design of test rig for bending and torsion of vehicle...

DESIGN OF TEST RIG FOR BENDING AND TORSION OF VEHICLE STRUCTURE

MUHAMAD ARIF FAHMI BIN ABDUL WAHAB

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

‘I/We* admit that I/we* have read this dissertation and in my/our* opinion this

dissertation is satisfactory in the aspect of scope and quality for the bestowal of

Bachelor of Mechanical Engineering (Automotive)

Signature : …………………………………….

Supervisor Name (I) : Mr. Ahmad Bin Rivai

Date : …………………………………….

Signature : …………………………………….

Supervisor Name (II) : Prof. Dr. Md. Radzai Bin Said

Date : …………………………………….

DESIGN OF TEST RIG FOR BENDING AND TORSION ON VEHICLE STRUCTURE

MUHAMAD ARIF FAHMI BIN ABDUL WAHAB

This report was submitted in accordance with the partial requirements for the honor of Bachelor of Mechanical Engineering (Automotive)

Faculty of Mechanical Engineering Universiti Teknikal Malaysia Melaka

APRIL 2009

ii

“I verify that this report is my own word except summary and extract that every one

of it I have clarify the resource”

Signature : ...............................................................

Author’s Name : Muhamad Arif Fahmi Bin Abdul Wahab

Date : 18 MAY 2009

iii

Dedicated

To my beloved Mum and Dad,

To my respectful Supervisor,

To my honorable Lecturers,

&

To my fellow Friends.

iv

ACKNOWLEDGEMENT The writer would like to say thanks to writer Supervisor, Mr. Ahmad Rivai

for his guidance and supports on writer during the Projek Sarjana Muda’s completion

period.

The co-operation given by the laboratory management especially the

technicians that involve in helping the completion of writer project are appreciated.

Acknowledgement is also dedicated to all people and personnel who whether

directly or indirectly involved in completing this project. Hope this report will be a

reference for other student in the future.

v

ABSTRACT Test Rig for bending and torsion on vehicle structure was used to measure the

deformation of the structure and measuring the loads produce on all tires during

bending and torsion case. In designing this test rig, the total loads from the vehicle

structure have been identified under bending and torsion case. The test rig function

to produce the torsion and bending case and the loads is measured by using the load

cell. The test rig is attached to the vehicle structure using a universal vehicle-test rig

attachment. Finite element method is used to validate the design whether it is strong

enough or not. If not, then the several researches will be done to repairing the

design.

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ABSTRAK

Rig ujian bagi kilasan dan lenturan terhadap struktur kenderaan in digunakan

atas tujuan untuk mengukur herotan yang terhasil pada struktur, dan juga untuk

mengukur daya yang bertindak pada kesemua tayar semasa keadaan lenturan dan

kilasan pada struktur kenderaan. Dalam merekabentuk rig ujian ini, keseluruhan

daya yang terhasil dari struktur kenderaan semasa kilasan dan lenturan perlulah

dikenalpasti. Rig ujian ini berfungsi dalam mewujudkan keadaan lenturan dan

kilasan selain daya yang bertindak semasa keadaan-keadaan tersebut diukur

menggunakan ‘load cell’. Rig ujian ini akan disambungkan pada struktur kenderaan

melalui penyambung universal struktur kenderaan-rig ujian. Setelah siap rekabentuk

terakhir bagi rig ujian ini, Kaedah Unsur Terhingga digunakan untuk memastikan

bahawa rig ujian ini selamat digunakan atau tidak. Jika rig ujian ini tidak selamat

digunakan, beberapa kajian tambahan akan dilakukan bagi memperbaiki rekabentuk

sedia ada.

