für die zukunft junger ingenieure chassis design space frame 2009 ronald müller...
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Für die Zukunft junger Ingenieure
Chassis Design Space Frame
2009
Ronald MüllerGesamtfahrzeugleiterRennteam Uni Stuttgart
Für die Zukunft junger Ingenieure
Basics Rules and Rule Changes Concept Design Manufacturing
Table of Contents
Für die Zukunft junger Ingenieure
What is the frame? Connects all parts of the car
Accommodates the driver
What are the requirements? Needs to be lightweight and stiff
Easy to manufacture
Low in cost
Basics
Für die Zukunft junger Ingenieure
Why a space frame? Ideal for first year teams
Load paths are easy to spot
Manufacturing facilities are easy to find
Material is cheap
Basics
Für die Zukunft junger Ingenieure
NOW YOU KNOW:
The frame connects all parts of the car.
It defines - together with the seat - the ergonomics of the driver
It needs to be stiff and lightweight
And the good news is:
There is help! So you don't have to start from scratch:
THE RULES!
Rules & Rule Changes
Für die Zukunft junger Ingenieure
The Rules define the most important tubes:
Steel tubing for front and main roll hoops
Main and front hoop bracing
Side impact structure
These make up the backbone of the front and middle of the frame.
New this year:
They also define the dimensions of the cockpit:
THE TEMPLATES
Rules & Rule Changes
Für die Zukunft junger Ingenieure
Formula One TemplatesRules & Rule Changes
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4.1 Cockpit Opening
4.1.1 In order to ensure that the opening giving access to the cockpit is of adequate size, a template shown in Figure 8 will be inserted into the cockpit opening. It will be held horizontally and inserted vertically until it has passed below the top bar of the Side Impact Structure (or until it is 350 mm above the ground for monocoque cars).
4.1.2 During this test, the steering wheel, steering column, seat and all padding may be removed.
Rules & Rule Changes
Für die Zukunft junger Ingenieure
Rules & Rule Changes 4.1 Cockpit Opening - Dimensions
Für die Zukunft junger Ingenieure
4.2 Cockpit Internal Cross Section:
4.2.1 A free vertical cross section, which allows the template shown in Figure 9 to be passed horizontally through the cockpit to a point 100 mm (4 inches) rearwards of the face of the rearmost pedal when in the inoperative position, must be maintained over its entire length.
4.2.2 The only things that may encroach on this area are the steering wheel, steering column and any padding that is required by Rule 5.7 “Driver’s Leg Protection”.
4.2.3 For 2009, teams whose cars do not comply with 4.1 or 4.2 will have 35 points deducted from their Design Event score.
Rules & Rule Changes
Für die Zukunft junger Ingenieure
Rules & Rule Changes 4.1 Cockpit Internal Cross Section - Dimensions
Für die Zukunft junger Ingenieure
NOW YOU KNOW:
You know the basics and the rules to obey
Many tube dimensions and positions are given
The size of the drivers compartment is defined by the templates
Now let's have a closer look at one possibility for designing your space frame.
Rules & Rule Changes
Für die Zukunft junger Ingenieure
Time Schedule
Mockup
Improve CAD-Model
&Suspension
Load Cases&
Simple FEA
CONCEPT DESIGN MANUFACTURING
Improve CAD-Model
&Suspension
First CAD-Model
Coordinating/Modification of CAD, Suspension & Mockup
Improve CAD-Model
&Suspension
Detailed FEA
OrderMaterial!
READ THERULES!
Tires&
Suspension
Assembly of the car cannot start until
the frame is finished!
Für die Zukunft junger Ingenieure
Ergonomic Research
Get measurements of potential drivers in the team
First draft of driver position, with engine and wheelbase (location of the tires) in place
Concept
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First CAD-Model CAD-Model considering rules and available space
Make yourself placeholders to clarify the design envelope
Concept
Für die Zukunft junger Ingenieure
Mockup: Aim: define the major dimensions of the
frame
Build the first mockup as soon as possible
Make yourself hardcopies of the templates and Percy
Put the improvements back in CAD
Interfaces with the suspension team
Concept
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Mockup:Concept
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Load cases & Simple FEA Breaking, Acceleration, Cornering
Beam/Truss Model
→ Best way to optimize weight & stiffness
Concept & Design
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Use triangulations to avoid squares
Design
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Load initiation in nodes to prevent bending
Design
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Design
OD ID WT I CS
12 10 1 527 34,558
12,7 10,9 0,9 578,46 32,987
Try to use big outer diameters and thin wall thickness (min. for welding 0.8mm)
+10% bending stiffness
-5% weight
Für die Zukunft junger Ingenieure
Design
OD ID WT I CS
25 20 2,5 11320,78 176,72
25,4 20,6 2,4 11591,99 173,42
30 26 2 17329,03 175,93
Try to get as close to the minimum requirements as possible
You cannot reduce weight as CS is prescribed
Think about imperial tube sizes
+53% bending stiffness
e.g.: Mainhoop: Wall thickness ≥ 2mm
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Try to lay the dampers parallel to tubes
Design
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Material Stiffness cannot be improved by using alloyed steel!
Still it might be sensible to use alloyed steel for security relevant structures (cockpit, suspension)
Heat treatment:
It is definitively better to do it (Design)
Do it locally to prevent huge distortion
Welding
TIG!
Bending
Use heat treated tubes for bending
Design
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Design
St37(1.0116)
25CrMo4(1.7218)
15CDV6(1.7765)
Price +++ + -
Welding
+ ++ +++
Safety
o ++ +++
Choice
+ ++ +
Material
Wishbones, Suspension
Front Vehicle, Cockpit
Für die Zukunft junger Ingenieure
Order tubes early
Laser cut the ends or grind with paper shape
Manufacturing
Für die Zukunft junger Ingenieure
Take your time to adjust the tubes properly before welding
Manufacturing
Für die Zukunft junger Ingenieure
05. – 09. August 2009
See you in Hockenheim 2009