 146,5x25x3mm as shown on Dwg FFS-25

Cutting saw-

Formula Ford Spirit

Bill Of Material

Description

Part No Unit Price No requ'd Delivery Total Cost£20,68/m² 0,0062m² - £0,13

Op No Mach/dept Time (min) Cost20 3 £1,75

£0,3030 2 £1,17

£0,2040 2,5 £1,46

£0,2550 3 £1,75

£0,3010,5 -2,1

Total estimated time (min) 12,6

£0,13£35/h £7,35£6/h £1,26

£8,74

Op 20:Op 30:Op 40:Op 50:

Signed Date

Formula Ford Spirit

Sub Assembly

Costing Tender

angle grinder

Bulkhead Sheet 1/1Brackets Part n°

Bill Of Material

PartFFS-26

Group D 19.3.07

Descriptionmild steel plate 310mmx20mmx3mm

Time estimated for chamfering at 3min (SAE) see Dwg FFS-26Time for cutting estimated at 2,5min (SAE) see Dwg FFS-26Time for chamfering estimated at 2min (SAE) see Dwg FFS-26Time for Pillar drill estimated at 3min (SAE) see Dwg FFS-26

Comments

Chamfer edges on plates

circle Saw-

Lime / angle grinder: grinding disc

Cut plate to pieces of 60x20x3mm (5 cuts)

Chamfer holes on both sides using de-burring tool

pillar drillde-burring tool

Drill 6x7mm holes in the plate as shown on Dwg FFS-26

pillar drill7mm drill

Operation Tools required

20% set-up allowance (min)

TOTAL

Addition of Time (min)

Total Raw MaterialsTotal £ LabourTotal £ Machine

Part No Unit Price No requ'd Delivery Total Cost£20,68/m² 0,0118m² - £0,24

Op No Mach/dept Time (min) Cost10 3 £1,75

£0,3020 4 £2,33

£0,4030 2 £1,17

£0,20

9 -1,8

Total estimated time (min) 10,8

£0,24£35/h £6,30£6/h £1,08

£7,62

Op 10:Op 20:Op 30:

Signed Date

Total £ LabourTotal £ Machine

TOTAL

Time for cutting plate estimated at 3min (SAE) see Dwg FFS-27Comments

Time for drilling estimated at 4min (SAE) see Dwg FFS-27

de-burr holes and outline plate using angle grinder and de-burring tool

angle grinder

Drill 3 holes of 8mm dia in each plate as shown in Dwg FFS-27

Pillar drill Pillar drill, drill 8mm dia

Lime / angle grinder: grinding disc / de-burring tool

Addition of Time (min)

Total Raw Materials

Cut out 2 plates of 196,5mm long and 30mm wide as shown in Dwg FFS-27

Cutting saw -

20% set-up allowance (min)

Group D 19.3.07

Time for chamfering estimated at 2min (SAE) see Dwg FFS-27

Bill Of Material

Descriptionmild steel plate 393mmx30mmx1mm

Tools requiredOperation

Side Fence Part n° FFS-27

Costing Tender

Part Bulkhead Sheet 1/1

Formula Ford Spirit

Sub Assembly

Part No Unit Price No requ'd Delivery Total Cost£20,68/m² 0,017m² - £0,35

Op No Mach/dept Time (min) Cost10 3 £1,75

£0,3020 4 £2,33

£0,4030 2 £1,17

£0,20

9 -1,8

Total estimated time (min) 10,8

£0,35£35/h £6,30£6/h £1,08

£7,73

Op 10:Op 20:Op 30:

Signed Date

Top Fence Part n° FFS-28

Costing Tender

Part Bulkhead Sheet 1/1

Formula Ford Spirit

Sub Assembly

Descriptionmild steel plate 560mmx30mmx1mm

Tools requiredOperation

Group D 19.3.07

Time for chamfering estimated at 3min (SAE) see Dwg FFS-28

Addition of Time (min)

Total Raw Materials

Cut out 2 plates of 280mm long and 30mm wide as shown in Dwg FFS-28

Cutting saw -

20% set-up allowance (min)

de-burr holes and outline plate using angle grinder and de-burring tool

angle grinder

Drill 2 holes of 8mm dia in each plate as shown in Dwg FFS-28

Pillar drill Pillar drill, drill 8mm dia

Lime / angle grinder: grinding disc / de-burring tool

Bill Of Material

Time for cutting plate estimated at 3min (SAE) see Dwg FFS-28Comments

Time for drilling estimated at 5min (SAE) see Dwg FFS-28

Total £ LabourTotal £ Machine

TOTAL

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FFS-21

FFS-25

196,50

171,50

FFS-26

FFS-221

FFS-222

FFS-24

FFS-232

280

2103

43

300

288

95,55°

17

30

FFS-231

FFS-27

FFS-28

D

E

F

C

1 2 3 4

B

A

321 5

C

D

4 6 7 8

A

B

2nd Bulkhead

WEIGHT:

A3

SHEET 1 OF 1SCALE:1:3

DWG NO.