vii

TABLE OF CONTENT

CHAPTER

TOPIC

CONFESSION

DEDICATION

ACKNOWLEDGEMENT

ABSTRACT

ABSTRAK

TABLE OF CONTENT

LIST OF TABLES

LIST OF FIGURES

LIST OF SYMBOLS

LIST OF APPENDICES

PAGE

ii

iii

iv

v

vi

vii

x

xi

xv

xvi

CHAPTER 1 INTRODUCTION

1.1 Background

1.2 Problem Statement

1.3 Objectives

1.4 Scope

1

1

2

2

viii

CHAPTER TOPIC

PAGE

CHAPTER 2 LITERATURE REVIEW

2.1 Background

2.2 Principle of Design and Stress

Analysis

2.2.1 Material

2.2.2 Stress

2.2.3 Design Factors

2.2.4 Buckling

2.2.5 Finite Element Method

2.3 Torsion & Bending on Vehicle

Structure

2.3.1 Bending Case

2.3.2 Torsion Case

2.4 Test Configuration

2.4.1 Static Bending Test

2.4.2 Static Torsion Test

2.5 Test Rig Design

2.5.1 Previous Design

2.5.2 Test Rig-Vehicle Attachment

3

3

4

4

6

7

10

12

12

14

15

17

17

19

19

22

CHAPTER 3

METHODOLOGY

3.1 Methodology Planning

3.2 Project Workflow

3.3 Design Specification

3.4 Design Selection

3.4.1 Test Rig Frame Structure

3.4.2 Test Rig Additional

Structure

3.4.3 Load Measurement Device

3.4.4 Test rig-Vehicle Attachment

3.5 Geometrical Dimension

24

25

26

27

27

29

32

34

38

ix

CHAPTER TOPIC

3.6 Material Selection

3.7 Strength Calculation

3.8 Finite Element Analysis

3.8.1 Individual Analysis

3.8.2 Test Rig Frame Analysis

PAGE

40

41

47

47

49

CHAPTER 4 RESULT & DISCUSSION

4.1 Final Design

4.2 Finite Element Analysis Result

51

58

CHAPTER 5 CONCLUSION & SUGGESTION

5.1 Background

5.2 Conclusion

5.3 Suggestion

67

67

68

REFERENCES

APPENDICES

70

72

x

LIST OF TABLES

NO.

TITLE PAGE

2.2.0

2.2.1

2.2.2

3.4.0

3.4.1

3.8.2

Guidelines on choosing design factor for

ductile material

(Source: Robert L. Mott (2004))

Guidelines on choosing design factor for

brittle material


Values of K for effective length, Le = KL, for

different end connections


Advantages and Disadvantages of each height

adjuster type

Data of vehicles dimensions and weights

Points coordinate for bar element of the test

rig

7

7

8

31

38

50

xi

LIST OF FIGURES

NO.

TITLE PAGE

2.2.0

2.2.1

2.3.0

2.3.1

2.3.2

2.4.0

2.4.1

2.4.2

2.5.0

2.5.1

2.5.2

Cutting element or pieces structure

(Source: Ahmad Rivai (2007))

Example of finite element on structure

(Source: Ahmad Rivai (2007))

Vehicle Bending Case

(Source: Robertson John (2002))

Typical passenger vehicle bending loads


Vehicle Torsion Case


Vehicle Structure with Bonded / Bolted Parts

(Source: Porsche Engineering Services, Inc.)

Vehicle Structure on Test Rig for Static Bending


Vehicle Structure on Test Rig for Static Torsion


Test Rig for Static Bending


Test Rig for Static Torsion


UTM 1998 test rig design without front & rear

body attachment column

(Source: Zakariah, A.M (1998))

10

11

12

13

14

15

17

19

20

20

21

xii

NO.

2.5.3

2.5.4(a)

2.5.4(b)

2.5.4(c)

3.2.0

3.4.0

3.4.1

3.4.2

3.4.3

3.4.4(a)

3.4.4(b)

3.4.4(c)

3.4.4(d)

3.4.5

3.4.6

3.4.7

3.4.8(a)

TITLE

Strut Mount Designs

(Source: Monroe Shocks & Struts (2008))

Inner Plate Design


Centre Sleeve Design


Spacer Bushing Design


Project Workflow and Methodology

Front view of x-direction adjustable link

attachment between left side and right side for

front and rear frames

Isometric view of z-direction adjustable link

between front and rear frame with support

structure on all links

Example diagram of creating Bending case on

vehicle structure

Example diagram of creating Torsion case on

vehicle structure

Changeable column with various height

Fixed column with scissor jack

Fixed column with worm/helical gear jack

Fixed column with hydraulic jack

Total load direction to load measurement device

Position Load Measurement Device on the test rig

Example of Compression and tension Load cell;

Pancake-type and S-type

(Source: Puls Elektronik Sistemleri Ltd. (2008))

BMW 3 series E46 1998 same rear and front

suspension system as BMW 3 series E36 1997

(Source: Reimpell, J et al. (2001))

PAGE

23

23

23

23

25

28

28

29

30

30

30

31

31

33

33

34

35

xiii

NO.

3.4.8(b)

3.4.8(c)

3.4.9(a)

3.4.9(b)

4.1.0(a)

4.1.0(b)

4.1.0(c)

4.1.0(d)

4.1.0(e)

4.1.0(f)

4.1.0(g)

4.1.0(h)

4.1.1

4.2.0(a)

4.2.0(b)

4.2.0(c)

4.2.0(d)

4.2.0(e)

4.2.0(f)

4.2.0(g)

4.2.0(h)

4.2.0(i)

4.2.0(j)

4.2.0(k)

TITLE

Example of front axle Mc-Pherson strut for Lancia

Delta and BMW Roadster Z3)


