“I hereby declared that I have read through this report and found that it has comply
the partial fulfillment for awarding the degree of Bachelor of Mechanical Engineering (Material and Structure)”
Signature : ………
Supervisor’s ζame : Prof. Dr. Md. Radzai Bin Said
THE STUDY OF CYLINDRICAL TUBE UNDER QUASI-STATIC LOADING
ILLY SALWANA BINTI ABD RAZAK
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“I hereby declared this report is mine except summary and each quotation that I have mentioned the resources”
Signature:……… Author’s ζame: Illy Salwana Abd Razak
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ACKNOWLEDGEMENT
The author would like to express gratitude to her supervisor, Prof. Dr. Md. Radzai Said, for his help, time and encouragement during the course of this project.
The author takes this opportunity to also thank the Faculty of Mechanical Engineering’s laboratory management for their cooperation especially to the technicians during performing experimental works at the laboratory.
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ABSTRACT
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ABSTRAK
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TABLE OF CONTENTS
CHAPTER TOPIC PAGE
DECLARATION ii
DEDICATION iii
ACKNOWLEDGEMENT iv
ABSTRACT v
ABSTRAK vi
TABLE OF CONTENT vii
LIST OF TABLES xi
LIST OF FIGURES xii
LIST OF ABBREVIATIONS AND SYMBOLS xv
LIST OF APPENDICES xviii
1 INTRODUCTION 1
1.1 Background of study 1
1.2 Objectives 2
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CHAPTER TOPIC PAGE
1.4 Chapter outline 3
2 LITERATURE REVIEW 4
2.1 Energy and momentum in car crashes 4
2.2 Crashworthiness 5
2.3 Energy absorption 7
2.3.1 Mechanical properties of energy absorbers 8
2.3.1.1 Yield strength 9
2.3.1.2 Young's Modulus 10
2.3.1.3 Strain Hardening 10
2.3.1.4 Density 10
2.3.1.5 Strain-rate effects 10
2.4 Energy absorption system 11
2.4.1 Axial crushing on single cylindrical tube 12 2.4.2 Lateral crushing on single cylindrical tube 14 2.4.3 Lateral crushing on multilayer cylindrical tubes 15
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CHAPTER TOPIC PAGE
2.5.1 Rockwell Hardness Test 18
2.5.2 Brinell Hardness Test 19
2.5.3 Vickers Hardness Testing 20
2.6 Crash test 21
2.6.1 Side impact crash testing 21
2.6.2 Ratings criteria 23
3 METHODOLOGY 25
3.1 Specimen preparation 25
3.1.1 Material used confirmation 25
3.1.2 Specimen for hardness testing 25
3.2 Hardness measurement methods 26
3.2.1 Procedure for Rockwell Hardness Test 27
3.3 Specimen for compression test 28
3.4 Compression test method 29
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CHAPTER TOPIC PAGE
4 RESULTS AND DISCUSSIONS 31
4.1 Hardness testing result and discussions 31
4.2 Compression test results 33
4.2.1 Axial loading on a single cylindrical tube 33 4.2.1.1 Comparison between experimental and theory
for axial loading 38
4.2.2 Lateral loading on a single cylindrical tube 45 4.2.3 Lateral loading on multilayer cylindrical tubes 48 4.3 Comparison between single and multilayer cylindrical
tube under lateral loading 53
4.4 Energy absorption results 54
5 CONCLUSION 56
REFERENCES
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APPENDICES
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LIST OF TABLES
NO TITLE PAGE
3.1 Rockwell scales 26
4.1 Rockwell hardness testing result 31
4.2 Hardness value converted to Brinell and Vickers 31
4.3 Dimension of cylindrical tube specimen 39
4.4 Results of cylindrical tube under axial loading 40 4.5 Comparison between experimental and theoretical value of
cylindrical tube under axial loading
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4.6 Single cylindrical tube under lateral loading 45
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LIST OF FIGURES
NO TITLE PAGE
2.1 The collisions opponent 6
2.2 Load paths on car body elements during frontal impact 7
2.3 Yield strength curve 9
2.4 Tensile tests on sheet steel at strain rate 11
2.5 Impact attenuator features “smart plastic” cylinders 12 2.6 Results for (a) cylindrical tube average diameter D=61.5mm, length
L=120.0mm, and thickness t=1.5mm
(b) Average diameter D=45.0mm, length L=150.0mm, and thickness t=1.5mm.