TITLE:

REVISIONDO NOT SCALE DRAWING

MATERIAL:

DATESIGNATURENAME

DEBUR AND

BREAK SHARP

EDGES

FINISH:UNLESS OTHERWISE SPECIFIED:

DIMENSIONS ARE IN MILLIMETERS

SURFACE FINISH:

TOLERANCES:

LINEAR:

ANGULAR:

Q.A

MFG

APPV'D

CHK'D

DRAWN

FFS-20

Spirit Racing Cars

196,50

280

45°

FFS-211

FFS-212

FFS-211

FFS-212

2

FFS-24

B

C

D

1 2

A

321 4

B

A

5 6

DRAWN

CHK'D

APPV'D

MFG

Q.A

UNLESS OTHERWISE SPECIFIED:

DIMENSIONS ARE IN MILLIMETERS

SURFACE FINISH:

TOLERANCES:

LINEAR:

ANGULAR:

FINISH: DEBUR AND

BREAK SHARP

EDGES

NAME SIGNATURE DATE

MATERIAL:

DO NOT SCALE DRAWING REVISION

TITLE:

DWG NO.

SCALE:1:5 SHEET 1 OF 1

A4

C

WEIGHT:

Frame

FFS-21

Spirit Racing Cars

Steel

45°

280

Tube thickness: 2mm

B

C

D

1 2

A

321 4

B

A

5 6

DRAWN

CHK'D

APPV'D

MFG

Q.A

UNLESS OTHERWISE SPECIFIED:

DIMENSIONS ARE IN MILLIMETERS

SURFACE FINISH:

TOLERANCES:

LINEAR:

ANGULAR:

FINISH: DEBUR AND

BREAK SHARP

EDGES

NAME SIGNATURE DATE

MATERIAL:

DO NOT SCALE DRAWING REVISION

TITLE:

DWG NO.

SCALE:1:5 SHEET 1 OF 1

A4

C

WEIGHT:

Frame top tube

FFS-21125CD4

Spirit Racing Cars

45°

196,50

Tube thickness: 2mm

B

C

D

1 2

A

321 4

B

A

5 6

DRAWN

CHK'D

APPV'D

MFG

Q.A

UNLESS OTHERWISE SPECIFIED:

DIMENSIONS ARE IN MILLIMETERS

SURFACE FINISH:

TOLERANCES:

LINEAR:

ANGULAR:

FINISH: DEBUR AND

BREAK SHARP

EDGES

NAME SIGNATURE DATE

MATERIAL:

DO NOT SCALE DRAWING REVISION

TITLE:

DWG NO.

SCALE:1:5 SHEET 1 OF 1

A4

C

WEIGHT:

Frame side tube

FFS-21225CD4

Spirit Racing Cars

6°

103

Tube thickness: 2mm

B

C

D

1 2

A

321 4

B

A

5 6

DRAWN

CHK'D

APPV'D

MFG

Q.A

UNLESS OTHERWISE SPECIFIED:

DIMENSIONS ARE IN MILLIMETERS

SURFACE FINISH:

TOLERANCES:

LINEAR:

ANGULAR:

FINISH: DEBUR AND

BREAK SHARP

EDGES

NAME SIGNATURE DATE

MATERIAL:

DO NOT SCALE DRAWING REVISION

TITLE:

DWG NO.

SCALE:2:1 SHEET 1 OF 1

A4

C

WEIGHT:

Bottom side tube

FFS-22125CD4

Spirit Racing Cars

43

6°

Tube thickness: 2mm

B

C

D

1 2

A

321 4

B

A

5 6

DRAWN

CHK'D

APPV'D

MFG

Q.A

UNLESS OTHERWISE SPECIFIED:

DIMENSIONS ARE IN MILLIMETERS

SURFACE FINISH:

TOLERANCES:

LINEAR:

ANGULAR:

FINISH: DEBUR AND

BREAK SHARP

EDGES

NAME SIGNATURE DATE

MATERIAL:

DO NOT SCALE DRAWING REVISION

TITLE:

DWG NO.

SCALE:2:1 SHEET 1 OF 1

A4

C

WEIGHT:

Top side tube

FFS-22225CD4

Spirit Racing Cars

22

48,5

48°

48°

2

25

C

2 31 4

B

A

D

E

F

Internal reinforcement triangles

WEIGHT:

A4

SHEET 1 OF 1SCALE:1:1

DWG NO.