BMW 3series (1997) Multi link rear axle

suspension type


Top view of rear body attachment and the position

of rear body attachment on test rig column

Side view of front vehicle-test rig attachment part

Front/Left frame

Front/Right frame

Rear/Right frame

Rear/Left frame

Front connector (ball joint base)

Rear Connector

Front/Left additional column

Test rig assembly

Load cell reference drawing

(Source: FUTEK Adv Sensor Tech. Inc. (2008))

FEA result for column (Stress Tensor)

FEA result for column (Displacement)

FEA result for column (Eigenvectors)

FEA result for front connector (Stress Tensor)

FEA result for front connector (Stress Tensor)

FEA result for front connector (Displacement)

FEA result for rear connector (Stress Tensor)

FEA result for rear connector (Displacement)

FEA result for test rig frame (Von Misses Axial)

FEA result for test rig frame (Displacement)

FEA result for test rig frame (Eigenvectors)

PAGE

35

36

36

37

53

53

54

54

55

55

56

56

57

58

59

59

60

60

61

62

62

63

64

64

xiv

NO.

4.2.0(l)

4.2.0(m)

4.2.0(n)

TITLE

FEA result for test rig frame – torsion load (Von

Mises Axial)

FEA result for test rig frame – torsion load

(Deformation)

FEA result for test rig frame – torsion load

(Eigenvectors)

PAGE

65

66

66

xv

LIST OF SYMBOLS

F

A

τmax

T

J

c

r

I

Le

K

Cc

E

N

σy

Pcr

Pa

P

Mzs

M zns

RF

RR

L

LF

LR

MB

σB

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

Force, kgm/s2 (N)

Area, m2

Shear stress, N/m2 (Pa)

Torque, Nm

Polar moment of inertia, m4

Radius of the shaft to its outside surface, mm

Radius of gyration, mm

Moment of inertia of the cross section, m4

Effective length, mm

Constant dependent on the end fixity

Column constant

Modulus of elasticity / Modulus young, N/m2 (Pa)

Safety factor

Yield strength, N/m2 (Pa)

Critical load, kgm/s2 (N)

Allowable load, kgm/s2 (N)

Actual applied load, kgm/s2 (N)

Dynamic load factor in bending

Dynamic load factor in torsion

Load on front axle, kgm/s2 (N)

Load on rear axle, kgm/s2 (N)

Wheelbase, mm

Distance from centre of gravity to front axle, mm

Distance from centre of gravity to rear axle, mm

Bending moment, Nm

Stress due to the bending, N/m2 (Pa)

xvi

LIST OF APPENDICES

NO.

TITLE PAGE

A

B

C

D

Working Plan for PSM 1

Working Plan for PSM 2

Ali Marzuki Zakariah Test Rig Design

Test Rig Assembly Design

72

73

74

75

1

CHAPTER 1

INTRODUCTION

1.1 Background

Test Rig for bending and torsion on vehicle structure has been widely used by

automotive car manufacturers and researchers to measure the vehicle strength and

stiffness on a static bending and static torsion case of the vehicle structure. By using

that rig, an artificial situation of bending and torsion can be produced. Moreover, the

load and the stiffness of the vehicle can be measured for static bending and static

torsion condition. Most of researcher and automotive manufacturer will then

measure the stiffness of the vehicle structure on bending condition and torsion

condition. By then, based on the result, the car manufacture or the researchers will

estimate the vehicle stiffness and modification on the vehicle structure design will be

done if needed.

1.2 Problem Statement

In Universiti Teknikal Malaysia Melaka, the learning process for subject

Vehicle Structure Analysis on Torsion and Bending has been done theoretically. It is

because, currently, there is no such laboratory equipment to conduct a test for

bending and torsion on vehicle structure. So, in a short term period, there is a need

for student to design and develop such equipment to help faculty on providing the

laboratory equipment (specifically; test rig) to support laboratory use for testing the

2

bending and torsion on vehicle structure to increase the students (specifically;

Automotive’s student) understanding on that matter.

1.3 Objective

This thesis is done to design and analyze a test rig for measuring torsion and bending

on vehicle structure.

1.4 Scopes

- Understanding on principal of bending and torsion on vehicle structure

- Study of structural design and analysis

- Design of test rig; design selection, geometrical dimension, material

selection, strength calculation and solid modeling

- Strength analysis on test rig solid model using Finite Element Method

- Report writing and documentation

3

CHAPTER 2

LITERATURE REVIEW

2.1 Background

In designing the test rig for bending and torsion, it is needed to understand the

related principle of design and stress analysis. Moreover, the test configuration and

previous test rig design must be studied so that the suitable test rigs design, which

fulfills the criteria and requirement of the test configuration, can be created.

