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DECLARATION OF THESIS / UNDERGRADUATE PROJECT PAPER AND COPYRIGHT

Author’s full name : MOHD AMIRUL AZRI BIN MAHAT

Date of birth : 4 JANUARY 1990

Title : FINITE ELEMENT MODELING OF ARCAN TESTING METHOD

SPECIMEN UNDER DIFFERENT LOADING CONFIGURATION

Academic Session: 2013/2014

I declare that this thesis is classified as :

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SIGNATURE SIGNATURE OF SUPERVISOR

900104-10-5899 DR. SHUKUR BIN ABU HASSAN (NEW IC NO. /PASSPORT NO.) NAME OF SUPERVISOR

Date : 24 JUNE 2014 Date : 24 JUNE 2014

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UTM(FKM)-1/02

Faculty of Mechanical Engineering

Universiti Teknologi Malaysia

VALIDATION OF E-THESIS PREPARATION

Title of the thesis : FINITE ELEMENT MODELING OF ARCAN TESTING METHOD

SPECIMEN UNDER DIFFERENT LOADING CONFIGURATION

Degree: BACHELOR OF ENGINEERING (MECHANICAL)

Faculty: FACULTY OF MECHANICAL ENGINEERING

Year: 2013/2014

I MOHD AMIRUL AZRI BIN MAHAT

(CAPITAL LETTER)

declare and verify that the copy of e-thesis submitted is in accordance to the Electronic Thesis and

Dissertation’s Manual, Faculty of Mechanical Engineering, UTM

_____________________

(Signature of the student)

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(Signature of supervisor as a witness)

Permanent address:

NO 2A BLOK 45

PANGSAPURI TNB KM 16

JALAN KAPAR

42200 KAPAR

SELANGOR

Name of Supervisor: DR.SHUKUR BIN ABU

HASSAN

Faculty: FACULTY OF MECHANICAL

ENGINEERING

Note: This form must be submitted to FKM, UTM together with the CD.

“I hereby declare that I have read this report and in my opinion this report is

sufficient in terms of scope and quality for the award of Bachelor Degree of

Engineering (Mechanical).”

Signature :…………………………………..

Name : DR. SHUKUR BIN ABU HASSAN

Date : 24 JUNE 2014

i

FINITE ELEMENT MODELING OF ARCAN TESTING METHOD SPECIMEN

UNDER DIFFERENT LOADING CONFIGURATION

MOHD AMIRUL AZRI BIN MAHAT

A report submitted in partial fulfillment of the

requirements for the award of the degree of

Bachelor of Engineering (Mechanical)

Faculty of Mechanical Engineering

Universiti Teknologi Malaysia

JUNE 2014

ii

I declare that this report entitled “Finite Element Modeling of Arcan Testing Method

Specimen under Different Loading Configuration” is the result of my own research

and experience except as cited in the references. The report has not been accepted for

any degree and is not concurrently submitted in candidature of any other degree.

Signature :…………………………………..

Name : MOHD AMIRUL AZRI BIN MAHAT

Date : 24 June 2014

iii

To my beloved family, teachers and lecturers, supportive friends and acquaintances

who have put most effort and give encouragement to me towards my study

iv

ACKNOWLEDMENT

Alhamdulillah, I would like to express my grateful to Allah SWT for all good

things during Final Year Project period. With all of endless patience and effort, I can

finish this thesis with success.

Firstly, I would like to thank to my supervisor, Dr. Shukur Abu Hasan for his

kindness and guidance during this one year of research. He committed himself with

great dedication on the supervision of my final year project. I have gained a lot of

practical knowledge and expertise through working alongside him.

I would like to thank my parents, Mr. Mahat b. Mahmood and Mrs. Rosiah bt

Sarif for believing in my dreams and supporting the best possible way they could.

I would like to express my appreciation to those who had helped me along

with this thesis, especially to course mate that never stop sharing knowledge

everywhere and every time.

Finally, I would like to thank to these people:

• All Centre for Composite Department staff for willingness to guide me

especially during specimen preparation works.

• All Metallurgy Laboratory staff for willingness to guide me especially during

polishing epoxy specimen.

• All Mechanics of Material Laboratory staff for willingness to guide me

especially during conducting load test.

• Dr Behzad Abdi for willingness to invite me joining his ANSYS Workbench

workshop for free.

v

ABSTRACT

This project is based on the application of Arcan test method introduced by Arcan et

al to determining the shear strength and shear moduls of material. In this research, the

objective has been systematically approached using ANSYS finite element analysis software.

The approach involves investigation of the problem and analysis of the butterfly specimens

subjected to a load with different loading configuration. The condition are simulated in

ANSYS which involved CAD and finite element modelling of the butterfly specimen, and

then the finite element model is validated geometrically by ANSYS element shape checking

capability. The finite element model subjected to static structural analysis confirmed the

stress concentration and crack initiation take place which indicated cause of the failure. The

performance of tensile data of Arcan test affect by notch. Finally, this research concludes

with a proposal to revised specimen model and recommendation for further analysis.

vi

ABSTRAK

Projek ini adalah berdasarkan penggunaan kaedah ujian Arcan yang diperkenalkan oleh

Arcan et al untuk menentukan kekuatan ricih dan modulss ricih bahan. Dalam kajian ini,

objektif tertumpu secara sistematik dengan menggunakan perisian analisis unsur ANSY.

Kajian ini juga bertujuan untuk membuktikan analisis kaedha unsur terhingga adalah mampu

memberikan keputusan yang hamper sama dengan ujian makmakl. Pendekatan ini

melibatkan pengenalpastian masalah dan analisis spesimen rama-rama yang bergantung

kepada konfigurasi beban yang berbeza. Keadaan ini disimulasi dalam ANSYS yang

melibatkan CAD dan pemodelan unsur terhingga spesimen rama-rama, dan kemudian

analisis model unsur terhingga dilakukan terhadap geometri specimen. Analisis model unsur

terhingga menggunakan struktur statik mengesahkan bahawa tegasan tertumpu dan

permulaan rekahan yang berlaku menunjukkan punca kegagalan terhadap specimen. Prestasi

data tegangan ujian Arcan terjejas disebabkan oleh takuk pada specimen. Akhir sekali, kajian

ini diakhiri dengan cadangan untuk pengubahsuaian model spesimen dan cadangan untuk

analisis lanjut.

vii

TABLE OF CONTENTS

CHAPTER TITLE PAGE

TITLE i

DECLARATION ii

DEDICATION iii

ACKNOWLEDGMENTS iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF FIGURE xi