TITLE:

REVISIONDO NOT SCALE DRAWING

MATERIAL:

DATESIGNATURENAME

DEBUR AND

BREAK SHARP

EDGES

FINISH:UNLESS OTHERWISE SPECIFIED:

DIMENSIONS ARE IN MILLIMETERS

SURFACE FINISH:

TOLERANCES:

LINEAR:

ANGULAR:

Q.A

MFG

APPV'D

CHK'D

DRAWN

FFS-23125CD4

Spirit Racing Cars

22

44

45°

45°

25

2

C

2 31 4

B

A

D

E

F

Lateral reinforcement triangles

WEIGHT:

A4

SHEET 1 OF 1SCALE:2:1

DWG NO.

TITLE:

REVISIONDO NOT SCALE DRAWING

MATERIAL:

DATESIGNATURENAME

DEBUR AND

BREAK SHARP

EDGES

FINISH:UNLESS OTHERWISE SPECIFIED:

DIMENSIONS ARE IN MILLIMETERS

SURFACE FINISH:

TOLERANCES:

LINEAR:

ANGULAR:

Q.A

MFG

APPV'D

CHK'D

DRAWN

FFS-23225CD4

Spirit Racing Cars

196,50

280

Thickness: 2mm

B

C

D

1 2

A

321 4

B

A

5 6

DRAWN

CHK'D

APPV'D

MFG

Q.A

UNLESS OTHERWISE SPECIFIED:

DIMENSIONS ARE IN MILLIMETERS

SURFACE FINISH:

TOLERANCES:

LINEAR:

ANGULAR:

FINISH: DEBUR AND

BREAK SHARP

EDGES

NAME SIGNATURE DATE

MATERIAL:

DO NOT SCALE DRAWING REVISION

TITLE:

DWG NO.

SCALE:1:5 SHEET 1 OF 1

A4

C

WEIGHT:

Front Plate

FFS-24mild-steel

Spirit Racing Cars

25

146,50

thickness: 2mm

B

C

D

1 2

A

321 4

B

A

5 6

DRAWN

CHK'D

APPV'D

MFG

Q.A

UNLESS OTHERWISE SPECIFIED:

DIMENSIONS ARE IN MILLIMETERS

SURFACE FINISH:

TOLERANCES:

LINEAR:

ANGULAR:

FINISH: DEBUR AND

BREAK SHARP

EDGES

NAME SIGNATURE DATE

MATERIAL:

DO NOT SCALE DRAWING REVISION

TITLE:

DWG NO.

SCALE:1:5 SHEET 1 OF 1

A4

C

WEIGHT:

Reinforcement plate

FFS-25mild steel

Spirit Racing Cars

36°

20

R10

7

40 12,50

B

C

D

1 2

A

321 4

B

A

5 6

DRAWN

CHK'D

APPV'D

MFG

Q.A

UNLESS OTHERWISE SPECIFIED:

DIMENSIONS ARE IN MILLIMETERS

SURFACE FINISH:

TOLERANCES:

LINEAR:

ANGULAR:

FINISH: DEBUR AND

BREAK SHARP

EDGES

NAME SIGNATURE DATE

MATERIAL:

DO NOT SCALE DRAWING REVISION

TITLE:

DWG NO.

SCALE:2:1 SHEET 1 OF 1

A4

C

WEIGHT:

Attachment bracket

FFS-26mild steel

Spirit Racing Cars

196,50

30

thickness: 1mm

B

C

D

1 2

A

321 4

B

A

5 6

DRAWN

CHK'D

APPV'D

MFG

Q.A

UNLESS OTHERWISE SPECIFIED:

DIMENSIONS ARE IN MILLIMETERS

SURFACE FINISH:

TOLERANCES:

LINEAR:

ANGULAR:

FINISH: DEBUR AND

BREAK SHARP

EDGES

NAME SIGNATURE DATE

MATERIAL:

DO NOT SCALE DRAWING REVISION

TITLE:

DWG NO.

SCALE:1:5 SHEET 1 OF 1

A4

C

WEIGHT:

Side fence

FFS-27mild steel

Spirit Racing Cars

28030

thickness: 1mm

B

C

D

1 2

A

321 4

B

A

5 6

DRAWN

CHK'D

APPV'D

MFG

Q.A

UNLESS OTHERWISE SPECIFIED:

DIMENSIONS ARE IN MILLIMETERS

SURFACE FINISH:

TOLERANCES:

LINEAR:

ANGULAR:

FINISH: DEBUR AND

BREAK SHARP

EDGES

NAME SIGNATURE DATE

MATERIAL:

DO NOT SCALE DRAWING REVISION

TITLE:

DWG NO.

SCALE:1:5 SHEET 1 OF 1

A4

C

WEIGHT:

Top fence

FFS-28mild steel

Spirit Racing Cars

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