final report(final version)

8/2/2019 Final Report(Final Version)

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______________________________________________ ME3901 Project-Design Realization_

Department of Mechanical engineering

ME3901 Project Design Realization

Design Improvement of Goods Trolley

Final Report

Group No. 5

Group Name KTB

Group Members

Student ID Name Project Role

10945826T Li Ka Kin Project Manager

10947936T Chow Chi Hin Design Manager

10951673T Yu Sin Him Design Manager

10953120T Wong Tsz Yu Marketing Manager


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2Li Ka Kin, Chow Chi Hin, Yu Siu Him, Wong Tsz Yu

Abstract

Our group found that when we were using trolley to deliver the goods,

the whole trolley was oscillated during move and it made the goods

move on the platform even dropping down. Thus, this report shows

how to build a product to minimizing the vibration problem of a goods

trolley in our project. In our consideration, vibration is also the

parameter of producing other badly mechanical issues such as

excessive wear, fatigue failure, damage to structure, etc. Therefore,

we design anti-vibrators not only reduce vibration level but slow the

mechanical issues occur. For supporting our design can improve the

vibration problem, two vibration tests are held, one is for prototype

and other one is for design product, and those are conducted under

the same conditions. After the comparisons of the data which collect

from the two tests, we find that the anti-vibrators have actually

absorbed the part of vibration force during the movement of the goods

trolley. Especially, it obviously has a better performance during

moving in on-load condition. In addition, the practical experiment tests

the durability of anti-vibrators which withstood the vibration force and

ensure no components loosening during move.


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Acknowledgement

Dr. Udaya Kahangamage (The Lecturer of Project -

Design Realization)

Chan Yu-Ming (TA)

Dr. X J Jing (The Lecturer of Dynamics and Vibration)


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Table of Content

Chapter 1 Introduction

Chapter 2 Methodology

Chapter 3 Initial product analysis

Chapter 4 Building & improvements theconceptual design

4.1 Components

4.2 Production Process4.3 Modifying the design product

Chapter 5 Detail description of the vibration test

5.1 Instruments5.2 Test5.3 Data

5.4 Factor affecting the result

Chapter 6 Data analysis & Findings

Chapter 7 Conclusion

Chapter 8 Reflection on the learning experience

Reference

Appendix:

(a) Project Management(b) Manpower Management(c) Financial Management


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Chapter 1 Introduction

The aim of this final report is to describe and illustrate in detail about

the design problems, the data analysis, test and improvement which

were the experiments in our project.

First, our Group KTB is to design the anti-vibrator for minimizing the

vibration level between the wheels and the rough road during the

movement of a goods trolley. Before we decided to use now design to

become true, we had to consider and analyze which designs were

satisfied with easy for assembly and disassembly four anti-vibrators,

material requirements, replaceable or easy maintenance and also did

not over the budget, etc.

Second, after carried out the material selection, we started to

purchase the required components and applicable tools for making the

anti-vibrators (IBI manufacture) and installation.

Third, we started to measure and mark out the location for the

installation of anti-vibrators. Because the anti- vibrators needed to

compress for vibration isolation, we must remove the bracket whichwas bonded with wheels axles and the platform for allow mounting

anti vibrators between them. Then, we drilled the holes on the

wheels axles and the platform and mounted thread bolts on the

platform which was used to increase the intervals for putting the anti

vibrators on it. Finally, we installed the wheels axles and wheels and

were locked by fasteners.

(The details of assembly are illustrated in Chapter 4)

Forth, we were conducting the second vibration tests as same as the

first test for prototype with on-load and no load separately. Next, we

compared the data between the design product and prototype and

checked whether it was better than before and also the magnitude of

the improvement (reduced vibration level).


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In addition, during the installation of anti-vibrators, we found that two

problems were existed in our design and listed below:

1) The friction blocked the movement between thread bolts and the

holes. It caused the anti vibrator could not move so lost its

function. So we had to enclose part of the threads which may be

contacting with the holes by plastic tube and enlarge the holes for

allowing the thread bolts to pass through smoothly.