LIST OF TABLE xvi

LIST OF SYMBOLS xviii

LIST OF APPENDICES xix

1 INTRODUCTION

1.0 Introduction 1

1.1 Objective 2

1.2 Scope 3

1.3 Thesis Framework 3

2 LITERATURE REVIEW

2.0 Introduction 5

2.1 Arcan Test Method 6

2.1 .1The Evolution of Arcan Fixture and Specimen 6

2.1.2 Previous Research on Arcan Test 10

viii

2.1.3 Previous Finite Element Analysis on Arcan Test 15

2.1.4 Theoretical Background of Arcan Test 19

2.1.5 Stress Analysis 20

2.2 Standard Test Method for Tensile Properties 21

2.2.1 Previous Research on Tensile Test 22

2.3 Summary 23

3 RESEARCH METHODOLOGY

3.0 Introduction 24

3.1 Specimen Preparation and Experimental Setup 25

3.1.1 Specimen Geometry 25

3.1.2 Material Details 27

3.1.3 Mixing and Casting Process for Epoxy 28

3.1.4 Specimen Preparation for Aluminium 32

3.1.4 Strain Gauge Installation 34

3.1.6 Tensile Test Set-Up and Test Procedure 35

3.1.7 Arcan Test Setup 36

3.2 Specimen Modelling and Analysis Setup 38

3.2.1 Specimen Modelling 39

3.2.2 Input Material Data 39

3.2.3 Meshing 40

3.2.4 Boundary Condition and Loading Setup 41

3.3 Summary 41

4 RESULTS AND DISCUSSION

4.0 Introduction 42

4.1 Sample Testing Evaluation 43

4.1.1 Test –Rig Specimen Evaluation of

Tensile Method for Epoxy 43

4.1.2 Test Rig-Specimen Evaluation for Arcan

Test Method 44

4.1.2.1 Shear Test for Epoxy and Aluminium

Sample 45

ix

4.1.2.2 Tensile Test for Epoxy and Aluminium

Sample 47

4.1.2.3 Tensile Shear Test for Epoxy and

Aluminium Sample 49

4.2 Experimental Result for Arcan Test Method 51

4.2.1 Experimental Results for Shear Loading

of Epoxy 51

4.2.2 Experimental Results for Shear Loading

of Aluminium 52

4.2.3 Experimental Results for Tensile Loading

of Epoxy 52

4.2.4 Experimental Results for Tensile Loading

of Aluminium 53

4.2.5 Experimental Results for Tensile Shear

Loading of Epoxy 54

4.2.6 Experimental Results for Tensile Shear

Loading of Aluminium 55

4.3 Experimental Result for Tensile Test 56

4.3.1 Experimental Data of Tensile Test Method

for Epoxy 56

4.4 Finite Element Analysis 58

4.4.1Finite Element Analysis Result for Shear

Loading of Epoxy 59

4.4.2 Finite Element Analysis Result for Shear


4.4.3 Finite Element Analysis Result for Tensile

Loading of Epoxy 64




Shear Loading of Epoxy 69


Shear Loading of Aluminium 71

4.5 Notch Sensitivity Analysis 73

x

4.6 Tensile Test Performance Analysis 76

5 CONCLUSION AND RECOMMENDATION

5.0 Conclusion 78

5.1 Recommendation 79

REFFERENCE 80

Appendices A1-A3 82-83

xi

LIST OF FIGURE

FIGURE NO TITLE PAGE

1.1 The concept of cylinder torsion test method [4] 3

1.2 Significant section of the Arcan‟s butterfly specimen [5] 4

2.1 The early design concept of Arcan Test method [5] 8

2.2 Significant section of the Arcan‟s butterfly specimen [5] 8

2.3 Butterfly specimen bonded to aluminium circular

plate test fixture [6] 9

2.4 Modified test fixture and butterfly specimen

set-up by Yen et al. [7] 10

2.5 Arcan fixture and butterfly specimen loading

configuration [7] 10

2.6 Butterfly specimen geometry used by Yen et al. [8] 11

2.7 Mohr‟s circle constructed base principal strains of

ESLT-LB01 at 1000N case [8] 12

2.8 Brittle failure of ESLT-SW01 [8] 12

2.9 Failed axial and transverse specimen after reaching the

ultimate stress α=90° [9] 13

2.10 Shear stress-strain response from Arcan shear test [9] 13

xii

2.11 Measured axial strain profiles at centre of axial

butterfly specimen during „pure shear‟ test [9] 14

2.12 Measured axial strain profiles at centre of transverse butterfly

specimen during „pure shear‟ test [9] 14

2.13 Shear stress-strain response from Arcan biaxial

testing [9] 15

2.14 Experimental results in pure tensile of non-welded 6056T78

Aluminium specimen [10] 15

2.15 Original experimental shape and boundary condition [11] 15

2.16 Effect of notch radius on shear stress profile along gauge

section [9] 17

2.17 Effect of sharp notch on shear stress along the

gauge section [9] 17

2.18 Effect of roving orientation on the shear stress along the

gage section [9] 18

2.19 Stress field of tensile loading before rupture [12] 19

2.20 Stress field of shear loading before rupture [12] 19

2.21 Arcan fixture for shear test with different loading

configurations [9] 20

2.22 Internal mean shear and normal stress along the

‘significant section’ 20

2.23 Dumbbell-shaped specimen dimension [24] 23

2.24 Stress-strain curve of graphine reinforced epoxy [23]

3.1 Two parts of Selfix Carbofibe adhesive (a) Part A (b) Part B 27

3.2 A mixing process using low speed electric mixer 29

3.3 Flat plate attached to male part by screws

xiii

(a)Flat plate before installation

(b) Flat plate after installation 29

3.4 Casting process by pouring the mixtures into the female

mould

(a)Butterfly specimens

(b) Dumbbell-shaped specimens 30

3.5 (a) Male part attached to the female part and

(b) 10 kg mass used 30

3.6 Demoulding process 36

3.7 Surface grinding and polishing process of the specimen

(a) Mecapol P255 U polishing machine

(b) Manula polishing technique 31

3.8 Specimens ready for experiment 31

3.9 Aluminium scrap 32

3.10 (a) Milling machine (b) Specimen ready for labelling

The butterfly specimen geometry 32

3.11 Strain gauge on dumbbell specimens 33

3.12 Tensile test set-up 34

3.13 Instrumentation set-up 35

3.14 Arcan test fixture and butterfly specimen [8] 36

3.15 Attached Arcan fixture to the holder 36

3.16 Arcan fixture set-up configuration

(a)Tensile (b) Shear (c) Tensile shear 37

3.17 The butterfly specimen geometry 39

3.18 Butterfly specimen of epoxy in ANSYS 39

3.19 Properties of material in ANSYS 40

3.20 Meshed model specimen 41

3.21 Boundary condition and loading setup

(a)Shear (b) Tensile shear (c) Tensile 42

4.1 Brittle failure of T1epoxy occurred at ±0 44

xiv

4.2 Brittle failure of ES1 occurred at ±45° 46

4.3 Ductile failure of AS1specimen occurred at ±90° 47

4.4 Brittle failure of ET2 specimen occurred at ±90° 48

4.5 Ductile failure of AT occurred at ±45° 49

4.6 Brittle failure of ETS3occurred at ±30° 50

4.7 Ductile failure of ATS2Aluminium occurred at ±90° 51

4.8 Stress-strain curve for ASTM1 Specimen 59

4.9 Shear stress-strain curve of Selfix Carbofibre epoxy 61

4.10 (a) Maximum principal stress

(b) Maximum shear stress

(c) Equivalent elastic strain 62

4.11 Stress distribution along significant section

AB of Selfixe Carbofibre epoxy due to shear loading 63

4.12 Shear stress-strain curve for aluminium 64


(b) Maximum shear stress


4.14 Stress distribution along significant section AB

of aluminium due to shear loading 66

4.15 Stress-strain curve for epoxy 67


(b) Maximum normal stress


4.17 Stress distribution along significant section

AB of Selfix Carbofibre epoxy due to tensile 69

4.18 Stress-strain curve for aluminium 71

xv


(b) Maximum normal stress



of aluminium due to tensile. 73

4.21 (a) Maximum principal stress 74


of aluminium due to tensile shear load. 75

4.23 (a) Maximum principal stress 76


of aluminium due to tensile shear load. 77

4.25 Effect of notch on stress distribution of Selfix Carbofibre

due to shear load. 78

4.26 Effect of notch on stress distribution of Selfix Carbofibre

due to shear tensile. 78

4.28 Effect of notch on stress distribution of aluminium due

to shear load. 79

4.29 Stress-strain curve of Selfix Carbofibre epoxy with

different notch radius. 80

4.30 Stress-strain curve of aluminium with different notch radius 81

xvi

LIST OF TABLE

TABLE NO. TITLE PAGE

2.1 Simulation results – parameter based on Arcan

tests properties [30] 19

3.1 Chemical formulation of Selfix epoxy adhesive [8] 26

3.2 Typical mechanical and physical properties of