2.2 Principle of Design and Stress Analysis

In designing the test rig, the specifications of the test rig such as functions,

design requirements and evaluation criteria must be defined clearly. According

Mott (2004), functions tell what the device must do, using general, non-quantitative

statements that employ action phrases such as to support a load, to lift a crate, to

transmit power or to hold two structural members together. Moreover he said, design

requirements are detailed, usually quantitative statements of expected performance

levels, environmental conditions in which the device must operate limitations on

space or weight or available materials and components that may be used. Whereas,

evaluation criteria are the statements of desirable qualitative characteristics of a

design that assist the designer in deciding which alternative design is optimum- that

is, the design that maximizes benefits while minimizing disadvantages.

4

To start a design on the test rig, a lot of factors must be taken into

consideration. Mott (2004) has summarized some factors to be taken into

consideration, which as listed below:

- Forces exerted by the components of the machine through mounting points such

as bearings, pivots, brackets, and feet of other machine elements

- Manner of support of the frame itself

- Precision of the system: allowable deflection of components

- Environment in which the unit will operate

- Quantity of production and facilities available

- Availability of analytical tools such as computerized stress analysis, past-

experience with similar products, and experimental stress analysis

- Relationship to other machines, walls and so on

2.2.1 Material

Selection of material has a high effect on the structure strength. The most

significant factor to evaluate the material strength is by referring to the yield

strength, σy and the modulus of elasticity, E of the material. Mott (2004) stated that,

yield strength can be defined as the portion of the stress-strain diagram where there is

a large increase in strain with little or no increase in stress. He also stated that

modulus of elasticity can be define as stress proportionality to strain when the part of

the stress-strain diagram is straight. Modulus of elasticity indicates the stiffness of

the material or its resistance to deformation.

2.2.2 Stress

Based on Mott (2004), there are three basic fundamental kinds of stress;

tensile, compressive and shear. Tensile and compressive stress, called normal

stresses, are shown acting perpendicular to opposite faces of the stress element.

Tensile stresses tend to pull on the element whereas compressive stresses tend to

5

crush it. Shear stresses are created by direct shear, vertical shear in beams or torsion.

In each case, the action on an element subjected to shear is a tendency to cut the

element by exerting a stress downward on one face while simultaneously exerting a

stress upward on the opposite, parallel face. Stress can be defined as the internal

resistance offered by a unit area of a material to an externally applied load.

σ = force/area = F/A

When a torque or twisting moment is applied to a member, it tends to deform

by twisting, causing a rotation of one part of the member relative to another. Such

twisting causes a shear stress in the member. For a small element of the member, the

nature of the stress is the same as that experienced under direct shear stress.

However, in torsional shear, the distribution of stress is not uniform across the cross

section (Mott (2004)). When subjected to a torque, the outer surface of a solid round

shaft experiences the greatest sharing strain and therefore the largest torsional shear

stress. The value of maximum torsional shear stress is found from:

τmax = Tc/J

where; c = radius of the shaft to its outside surface

J = polar moment of inertia

T = Torque

Based on Mott (2004), the behavior of members having noncircular sections

when subjected to torsion is radically different from that for members having circular

cross sections. However, the factors of must use in machine design are the

maximum stress and the total angle of twist for such members. The formulas for

these factors can be expressed in similar forms to the formulas used for members of

circular section (solid and hollow round shafts).

Τmax = T/Q

where; Q = section modulus

Based on Mott (2004), a beam is a member that carries loads transverse to its

axis. Such loads produce bending moments in the beam, which result in the

6

development of bending stresses. Bending stresses are normal stresses, that is, either

tensile or compressive. The maximum bending stress in a beam cross section will

occur in the part farthest from the neutral axis of the section. At that point, the

flexure formula gives the stress:

σ =Mc/I

where; M = magnitude of the bending moment at the section

I = moment of inertia of the cross section with respect to its neutral axis

c = distance from the neutral axis to the outermost fiber of the beam cross

section

Positive bending occurs when the deflected shape of the beam is concave

upward, resulting in compression on the upper part of the cross section and tension

on the lower part. Conversely, negative bending causes the beam to be concave

downward.

When the dimension is already fixed, the yield strength of the material can be

change to make sure the design will not failed due to bending at specify force. So,

by using the dimension, calculate the moment of the beam. Then calculate the stress

due to the bending and compare it with yield strength of the material. If the stress

due to bending is smaller than yield strength of material, thus it mean that the beam

dimension with the material used will not failed if the specify force is applied.

2.2.3 Design Factors

Based on Mott (2004), design factor, N is a measure of the relative safety of

load-carrying component. He stated that in most cases, the strength of the material

from which the component is to be made is divided by the design factor to determine

a design stress, σd sometimes called the allowable stress. Then the actual stress to

which the component is subjected should be less than the design stress. For the case

of the buckling of columns, the design factor is applied to the load on the column

rather than the strength of the material.

design of test rig for bending and torsion of vehicle...

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