2) The four wheels were swaying during move as the thread bolts

could not be locked securely. We had to lock the each thread bolts

in the platform by two nuts to prohibit from sway.

During the vibration test, two problems were occurred in our design

and listed below:

1)The bottom nut which was mounting the anti-vibrator and the

wheels axle loosed during move on the rough floor. For prevent the

whole assembly to loose, we had dropped some screw glue

between thread bolts and nuts.

2)The wheels level was not aligned that only three or two wheels

could touch the ground during move or rest. We had to readjust

the height (stiffness) of anti vibratorsto align the level.

Finally, we did a practical experiment about conveyance of goods on a

general pedestrian road. The purpose of the experiment was testing

its durability and ensuring no iteration or other problems would be

occurred for affecting the safety. The aspect of design product was

almost completed.

The detail of test results, finding and conclusion are showed on the

following chapter.


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Chapter 2: Methodology

Prototype finding (After the vibration test)

Excessive vibration during moving on the rough road

The level of trolley wheels are not align

Implementation:1. Research and design a product to improve the problems

2. Use software to simulate our design product in the visual situation

Analysis

Problem Identification

Vibration affect the stability of the trolley

Balance affect the controllabilit of the trolle

Conceptualization

Design Feasibility

Implementation:

3. Material selection

4. Follow the layout to build the product

5. Conduct a vibration test for the design product

6. Collect and compare the data

Modification

Problems & Solutions:

a) Problem: Stability of the trolleySolution: Adjust the same height (stiffness) of antivibrators

b) Problem: Friction between holes and thread boltSolution: Put the plastic tubes outside the thread bolts and file the burrs onthe holes.

b) Problem: Nuts loosen during operationSolution: Use the thread locker glue or thread adhesive tape

Finding


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Testing: Vibration test

1. First Vibration test for design product2. Take data of loading & unloading

3.Key issues & Problems

3.1 Nuts loosen during movement

3.2 4-wheels unbalance

3.3 Friction produced between holes and thread bolt

4. Second Vibration test for modified product5. Take data of loading & unloading6. Compare the vibration level with whether add loading or

not after modification

7. Compare the vibration level difference between originaland modifiable one

8. Practical experiment for modified product9. Comment by the customer10.Summary : comments, data and problems & solutions

Calculation:

1. Vibration level

2. Average vibration level

3. Accuracy

Documentation:

Prepare the final report for the design

product


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On load /unload

Chapter 3: Initial product analysis:

Problem Identification

Vibration level affect the stability of trolley The relationship between vibration and loading weight

The relationship between vibration and operation speed

Balance of trolley

The friction of between rotating and stationary machinecomponents (shaft and wheels)

Environmental condition

Vibration can be defined as the cyclic or oscillating motion of a

product or component from its position of rest. It can cause damage to

structures and machine assemblies, resulting in operation, excessive

wear, or even fatigue failure For initial trolley, we found that many

parameters (above table) affect the vibration level of it. In this project,

we concerned and identified four main parameters which affect the

vibration level obviously.

Balancing

Parameters Operation

speed

Environmental

condition


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Balancing:

Unbalance is defined as an exciting force. The exciting force is trying

to cause vibration. In this case, we found that the wheels level was not

aligned that only three or two wheels could touch the ground. We need

to minimize the vibration by readjusting the height after modification.

Mass of the vibrating system:

We knew that mass (loading) is trying to oppose the exciting force and

control or minimize the vibration. So, our prediction is that the

oscillation in on-load test must be lower than the unload one. After

the test, we want to compare the vibration different against the unload

one and prove our assumption right through the result.

Operation speed:

When the operation speed is high

than the critical speed, the

vibration level will be lower at the

same time (refer to F.g3.1 chart).