Selfix Carbofibe epoxy adhesive [8] 27

3.3 Material properties Selfix Carbofibe epoxy

adhesive from Shukur. A. H [8] 28

3.4 Mechanical properties of 6061 alloy [22] 28

3.5 Rossete type strain gauge specifications [25] 33

4.3 Experiment data for shear loading of ES specimens 52

4.4 Experiment data for shear loading of AS specimens 53

4.5 Experiment data for shear loading of ET specimens 54

4.6 Experiment data for shear loading of AT specimens 55

4.7 Experiment data for shear loading of ETS specimens 56

4.8 Experiment data for shear loading of ATS specimens 57

4.9 Experiment data for ASTM1 specimen 58

4.10 Test results for ASTM specimens 58

4.11 Analysis result for shear loading of Selfix

Carbofibre epoxy 60

4.12 Analysis result for shear loading aluminium 64

xvii

4.13 Analysis result for tensile loading of Selfix

Carbofibre epoxy 67

4.14 Analysis result for tensile loading of Aluminium 70

4.15 Analysis result for tensile shear loading of Selfix

Carbofibre epoxy 73

4.13 Analysis result for tensile shear loading of

aluminium 75

xviii

LIST OF SYMBOLS

F - Force

P - Force

σ - Normal Stress

τ - Shear Stress

A - Cross-sectional Area

xix

LIST OF APPENDICES

APPENDIX TITLE PAGE

A1 Type and dimension of Dumbbell shape specimen 82

A2 Engineering drawing of epoxy adhesive butterfly

specimen mould 82

A3 Engineering drawing of modified Arcan shear test

fixture 83

1

CHAPTER 1

INTRODUCTION

1.0 Introduction

The finite element method is a numerical procedure that can be applied to

obtain solutions to a variety of problems in engineering. Applications range from

deformation and stress analysis of automotive, aircraft, building, and bridge structure

to field analysis of heat flux, fluid flow, magnetic flux, seepage, and flow problem

[1]. Finite element analysis also is a numerical method of deconstructing a complex

system into very small pieces called element. The software implements equations

that govern the behaviour of these elements and solves them all; creating a

comprehensive explanation of how the system acts as a whole. These results then can

be presented in tabulated or graphical forms. This type of analysis is typically used

for the design and optimization of a system far too complex or impossible to analyse

by calculation. Systems that may fit into this category are too complex due to their

geometry, scale, or governing equations.

In 1978, Arcan et al. [2] introduced a new method of testing material shear

properties under uniform plane stress conditions by means of a specially designed

plane specimen. The fixture was used to determine shear properties for various

materials such as polymer composite, isotropic, orthotropic, ductile and brittle. The

2

compact nature of the Arcan fixture offered an advantage to obtain the shear

properties in all in-plane directions in a relatively simple manner. The Arcan fixture

also capable to produce axial, shear, and combined both forces to the test specimen.

Special case of pure shear produced on the significant section when angle α=90° was

introduced.

In recent year, many scientist use finite element analysis of Arcan test method

to validate their experiment outcome. The usage of finite element modeling in Arcan

testing method provides several result which impossible to obtain by considering

basic theoretical approach. The modified-Arcan fixture and its butterfly specimen are

designed to determine the shear moduli, non-linear stress– strain response, and

strength of thick-section pultruded composites under shear combined with different

biaxial stress conditions. The uniformity of the shear stress in studied material was

investigated. The presence of the direct stresses and their relative effect on the shear

properties is also examined. FE analyses are used to investigate the effect of notch

radius and material orthotropy on the uniformity and distribution of stresses in the

significant section of the butterfly specimen

In this study, Selfix Carbofibre Epoxy and Aluminium 6061 was chosen to be

material for Arcan test method and finite element analysis. All three loading

configuration will be perform in study to investigate the characteristic of material. In

addition to that, the studies will provide data and results on the performance of

testing method which can be comparing with common test method. The finding is

vital and will be used as a reference in future studies and projects.

3

1.1 Objective

The aim of this project is to study the behaviour of brittle and ductile

materials samples under ARCAN test method using FEA. Therefore, the following

objectives are listed as follows;

i. To model and analyse Arcan specimen geometry using FEA

ii. To study characteristics of samples material along significant section

under different loading configurations using Finite Element Software

iii. To compare the FEA results with samples testing outcomes

1.2 Scope

Firstly, the scope of this project covers the study of Arcan testing method and

specimen geometry. After that, the project focuses on the specimen preparation for

Arcan test and tensile test. Tensile test for epoxy will be conduct to obtain its

mechanical properties for finite element analysis purpose and data comparison. Later

on, Arcan test method will be conduct for Aluminium 6061 and Selfix Carbofibre

epoxy in order to obtain maximum loading which to be apply in finite element

analysis. The specimen is model and analyse using ANSYS Workbench software.

Lastly, the project focuses on data collection for comparison analysis and discussion

which will be including in report writing.

1.3 Thesis Framework

The thesis is structured according to the overall programme methodology by

taking into consideration the most prioritised research works. The arrangement of the

overall thesis presentation framework is briefly described as follows;

4

i. In Chapter 2, the study focuses on reviewing the technical aspects of

Arcan test method applications and studying finite element analysis

applications from previous researchers.

ii. In Chapter 3, the study focuses on research methodology which

includes specimen preparation, testing procedure, specimen modelling

and finite element analysis.

iii. In Chapter 4, the discussion focuses on outcomes of load test on the

experimentation specimens and finite element analysis of epoxy and

aluminium. The discussion also focuses on stress distribution on

butterfly specimens, the performance of Arcan testing method for

tensile test and notch sensitivity effect on result outcome.

iv. In Chapter 5, the research programme findings conclude by focusing

on the loading configuration on the test samples. From the research

programme experience, a few suggestions have been made to conduct

and explore more studies on the testing performances.

5

CHAPTER 2

LITERATURE REVIEW

2.0 Introduction

The mechanical properties of material play important role in engineering

application. The selection of material also is important to provide sufficient material

integrity. Many test method proposed by scientist as an alternative to determine

properties of material. In general, the typical shear test method used to determine the

shear properties of most materials is the cylinder-torsion test method. The method is

able to determine the shear properties by analysing stress elements at various angles

or distances from cylindrical section centre as shown in Fig. 1. Unfortunately, this

method has a weakness that it is unable to produce a significant section on the

specimen, and the grips strongly influence the state of stress [3].