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2.7 The response of a CIPSS compressed under quasi-static conditions 16 2.8 The numerical and experimental force, energy-deflection response of a
CIPSS
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2.9 Hardness testing techniques 17
2.10 Hardness testing machine 18
2.11 Hardness testing apparatus 18
2.12 Hardness testing concept
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NO TITLE PAGE
2.13 Hardness testing sample result 19
2.14 Brinell number formulation 20
3.1 Hardness testing specimen 25
3.2 Hardness testing machine 27
3.3 Specimen during lathe machining 28
3.4 Finished specimen for single cylindrical tube 28
3.5 Finished welded specimen for multilayer cylindrical tubes 29
3.6 Axial loading on single cylindrical tube 29
3.7 Lateral loading on single cylindrical tube 30
3.8 Lateral loading on multilayer cylindrical tubes 30
4.1 Graph of load against displacement for single cylindrical tube for
specimen 1 34
4.2 Specimen 2 under axial loading 36
4.3 Specimen 3 under axial loading 37
4.4 Graph of load against displacement for all specimens and its average
under axial loading 38
4.5 Graph load against displacement for lateral loading for specimen 1 46
4.6 Specimen 2 under lateral loading 46
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NO TITLE PAGE
4.9 Graph of load against displacement for lateral loading on multilayer cylindrical tubes for specimen 1
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4.10 Specimen 2 for multilayer cylindrical tubes under lateral loading 51 4.11 Specimen 3 for multilayer cylindrical tubes under lateral loading 52 4.12 Graph of load against displacement for all multilayer cylindrical
tubes and its average
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4.13 Graph of compressive load against compressive extension for single and multilayer tube under lateral loading
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LIST OF ABBREVIATIONS AND SYMBOLS
A = Cross Sectional Area ( m2) E = Young’s εodulus (N/m2)
= Stress (N/m2)
LMV = Low mass vehicle SUV = Sports utility vehicles SID = Side impact dummies
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LIST OF APPENDICES
NO TITLE
A Project proposal
B Journal of The crash energy absorption of the vehicles front structure
C Journal of Numerical simulation of axial crushing of circular tubes
D Journal of lateral crushing of circular and non-circular tube systems under quasi static conditions
E Results for axial loading on single cylindrical tube
F Results for lateral loading on single cylindrical tube
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CHAPTER 1
INTRODUCTION
1.1 Background of study
Crashes occur because of various factors including the driver, vehicle, roadway and environment. Crashes are rare events. Crash and catastrophe analysis has been discussed frequently in pastimes- traditional engineering. But then, in recent time, experimental and theoretical analyses became a part of everyday planning as the world of transportation has become a major sector in the world, and the used of transports has been a necessity to peoples. The main criteria of safety issue are vehicles deceleration pulses and deformation of the compartment where good crash energy management allows increasing the safety of both, vehicles and passengers. This concept is called crashworthiness; the ability of the vehicles to prevent injuries to the occupants in the event of a collision.
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in the analysis, thus it needs more correct techniques in new modeling and calculating methods. The same goes to other energy absorption devices. As it used widely for road user safety system or even at construction site, these devices are tested many times before they are qualified.
This project investigated the crash energy absorption in the study of cylindrical tube under axial, lateral loading and multilayer cylindrical tube under lateral loading quasi statically to determine the important parameters by performing compression test.
1.2 Objectives
In this project, energy absorption, lateral or side impact in a crash will be studied theoretically. Other than that are to determine the material properties and the behaviors collapsed and energy absorbed by cylindrical tube.
1.3 Scope
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1.4 Chapter outline
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CHAPTER 2
LITERATURE REVIEW
2.1 Energy and momentum in car crashes
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2.2 Crashworthiness
Crashworthiness is defined as capability of motor vehicle structure to provide adequate protection to its occupant from injury and to its cargo from damage in the event of crash. [2] Compatibility is the important key to be considered if the best possible safety for cars of different size and weight is to be achieved, especially for the design of low mass vehicles (LMV) without excessive reduction of safety level compared to heavier cars. δεV’s could contribute to reduce fuel consumption in traffic, provided that they are able to offer a level of safety comparable to larger cars.
Compatibility in frontal collisions calls for significantly different deceleration-time curves in rigid barrier impacts for cars with different weight. Cars designed according to compatibility criteria can change future accident and injury statistics in a way that injury severity in LMV’s can be reduced significantly. This lack of compatibility is considered to be the main reason for the unfavorable appearance of small vehicles in accident statistics. The reasons for the higher injury risk for occupants of small vehicles can be found in the low mass, which results in a higher total change of velocity in car to car collisions, and in comparison to heavier cars, in a usually lower stiffness of the crush zone and the cabin structure. [3]
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Figure 2.1 The collisions opponent.
It is important to understand the basics of vehicle crash management. The basic idea is to design vehicle structures which minimize the amount of injury-causing crash energy that reaches the occupants. Generally, this can be accomplished by developing structural zones that absorb crash energy outside the passenger compartment which called "crush zones" and they collapse in a prescribed way at specified loads, thereby providing the appropriate energy absorption and deceleration of the passenger compartment. Meanwhile, passengers are protected inside the passenger compartment by restraint systems such as seat belts and air bags. There has been lot of research and development has been carried out over the years to design and integrate these systems. In the case of the crush zones, the energy is absorbed by the folding and bending deformation of the metal structure.
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be part of the load path to absorb some of the impact energy, and to transfer some of the force of the crash in order to minimize vehicle bending moment. The design objective for rails is to balance the load path into the passenger cell of the body structure so as to distribute the loads between the roof and the floor. The structure between the rails and the rockers also must be strong enough to resist plastic deflection into the passenger space. To allow proper functioning of the passenger restraint system, the bending moment on the passenger compartment must be limited to avoid collapse of the roof structure and floor bending. Other than axial collapse resulting from front and rear end crashes, bending collapse is the other common mode of energy absorption in automotive structural components. A-pillars, windshield headers and roof side rails are typical structural members where combined forces cause bending mode collapse. Such collapse is typically caused either by buckling of the compressed surface or by cracking and tearing of the surface under tensile stress. Buckling is the preferred mode of collapse because it results in a more stable and predictable energy absorption. [5]
2.3 Energy absorption
[image:24.595.189.431.600.728.2]In term of vehicles, during the frontal crash, the longerons absorb most energy of all vehicles construction elements as shown in Figure 2.2 by load paths on car body elements during frontal impact. In order to assess the crashworthiness of longerons, the crash analysis is performed.