Obviously, operation speed is theimportant part in vibration. In

following part, we will process the

vibration test in several speeds

and analyze the data different.

(F.g3.1)

Environmental condition:

Ground situation is also a main environmental condition in this project.

We decided to test the trolley on different ground condition and

thereby proved that ground condition had a great effect of vibration.


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Chapter 4: Building & improvements the conceptual

design

In this chapter, we would like to illustrate how to develop our

conceptual design and how to solve the design problems which isfound in the vibration test.

Initially, we would like to introduce the components which we had

used.

4 Thread bolts

4 Springs

Fasteners


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Production Process:

Step 1: Dismantling the 4 wheels and 2 wheels axles

(a) Disassembling the wheels (b) The wheels axles with brackets


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(c) Using a hand bow saw to disassemble the wheels axles with brackets

Step 2: Drilling the holes on the wheels axles and platform. Thosediameters of holes are 10 mm bigger than the diameters of thread bolts.

Dismantled

Mark out the drilling

location


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(d) Drilling the holes on the wheels axles by the portable electric drill

(e) Drilling the holes on the platform


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Step 3: Assemble all the components on the trolley.

(f) Using the fasteners to lock the thread bolts on the platform


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Modifying the design product:

(a)Put the plastic tube outside the thread bolts to minimize the

friction produced between the holes of wheel axles, and alsoprevent the components for wearing.

(b)Using the fasteners to lock the assembly on the wheels axles


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After the vibration test, we found that the fasteners would be loosened

during moving on a rough road.

(c) P.T.F.E thread seal tape wrap was used to prohibit the fasteners

loosening.

(d) Readjusting the height of anti-vibrators to align the wheels level


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Chapter 5: Detail description of the vibration test

We decide an experiment to test the vibration level of the trolley. In

our experiment, we measure the damping ratio by the signal analyzer

to isolate a single mode from the frequency response function. We testthe trolley on the rough path (Fig.5.4) with different load add on it (Fig

5.5 & Fig 5.6).

(a)Instrument

The Dual-Channel Signal Analyzers type 2032(Fig.5.1) is the instrument

to determine the modal parameters of simple structures. The model

frequencies are determined from the frequency response function. The model

damping is found from the decay rate, measured from the magnitude of the

impulse response function, which is produced by isolating a single mode from

the frequency weighting function. The charge amplifier (Fig.5.2) use to

transfers the input charge to another reference capacitor and produces an

output voltage equal to the voltage across the reference capacitor. The

accelerometer (Fig.5.3) is a device that measures proper acceleration.

Dual channel signal analyzer type 2032

Fig.5.1


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Charge amplifier

Accelerometer

Fig.5.2

Fig.5.3


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(b)Testing

We divide the experiment into two parts, no-load test & on-loadtest. We use same instrument and load to test the trolley beforeand after modification.

1. First test (before modification)Put the trolley on the rough path and pull it in a constant acceleration

10 kg add on the trolley for the test

20 kg add on the trolley for the test

Fig.5.4

Fig.5.5

Fig.5.6


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The value of Y is more negative, the less oscillation of

the trolley is presented.

Record the Y (-19.5dB)with fixed frequency bandwidth X

in different test

Fig.5.7

Fig.5.8


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2. Second test (after modification)Trolley after modification

Test without loading

10kg load add on the trolley

20kg load add on the trolley

Fig.5.9

Fig.5.10

Fig.5.11

Fig.5.12


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Data

X is the frequency bandwidth = 117.0Hz

1. Before modification,

1

st

test

2

nd

test

3

rd

test

4

th

test

Loading(kg) Vibration level Y (db)

0 -19.5 -17.9 -19.3 -20.1

10 -22.5 -21.8 -22.1 -24.0

20 -30.9 -29.0 -32.2 -30.9

2.After modification,1st

test

2nd

test

3rd

test

4th

test


0 -27.6 -22.6 -24.3 -25.4

10 -33.2 -33.3 -31.8 -32.5

20 -41.3 -43.2 -39.7 -41.1

To calculation the mean value ]101

log[101

10

N

i

Li

pN

L where Li = average of the dB

Before After

Loading(kg) Mean (db)