Fig. 2.1: The concept of cylinder torsion test method [3]

6

In 1978, Arcan et al. [2] introduced a new method of testing material shear

properties under uniform plane stress conditions by means of a specially designed

plane specimen, as shown in Fig 1.2. The fixture was used to determine shear

properties for various materials such as polymer composite, isotropic, orthotropic,

ductile and brittle. The compact nature of the Arcan fixture offered an advantage to

obtain the shear properties in all in-plane directions in a relatively simple manner.

The Arcan fixture also capable to produce axial, shear, and combined both forces to

the test specimen. Special case of pure shear produced on the significant section

when angle α=90° was introduced.

Fig 2.2: Significant section of the Arcan‘s butterfly specimen [2]

2.1 Arcan Test Method

2.1.1 The Evolution of Arcan Fixture and Specimen

Arcan et al. [2] introduced biaxial test fixture called Arcan fixture to produce

biaxial states of stress. The design concept of Arcan fixture enabled the obtaining in

any in-plane directions of shear properties. Fig. 2.1 show early design concept of

Arcan Fixture.

7

Fig. 2.3: The early design concept of Arcan Test method [2]

In the early design concept, the fixture was fabricated from material to be

tested. The combinations of tension and shear loading are possible to be produced

when applying different directions tensile force, F. This method provide pure shear

loading when the angle α= 90º. The principle behind the geometry of the specimen is

that in the pure shear zone, the isostatics will intersect the sheared cross-section (AB

in Fig. 2.2) at an angle of α=±45º.

Fig. 2.4: Significant section of the Arcan‘s butterfly specimen [2]

In 1978, Arcan et al. [5] have modified the previous test fixture by bonding

the test specimen on the aluminium circular plane with anti-symmetric cut-outs as

shown in Fig. 2.3.

8

Fig.2.5: Butterfly specimen bonded to aluminium circular plate test fixture [5]

In 1988, Yen et al [6] continued on development of Arcan test fixture by

modified Arcan fixture into two pairs of stainless steel parts, each pair equivalent to

one half of the original Arcan fixture. A butterfly shape cut-out was fabricated to half

the thickness in each part to house the specimen. Three holes were drilled for screws

at each part to allow for the tightening of the two parts together. The butterfly

specimen which was joined on either side of two half circular grips as in Fig. 2.4

were connected to a universal testing machine at the top and bottom, respectively.

The grips together with the butterfly specimen formed a circular disk with two anti-

symmetric cut-outs.

Fig. 2.6: Modified test fixture and butterfly specimen set-up by Yen et al. [6]

Voloshin and Arcan [6] used this method in determining the through

thickness and longitudinal shear modulus in unidirectional laminated FRP composite.

9

The Arcan test also used to determine the strength of thick section pultruded

composites under shear and non-linear stress-strain response, combined with

different biaxial stress conditions. The modification proposed by Yen et al. [6]

included bolting a butterfly shaped specimen between two identical halves of the

Arcan fixture. Fig. 2.5 shows a schematic of the modified Arcan fixture with the

butterfly specimen.

Fig. 2.7: Arcan fixture and butterfly specimen loading configuration [6]

The fixture was flexible to accommodate the pultruded specimens with

various thicknesses. The butterfly specimen design is shown in Fig 2.6. Six units of

6.4 mm diameter sleeve bolts were used to transfer the load from the fixture to each

side of the specimen and the bolts were hand-tightened. The significant section of the

specimen AB was designed in such way that the state of stress on AB was as uniform

as possible.

10

Fig. 2.8: Butterfly specimen geometry used by Yen et al. [6]

2.1.2 Previous research on Arcan Test

In 2007, Shukur A. H [7] conducted an experiment to determine mechanical

performance of structure epoxy adhesive exposed to tropical condition. A brittle

epoxy adhesive was tested using Arcan test method in pure shear condition to

determine shear strength and shear modulus. Based on the data from strain gage, the

pure shear state is proven reliable since the value of average strain at zero (Fig. 2.7).

The shifted of shear state location are due to experimental error that impossible to

avoid. The pure shear state also become more reliable since the fracture surface was

found in 45°as shown in Fig. 2.8, which also the direction of tensile principal stress.

11

Fig 2.9: Mohr‘s circle constructed base principal strains of ESLT-LB01 at 1000N

case [7]

Fig 2.10: Brittle failure of ESLT-SW01 [7]

A group of researcher conducted a testing method to examine a modified

Arcan fixture for measuring the non-linear stress-strain shear response in thick

section pultruded FRP composite materials [8].

The specimen were fabricated from one pultruded plate with 12.2mm

thickness and has been cut by water-jet machining system into butterfly shape with

precise tolerance of ±0.08 mm. The load was applied by using MTS 810 servo

hydraulic machine with 90° load angle to perform ―pure shear‖.

12

The results of from the experiment indicate that Arcan test fixture is capable

for the measurement of the entire response up to ultimate failure. The examination of

the α = 90° reveal that the failure initiate at the notch and propagate along section

AB as show in Fig. 2.9.

Fig. 2.11: Failed axial and transverse specimen after reaching the ultimate stress

α=90° [8].

From their stress-strain curve plotted, it can be noted that all specimens

perfectly failed in brittle behaviour. The linearly propagated shear stress- strain

curves in Fig.2.10 indicate a state of pure shear was present during the testing.

Although the present of small axial strain, it doesn‘t affect the shear response

observed throughout its non-linear response [8].

Fig.2.12: Shear stress-strain response from Arcan shear test [8]

13

Strains of ε −45 and ε+45 are linearly with shear stress and almost symmetry

along x-axis as shown in Fig. 2.11 and Fig. 2.12. This result proves that the testing

method was reliable as the strain data obtained were balanced in each direction. The

testing method also suitable in determine the shear properties, shear modulus, and

shear strain of brittle materials, especially for Fibre Reinforced Polymer composites.

The failure of Arcan test specimens also depend on the angle of biaxial load as

shown in Fig 2.13.

Fig 2.13: Measured strain profiles at centre of axial butterfly specimen during ‗pure

shear‘ test [8]

Fig 2.14: Measured strain profiles at centre of transverse butterfly specimen during

‗pure shear‘ test [8]

14

Fig 2.15: Shear stress strain response from biaxial testing [8]

In 2006, Samuel et al [9] used Arcan test method to study material behaviour

in 6056T78 Friction Stir Welding (FSW) specimens. Arcane tensile test and tensile

test of non-welded (base material) was firstly introduced in order to determine any

comparison parameter. From the result, specimen shapes are likely influence the data

especially during the necking process. The maximum strain achieve before rupture

has found differ around 9% for both test as shown in Fig. 2.14.

Fig. 2.16: Experimental results in pure tensile of non-welded 6056T78 Aluminium

specimen [9]

15

2.1.3 Previous research of Finite Element Analysis of Arcan test

Finite Element Method was applied to nonlinear problems and large

deformation in late 1960s and early 1970s [1]. Nonlinear analysis enables a design

engineer to make sound design decisions. In nonlinear stress analysis is becoming

important for designers in order to employing a wider variety of materials in a

multitude of different applications.

Finite element analysis also has been considered by most scientists in their

research and experiment. An error occur during experiment has made the finite

element analysis are more relevant to produce accurate data. In Arcan test method,

the result obtain still are not accurate even strong theoretical background. The

problem become more complicated since orthotropic type of material was

introduced.

In year 2010, R. Rinaldi et al [10] conducted a research on modelling

structure polycarbonate. A finite element method is used in order to confirm the

prediction capability of Arcan test in various loading condition. Analysis for ―pure

shear‖ loading show boundary condition proposed for the shear test was set to be

fixed at left segment of specimen with the direction of load are based on Arcan test

practice (α=90°) at right segment as shown in Fig. 2.15. Roller condition at right

segment of specimen only applied at ―pure shear‖ loading.

Fig. 2.17: Original experimental shape and boundary condition [10]

16

In year 2003, Rani El-Hajjar at el [8] used finite element analyses of to

stimulate the effect of notch radius and material orthotropic on the uniformity and

distribution of stresses in the significant section of the butterfly specimen of Arcan

test method under shear loading. There were three notch radii selected to determine

the most appropriate radius of 1.27mm, 2.54mm and 5.05mm. Fig. 2.16 shows the

shear stress profile along the gauge section for FRP axial orientation. A normalised

stress profile near to 1 was found near the centre for the specimen with a notch radius

of 2.54 mm.

Fig. 2.18: Effect of notch radius on shear stress profile along gauge section [8]

The simulation by isotropic assumption and orthotropic value showed non-

uniformity of stress profile in the significant section resulted in a lower stress

concentration near the notch tip, with a more gradual stress built up compared to the

sharp notch as shown in Fig. 2.17. The normalized shear stress closer to 1.0 was

found near the centre as it far from notch effect at the tip.

17

Fig. 2.19: Effect of sharp notch on shear stress along the gauge section [8]

By considering the effect of roving orientation on shear stress along the

significant section as shown in Fig. 2.18, the value show that axial (90°) fibre

produce more uniform stress compare to transverse (0°) fibre and isotropic material.

Transverse fibre resulted highest stress concentration at the notch tip.

Fig 2.20: Effect of roving orientation on the shear stress along the gage section [8]

In year 2008, David Delsart et al [11] used finite element method to study the

material through thickness and out- of-plane shear properties identified of Fibre

18

Reinforced Composite from Arcan test method. The stress concentration generated

at the mid-section of the specimen was observed until fracture occurs as shown in

Fig. 2.19 and Fig 2.20. From the result, max tensile and shear load of numerical was

found less than experiment with -40% and -24% respectively.

Table 2.1: Simulation results – parameter based on Arcan tests properties [11]

Load configuration Experimental Max. Force (N) Numerical Max. Force (N)

0° 1904 1146

90° 2535 1928

Fig. 2.21: Stress field of tensile loading before rupture [11]

Fig. 2.22: Stress field of shear loading before rupture [11]

19

2.1.4 Theoretical background of Arcan Test Method

The modified Arcan fixture and its butterfly shape specimen capable to

produce pure shear and biaxial stress conditions, as shown in Fig. 2.21. The shear

response from various biaxial stress states can be obtained in a relatively simple

manner by varying the angle of α at which the load is applied. A special case of ‗pure

shear‘ can be produce section AB when α = 90 degree. The basic concept of

configurations is that the Arcan test set-up has a well-defined as significant section

AB, where the stresses are assumed to be uniform. Fig. 2.22 shows the significant

section at the centre of the butterfly specimen. This uniformity of stresses is a result

of appropriate geometrical parameters of the butterfly specimen. Another outcome of

the butterfly type geometry is the stresses at the significant section are the highest

because of small cross-sectional area in segment and thus, initial yield or failure is

more likely to occur within the section.

Fig. 2.23: Arcan fixture for shear test with different loading configurations [8]

20

Fig. 2.24: Internal mean shear and normal stress along the ‘significant section’ [8]

The mean normal stress, σ y, and the mean shear stress, τ xy at the significant

section are defined in a local coordinate system, where the x-axis is perpendicular

and the y-axis is parallel to the significant section. Both components of stress can be

directly determined from the forces that are transmitted by the joints between the

testing machine and the Arcan grips, as previously shown in Fig. 2.21.

For pure shear testing, the forces that act along axis of the universal testing

machine referred as the vertical applied force, Py while perpendicular to the universal

testing machine is referred to as the horizontal force, Px. The angle, α, indicated the

angel between perpendicular axis of significant section to the load direction of

testing machine. Finally, A denotes the cross-sectional area of the specimen

significant section, (i.e. width x thickness).

2.1.5 Stress Analysis

The force applied to the rig as shown in Fig. 2.22 will produced shear and

normal stress at section AB. In order to determine the normal stress σx and the

shearing stress τxy acting on the face perpendicular to the x-axis, an element in state

21

of equilibrium to the x and y axes shall be considered. By assuming the uniform

stresses on the significant section AB, the equilibrium analysis that on significant

section AB as shown in Fig. 2.16 write as

→ Σ Fx = 0; Pcosα - σ xx A = 0

σ yy =

[2.1]

↑ Σ Fy = 0; Psinα -τ xyA = 0

τ xy =

[2.2]

The rectilinear portions of the cut-outs element are oriented at ± 45 shows the

principal stresses in the vicinity are also in these directions. It follows that τxy on AB

as given by equation [2.5] is a principal shear stress. Therefore on AB,

σ xx = σ yy =

[2.3]

and the principal stresses are

σ 1 = σ xx + σ xy =

[2.4]

σ 2 = σ xx - σ xy =

[2.5]

2.2 Standard Test Method for Tensile Properties

According to ASTM International [24], the standard method for tensile test of

plastic material is subjected under D638. This test was specified to unreinforced and

22

reinforced in the form of standard dumbbell-shaped test when tested under defined

condition of temperature, humidity, pre-treatment and testing machine speed. For the

rigid and semi-rigid plastic, the specimen should conform to the dimension as shown

in Fig. 2.23.

Fig. 2.25: Dumbbell-shaped specimen dimension [12]

2.2.1 Previous Research on Tensile Test

In year 2014, Shahin Shadlou [13] used ASTM D638 to measure the Young

Modulus of graphine reinforced epoxy under different strain rates. There were 4

strain rates selected to determine the behaviour of 0.01, 0.1, 1, 10/s under tensile

loading. Typical stress-strain curve for each strain rates under tensile loading are

illustrated in Fig. 2.24. The Young modulus of graphine reinforced increase with

strain rates.

23

Fig.2.26: Stress-strain curve of graphine reinforced epoxy [13]

2.3 Summary

The literature on the Arcan testing method was briefly discussed in this

chapter. In this chapter the Arcan fixture development process was shown, which is

including the time-line of Arcan fixture, how the rig works, advantages of significant

section on butterfly specimen finite element analysis and the reliability of the Arcan

test result. As a conclusion, the Arcan test method can be used to determine the

mechanical properties of material such as shear strength and shear modulus.

24

CHAPTER 3

RESEARCH METHODOLOGY

3.0 Introduction

In this section, the discussion focused on the specimen preparation,

experimentation, instrument and measurement. Every topic was discussed in detail in

order to make the objective of this study can be achieved.