0 -24.6

10 -32.7

20 -41.2

Loading(kg) Mean (db)

0 -19.1

10 -22.5

20 -30.6


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(d)Factors affecting the result

Factor:

1. Uneven velocity of the trolley during the test

2. level of 4-wheels unbalances

3. Friction produced between holes and thread bolt

Remedial actions taken:

1. To get the accuracy data, we try to pull the trolley with a

constant acceleration. We also do the test 4 times to reduce the

error.

2. To keep to the trolley in a balance level, we adjust the nut to

balancing the trolley. We use the level bar to balance the 4-

wheels.

The friction produce between the holes and the thread bolt will affectthe vibration level. To improve this, we try to use the plastic tube to

cover it, as the result to reduce the friction between them.


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Practical experiment:

The main objective of our project is decreasing the vibration and norisk for human use. So, we need to provide a final practical experimentto test the trolley is functional and safety.

In experiment process, we decided to test the structure of sub-assemblies whether firm or not first. Base on previous experience, thesub- assemblies will be possible to loosen during operation. Weexpected the sub- assemblies will not be loosen and raise the reliabilityof product.

During experiment process, we trial use to keep the trolley in motionin 30 minutes continuously. After 30 minutes movement, the trolleycan still function normally and all parts are firmly.

Rough condition Smooth condition

In second part of practical experiment, each group-mate will try to pull

the trolley individually on several ground condition and make a

comment.


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Chapter 6: Dataanalysis & findingsVibration may be characterized by:

(i) The frequency in Hz;

(ii) The amplitude of the measured parameter, which may be

displacement, velocity, or acceleration. This is normally referred to as

the vibration amplitude when expressed in units, but vibration level

when expressed in decibels.

Thus if the measured amplitude is A1 and the reference amplitude is A0,

the vibration level expressed in decibels is:

1. From the data of first test,

Before

modify

1st

test

2nd

test

3rd

test

4th

test


0 -19.5 -17.9 -19.3 -20.1

10 -22.5 -21.8 -22.1 -24.0

20 -30.9 -29.0 -32.2 -30.9

In the first experiment before modify, after 4 trials, we find that the

vibration level of the trolley will decrease when loading is add on it.

In this analysis, we prove that increasing themass, reduce frequency.

Table 6.1


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2. From the data in both test,

Before Modify

Loading

(kg)

(Mean

(db)0 -19.1

10 -22.5

20 -30.6

Compare the mean vibration level before and after modification, it

shows that our design can reduce the vibration level as below chart:

After Modify

Loading

(kg)

(Mean

(db)0 -24.6

10 -32.7

20 -41.2

Fig. 6.1


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Chapter 7: Conclusion

Since vibration is characterized by the frequency and the amplitude, as

has been shown in preceding chapter. We have to aim at the above

parameters to design a product to solving the vibration problem.

We arranged two vibration tests, one for the prototype and other for

the design product. We recorded the data from the above tests and

compared these data. We made a vibration chart to represent our

finding, and it showed that the product which installed the anti -

vibrators have lower decibel than not installed.

The reasons of phenomenon are the amplitude of oscillation is

minimized by damping effect and also the frequency is reduced by

increasing the weight of the mass on the trolley. It means two

parameters are changed to cause the decease of decibel.

This finding proves that our design product (anti vibrators) can

achieve our target that minimizing the vibration level of the goods

trolley during move on a rough road.

Although the design successfully reduces the vibration level, some

problems are existed in our design. Since we did not have the drilling

machine and the holes may not be drilled accurately on the marked

location by electric hand drill, we need to enlarge the holes for fitting

the anti vibrator installation. During the test, we just push the

trolley by hand and no equipment monitors the speed of trolley so this

is the main factor to affect the accurate of the testing result.