For this study, nine sample of butterfly specimen were produced from each

Selfix Carbofibre and Aluminium 6061. Three samples from group material were

selected for each loading configuration. Three sample of dumb-bell specimen were

produced in this study to determine the tensile modulus of Celfix Carbofibre. Instron

Universal Testing Machine Series IX Model 4206 used for the test. After tensile for

dumb-bell specimen was carried out, mechanical properties Selfix Carbofibre were

recorded for finite element analysis material requirement. The maximum strength for

each loading configuration will be record to represent the maximum load applied in

ANSYS.

25

3.1 Specimen Preparation and Experimental Setup

3.1.1 Specimen Geometry

The specimen size 60 mm long x 45 mm wide with an average thickness of 4

mm for epoxy and 2mm for aluminium as shown in Fig. 3.17. The 90º notches were

formed at the centre of 60 mm length (at the top and bottom) such that the distance

between notches was left about 10 mm at the middle to introduce stress field on the

significant section, AB. 1.5 mm of notch radius was produced to minimise stress

concentration beside to produce a uniform shear stress distribution along the

significant section [7].

*All dimension in mm

Fig 3.1: The butterfly specimen geometry [7]

R1.5

26

3.1.2 Material Details

The epoxy namely Selfix Carbofibe adhesive, supplied by Exchem, United

Kingdom was used. The properties of Selfix Carbofibe adhesive were achieved by

blending/mixing a modified epoxy resin and inorganic fillers to form a base

component, which was activated by a thixotropic formulated amine hardener. This

epoxy adhesive consisted of two parts, namely; part A and part B (Fig. 3.1). Both

parts were mixed with a ratio of 3:1 as stated in the supplier‘s specification. Their

chemical formulations and cast properties are listed as in Table 3.1 and Table 3.2.

Material properties obtained from experiment conducted by Shukur. A. H [7] is

shown in Table 3.3.

Table 3.1: Chemical formulation of Selfix epoxy adhesive [7]

Materials Chemical formulation Colour

Part A (Epoxy)

Part B

(Hardener)

Contains 35 to 45% reaction

product of Epichorohydrin

Bisphenol A epoxide resin of

average molecular weight <

700

Contains 3,6,9,12-tetra-

azatetradecamethylenediamine

(<20%) and 4,4-

isopropylidenediphenol (<

10%)

White

Dark Grey

27

Table 3.2: Typical properties of Selfix Carbofibe epoxy adhesive [7]

Property Value

Compressive strength (MPa) aged of 7 days at 20 °C 90

Tensile strength (MPa) 23

Thermal expansion /°C 33 x 10-6

Shear modulus (GPa) na

Single lap shear strength (MPa) > 18

Glass transition temperature (DMTA) °C > 65

Water absorption 0.4%

(a) (b)

Fig. 3.2: Two parts of Selfix Carbofibe adhesive (a) Part A (b) Part B

Table 3.3: Material properties Selfix Carbofibe epoxy adhesive from Shukur. A. H

[7]

Specimen Ult. Load

(kN)

Shear

Modulus,

(GPa)

Shear

Strength,

(MPa)

Shear

strain, γ

(με)

Time to

failure

(sec)

Control* 1.43 2.97 29.24 9275 66.4

*Ref. Shukur. A. H [11]

The type of aluminium used for this project was 6061 as the selection of

isotropic ductile material. Material properties obtained from ASTM which refers to

standard specification for aluminium and aluminium-alloy sheet and plate.

28

Table 3.4: Mechanical properties of 6061 alloy [14]

Alloy Tensile

Strength, Mpa

Yield Strength,

Mpa Poisson ratio, v

6061 310 276 0.33

3.1.3 Mixing and Casting Process for Epoxy

The both of dumb-bell and butterfly shaped epoxy specimen were prepared

by mixing two parts of adhesive system consist of epoxy and hardener was mixed

with ratio of 3:1 (270 gram epoxy and 70 gram hardener). Then, both shapes of

specimens were produced by casting the mixtures onto a female mould.

A low speed electric mixer was then used to mix the materials until it turns

soft grey in colour as shown in Fig. 3.2. The mixing process was done in the

laboratory control room where the temperature and relative humidity was in range of

24°C to 26°C and 40% to 55% (i.e. by depending on the ambient laboratory

condition).

Fig 3.3: A mixing process using low speed electric mixer

Both shaped specimens were cast by using mild steel moulds which consisted

of male parts (top) and female parts (base). Before the specimens were casting, the

male and female mould surface were clean by using soft cloth and Canauba wax to

29

ensure the dirt remove away. Two flat plates were attached to cover the back part of

the mould by screws as shown in Fig. 3.3 (a) and (b). Then, the mixtures poured into

the female part mould as shown in Fig. 3.4 (a) and (b). This process was done

carefully to ensure minimum air trapped in the specimen.

(a) (b)

Fig 3.4: Flat plate attached to male part by screws

(a)Flat plate before installation (b) Flat plate after installation

(a) (b)

Fig. 3.5: Casting process by pouring the mixtures into the female mould

(a) Butterfly specimens (b) Dumbbell-shaped specimens

The male mould part was then attached to the female part and a metal block

weight of about 10 kg was placed onto the top of the mould to produce an extra

uniform pressure on the mould as shown in Fig 3.4(a) and (b). Finally the specimens

30

were left to solidify in a laboratory environment with temperature ranging from 23 to

33°C before demoulding process.

(a) (b)

Fig. 3.6: (a) Male part attached to the female part and (b) 10 kg mass used

Demoulding process of the specimens was carefully done by applying a soft

knocking force onto the butterfly shaped Teflon block using a wood hammer (Fig.

3.6). The Mecapol P255 U Polish Machine was used to make the surfaces of the

specimen smoother and the sharp edges rounder. The process is shown in Fig. 3.7 (a)

and (b).

Fig. 3.7: Demoulding process

31

(a) (b)

Fig. 3.8: Surface grinding and polishing process of the specimen

(a) Mecapol P255 U polishing machine (b) Manual polishing technique

Lastly, the specimens were checked for their final quality, established

(marked) the code name as shown in Fig. 3.8. Three specimens for each group of

samples were selected for the experimentation study of Arcan test method. Five

specimens for tensile test were selected for experimentation study of tensile test.

Fig. 3.9: Specimens ready for testing

The recorded data showed that the average specimen width, thickness and

cross sectional area of Arcan test method were in the range of 10.48 to 11.18 mm,

4.35 to 4.51 mm and 48.73 to 49.44 mm2 respectively for butterfly specimen, as

shown in Table 3.5.

32

Table 3.5: Butterfly specimen‘s width, thickness and significant area average

measurement

Sample Code Thickness(mm) Width(mm) Significant area

(mm2)

ES 4.48 10.75 48.16

ET 4.59 10.53 47.17

ETS 4.38 10.79 47.62

For dumbbell specimen, the recorded data showed that the average specimen

width, thickness and cross sectional area of Arcan test method were in the range of

10.48 to 11.18 mm, 4.35 to 4.51 mm and 48.73 to 49.44 mm2 respectively, as shown

in Table 3.6.

Table 3.6: Dumbbell specimen‘s width, thickness and significant area

average measurement


(mm2)

ST 3 13.15 39.45

3.1.3 Specimen Preparation for Aluminium

There were aluminium scraps with 2mm of thickness used for aluminium

specimen as shown in Fig. 3.9. All the specimens fabricated into 9 sample of

butterfly specimen using milling machine as shown in Fig.3.10(a) and (b)

33

Fig. 3.10: Aluminium scrap

(a) (b)

Fig. 3.11: (a) Milling machine (b) Specimen ready for labelling

.

The recorded data showed that the aluminium average specimen width,

thickness and cross sectional area of Arcan test method were in the range of 10.48 to

11.18 mm, 4.35 to 4.51 mm and 48.73 to 49.44 mm2 respectively, as shown in Table

3.5.

34

Table 3.7: Butterfly specimen‘s width, thickness and significant area average

measurement


(mm2)

AS 2.05 10.06 48.16

AT 2.05 10.33 47.17

ATS 2.04 10.04 47.62

3.1.5 Strain Gauge Installation

A rosette type strain gauge, TML FCA-1-11 with 1 mm gauge length was

installed onto the dumbbell specimen at the gauge section (Fig. 3.11). The gauge

bond surface in the significant area was prepared (roughened) with 1000 grade grain

size sand paper prior to cleaning by using liquid acetone to remove grease, dust or

dirt. Then, the strain gauge was attached onto the specimen in the direction of 0°

measured from the specimen‘s horizontal axis by referring to standard installation

procedure. The important parameters of the gauge specification are shown in Table

3.5.

Fig. 3.12: Strain gauge on dumbbell specimens

35

Table 3.8: Rossete type strain gauge specifications [15]

Manufacturer Tokyo Sokki Kenkyujo Co. Ltd. Japan

Gauge type TML FLA-1-17

Gauge factor 1 = 2.08, 2 = 2.08 1%

Coefficient of thermal expansion 11.8 x 10-6/°C

Tolerance ± 0.85 (μm/m)/°C

Temperature coefficient of gauge factor + 0.1 ± 0.05%/10°C

3.1.6 Tensile Test Set-Up and Test Procedure

Fig.3.12 showed the set-up of tensile test using dumbbell specimen. Both end

of specimen were attached to the loading machine. The tensile loads were applied

onto the specimen to produce tensile stress onto the specimen. The complete

measurement and instrumentation system is shown in Fig.3.13. It was equipped with

the following important features;

i. A load frame the dumbbell specimen was installed and loaded in tensile.

ii. A control panel that controlled the loading rate

iii. A computer for the user to key-in the properties and the information of the

specimen and set the format for the plotting of grapph and results.

iv. A data logger to record and print out the strain readings.

36

Fig. 3.13: Tensile test set-up

Fig. 3.14: Instrumentation set-up

3.7 Arcan Test Setup

The modified Arcan test fixture used in this study programme consisted of a

pair of male and female parts, as shown in Fig. 3.14. The butterfly specimen was

mounted into the female part followed by the male part. Both parts were tightened by

screws to ensure that the specimen was tightly gripped between the fixtures to

prevent from slippage and misalignment during loading. The complete assembly of

the fixtures was attached to the holder at the lower and upper parts accordingly prior

Cross Head

Load Cell

Instron Machine

Load Frame

Fixture Data Logger

37

to attachment to the Instron Universal Testing Machine, as shown in Fig. 3.15. The

Arcan fixture set-up at 0, 45, and 90 for tensile, tensile shear and shear loading

configuration respectively, as shown in Fig. 3.16 (a), (b), and (c)

Fig. 3.15: Arcan test fixture and butterfly specimen [7]

Fig. 3.16: Attached Arcan fixture to the holder

38

(a) (b) (c)

Fig. 3.17: Arcan fixture set-up configuration

(a)Tensile (b) Shear (c) Tensile shear

3.2 Specimen Modeling and Analysis Setup

The literature studies were carried out by sourcing the related information

from journals, handbooks, books, previous theses, and websites. Firstly, literature

review was carried out to understand the mechanical characteristic of the adhesive

system used in this study. Then, the studies focused on the Arcan test method in

order to investigate the theoretical background related to properties and to determine

related information on finite element analysis.

All the information and data about the material was obtained from ASTM and

experiment conducted by Shukur. A. H [7]. The modelling was divided into three

type of material which is epoxy and aluminium. Epoxy and aluminium was chosen to

investigate the characteristic of brittle and ductile isotropic material while carbon

fibre was chosen for brittle orthotropic material. The modelling and analysis was

carried out by using ANSYS in order to investigate the stress characteristic and

response of the butterfly specimen. The load and boundary condition were applied to

the specimen modelling to perform exact condition of Arcan test method experiment.

Data were gathered from the result that was established during analysis finite

element analysis. The contour of critical area was observed in order to investigate the

factor and location that influent the data.

39

3.2.1 Specimen Modeling

The specimen was model using ANSYS WORKBENCH as shown in

Fig.3.18. The thickness of modeled specimen was referred to the type of material as

discussed before.

Fig.3.18: Butterfly specimen of epoxy in ANSYS

3.2.2 Input Material Data

All the gathered data was enter to the ANSYS table for finite element

analysis as shown in Fig. 3.19.

40

Fig. 3.19: Material properties table in ANSYS

3.2.3 Meshing

A simple mesh was used to represent the element of adhesive material in the

test section. Fig. 3.20 shows the mesh used for all specimens modelling. Multiple

elements were used to model the test section even though a single element would

have been sufficient to approximate the nature of the Arcan test. Fine element with

size of 1mm was used to provide accurate analysis in the significant section.

Fig. 3.20: Meshed model specimen

41

3.2.4 Boundary Condition and Loading Setup

Based on literature study, the boundary condition and load direction proposed

by R. Rinaldi [10] was used to for finite element analysis. The load applied to the

specimen in which direction of loading configuration discussed before. The boundary

condition and loading setup for shear, tensile shear and tensile of butterfly model in

ANSYS is shown in Fig. 3.21 (a), (b), and (c).

Fig 3.21: Boundary condition and loading setup

(a) Shear (b) Tensile shear (c) Tensile

3.3 Summary

In this chapter, the explanations from specimen preparations until the

experimentation and test set up were briefly discussed. For the specimen

preparations, discussions focused on the materials, specimen geometry, process to

produce specimens and finite element analysis. Then for the experimentation and test

set-up, the discussion based on the Arcan rig installation, specimen testing

procedure, and data analysis from the tested experimentation. The testing procedure

must be followed strictly in order to obtain reliable data.

42

CHAPTER 4

RESULTS AND DISCUSSION

4.0 Introduction

In this chapter, the discussion was focused onto the characteristic of different

loading configuration onto the aluminium and epoxy system by discussing the result

of the Arcan test method and finite element analysis. The result were analysed and

presented in term of graphs and table established a comprehensive technical

discussion. The result discussion was based one specimen of each loading

configuration of test sample with final conclusion will be focused on the average

performance result between experimental and finite element analysis. Then, the

performance of tensile test result from Arcan test method will be evaluate by

comparing the data with the common tensile test method using dog bone specimen.