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Chapter 8 Reflection on the Learning Experience

Name: Li Ka Kin Student ID: 1094826t

This project is a great experience and opportunity for me to learn how

to build from zero to a whole product for solving the problem. I am so

enjoyed the development process and satisfied the finished product. I

really have learned so much in this project. While you are effort to find

the information and sample to design your product, you will study lot

of academic information and your knowledge also improve so much. It

is an effective method for learning. Finally, this project can be finished

smoothly, thanks my group mates for their good-cooperation and

effort. I am so pound of them. Thanks.

Name: Yu Sin Him Student ID: 10951673t

I got a valuable experience during this project. Initially, our group

decided to design an automatic braking system for the good trolley. At

the beginning of project, we had full of ideas about the automatic

braking system. We found that our ideas all are not function after we

communicated with ourselves and hear the recommendation of teacher.In above event, the experience enriched my learning and strengthened

my communication skills. It will be a positive impact on my study even

career path. After that, we changed the topic from braking system to

anti-vibrator. During process of project, we met many design problems

on the anti-vibrator such as friction blocked the movement, wheels

sway In design process, we also appeared disagreement of opinions

between group mates .At last, we also can choose the better method

to solve the problem via a proper communication. So, I think that a

proper communication was important to ensure smooth collaboration

with each other Apart from learning vibration knowledge; I also learnt

teamwork is an important parameter of a successful project.


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Name: Chow Chi Hin Student ID: 10947936t

In this project, I am the design manager in our group. In the meetings,

I try to bring out the ideas for the project. Through this process, I

must have a clear concept of the design and do the presentation to my

group mates. After the modification part, we face some problem which

affecting our testing result. To solve those problems, we try to collect

all suggested solution and find out the suitable one by using my

knowledge of vibration. Besides, I also get the firsthand experience in

doing a project from problem identification to idea implement. It can

help my future continuality studying.

Name: Wong Tsz Yu Student ID: 10953120t

First of all, I should thank all of my group mates. During the project,

we face some barrier. There are many steps to connect the spring with

the trolley. This is the most difficult part of the project, since the

spring should be installed between the wheels and the base of the

trolley.

Second, I have learnt some technical knowledge form this design

project. For the push trolley, a hard spring is more suitable for our

situation. Due to the heavy loading of the trolley in real life, the spring

system will be broken, if we use soft spring. Thats mean, we should

choose the spring with larger spring constant.


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Reference

Reference website:

Vibration parameter

www.mech.gla.ac.uk/~sharpj/vibration.pdf

Vibration theory

www.newagepublishers.com/samplechapter/001216.pdf

Logarithmic Frequency Scaling

http://www.maintenanceworld.com/Articles/DLIEngineering/Whatis3.htm

Reference book:

Theory& formula of vibration

Vector Mechanics for Engineers Dynamics

Author: FERDINAND P.BEER, E.RUSSELL JOHNSTON,JR. &PHILLIP J. CORNWELL

Process of vibration analysis

The Vibration Analysis Handbook

Author: JAMES I. TAYLOR


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Appendix(a)Project Management

ProjectWorkSchedu

le


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(b)Manpower Management

Group

member

Project Role Activities Carried out

Li Ka Kin Project Manager Design, Make the product,

Test, Work distribution,

Organize the activities,

Control the progress and

Quality of works

Chow Chi Hin Design Manager Identify the problem of

prototype, Design, Make the

product and Test

Yu Sin Him Design Manager Identify the problem of

prototype, Design, Make the

product and Test

Wong Tsz Yu Marketing Manager Purchase, Financial

management, Record the

activities and Draw the

design layout


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(c)Financial Management

No.1 Item Description Receipt/invoice No. Price (HKD)

1 Goods Trolley 1 no. Not provided $170

2 Round File 1 no. Not provided $52

3 Springs 4 nos. Not provided $200

Total: $422-

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