43

4.1 Sample Testing Evaluation

The result and discussion were focus on the experiment data analysis and

finite element analysis of butterfly specimen. The determination of characteristic of

Selfix Carbofibe adhesive and aluminium specimens due to different loading

configuration through Arcan test method was the main parameter discussed. The

result were analysed and presented in term of graphs, tables, and figures in order to

provide a more comprehensive technical discussion. Overall, the discussion was

referred to a selected significant specimen from each group of test sample. The

overall discussion also covered the uniformity of stress based on notch radius and the

performance of tensile result from Arcan test method compare to common tensile test

using dumbbell specimen through finite element analysis.

4.1.1 Test Rig-Specimen Evaluation of Tensile Method for Epoxy

From load test, it could be observed that all epoxy specimens fail in the brittle

form. The fracture line occurs at 90° angle measured from the direction of load as

shown in Fig. 4.7. This situation confirmed that the specimen failed in the direction

of principal stresses which was the direction of the tensile principle stress

corresponding to the state of pure tensile.

Fig. 4.1: Brittle failure of ST1 epoxy

44

Therefore, the maximum load applied to all specimens before fracture are

recorded for finite element analysis. Finally, by assuming the stress distribution

along significant section AB was uniform, the following calculation was done in

order to evaluate the alignment of specimen stress element. A sample calculation was

done for specimen ST1 as follow;

Specimen thickness, t = 2.73mm,

Specimen significant section, AB = 13mm

Load carried by specimen at load, F= 100N

Specimen cross section area, A = t x h mm2

The average tensile stress can determine as follow;

From equation, the average shear stress is:

4.1.2 Test Rig-Specimen Evaluation for Arcan Test Method

From load test, it could be observed that different type of fracture occur are

based on direction of loading configuration. All epoxy and aluminium specimens fail

in the form of brittle and ductile behaviour respectively. Therefore, the maximum

load applied to all specimens before fracture are recorded for finite element analysis.

45

4.1.2.1 Shear Test for Epoxy and Aluminium Sample

From load test, it could observe that the fracture line of epoxy specimen

occurred at about 45° angle measured from the specimen principal axis to the line of

significant section AB as shown in Fig. 4.2. This situation confirmed that the

specimen failed in the direction of principal stresses which was the direction of the

tensile principle stress corresponding to the state of pure shear.

Fig. 4.2 Brittle failure of ES1 occurred at 45°

Finally, by assuming the stress distribution along significant section AB was

uniform, the following calculation was done in order to evaluate the alignment of

specimen stress element. A sample calculation was done for specimen ES1 as follow;


Specimen significant section, AB = 10.6mm



The average shear stress can determine as follow;


46

From load test, it could observe that the fracture line of AS2 specimen


significant section AB as shown in Fig 4.3. This situation confirmed that the

specimen failed in the direction of shear stress which was the direction of stress

corresponding to the state of pure shear. It also can be confirmed that shear strength

of aluminium are low compare to tensile strength.

Fig. 4.3: Ductile failure of AS1specimen occurred at 90°



specimen stress element. A sample calculation was done for specimen AS1 as

follow;





The average shear stress and shear strain can determine as follow;


47

4.1.2.2 Tensile Test for Epoxy and Aluminium Sample

From load test, it could observe that the fracture line of ET2 specimen




tensile principle stress corresponding to the state of pure tensile.

Fig. 4.4: Brittle failure of ET2 specimen occurred at ±90°



specimen stress element. A sample calculation was done for specimen ET1 as follow;






From equation, the average normal stress is:

48

From load test, it could observe that the fracture line of AT1 specimen



specimen failed in the direction of principle stress which was the direction of shear

principle stress corresponding to the state of pure shear. It also can be confirmed that

shear strength of aluminium are low compare to tensile strength.

Fig. 4.5: Ductile failure of AT occurred at ±45°



specimen stress element. A sample calculation was done for specimen S1 as follow;






From equation, the average normal stress is:

49

4.2.2.3 Tensile Shear Test for Epoxy and Aluminium Sample

From load test, it could observe that the fracture line of ETS3 specimen




tensile principle stress corresponding to combination tensile and shear loading.

Fig. 4.6: Brittle failure of ETS3occurred at ±30°



specimen stress element. A sample calculation was done for specimen ETS1 as

follow;







50

From load test, it could observe that the fracture line of ATS2 specimen



specimen failed in the direction of shear stress although the direction of tensile

principle stress is about 30° from principle axis. It also can be confirmed that shear

strength of aluminium are low compare to tensile strength.

Fig. 4.7: Ductile failure of ATS2Aluminium occurred at ±90°



specimen stress element. A sample calculation was done for specimen ATS1 as

follow;







51

4.2 Experimental Result for Arcan Test Method

4.2.1 Experimental Results for Shear Loading of Epoxy

There were three (3) specimens for the epoxy sample. All specimens, ES1 to

ES3 have shown brittle characteristics of failure, which occurred at 45° from the

specimen‘s principal axis, and the complete test data for the epoxy sample, which

was calculated from previously stated equations, are shown in Table 4.3.

Table 4.1: Shear test data for ES samples

Sample Ultimate Load

(kN)

Cross Sectional Area

(m2)

Shear Strength

(MPa)

ES1 1.037 4.84x10-5

21.43

ES2 1.006 4.76x10-5

21.13

ES3 1.109 4.85x10-5

22.87

Average 1.051 4.82x10-5

21.81

(0.93)

Note: The value listed in bracket represent the standard deviation

From Table 4.3, it can be seen that the highest of ultimate failure load was 1.1

kN and the lowest ultimate load was 1.006 kN. The average ultimate failure loading

for this sample was 1.051kN. The value of average shear stress obtain from

experiment was 21.81 MPa (i.e. about 4.3% of specimens data value deviated from

their average value). From manufacturer specification, the shear strength for Selfix

Carbofibre adhesive was higher than 18 MPa (i.e under shear lap shear test method).

By comparing shear strength with experiment conducted by Shukur A. H [8], the

value obtained was 17.43% higher.

52

4.3.2 Experimental Results for Shear loading of Aluminium

There were three (3) specimens for the aluminium sample. All specimens,

AS1 to AS3 have shown ductility characteristics of failure, which occurred at 90°

from the specimen‘s principal axis due to low shear strength. The complete test data

for the aluminium sample, which was calculated from previously stated equations,

are shown in Table 4.2.

Table 4.2: Shear test data for ES samples

Sample Ultimate Load

(kN)

Cross Sectional Area

(m2)

Shear Strength

(MPa)

AS1 4.45 2.07x10-5

215.12

AS2 4.47 2.05x10-5

218.1

AS3 4.54 2.07x10-5

219.37

Average 4.49 2.06x10-5

217.53

(2.18)


From Table 4.4, it can be seen that the highest of ultimate failure load was

4.54 kN and the lowest ultimate load was 4.45 kN. The average ultimate failure

loading for this sample was 4.488 kN. The value of average normal stress obtain

from experiment was 217.53 MPa (i.e. about 1% of specimens data value deviated

from their average value).

.

4.3.3 Experimental Results for Tensile Loading of Epoxy

There were three (3) specimens for the epoxy sample. All specimens, ET1 to

ET3 have shown brittle characteristics of failure, which occurred at 90° from the



53

Table 4.3: Tensile test data for TS samples

Sample Ult. Load (kN) Cross Sectional Area(m2) Tensile Strength (MPa)

ET1 0.827 4.85x10-5

17.05

ET2 0.913 4.89x10-5

18.67

ET3 0.918 4.79x10-5

19.16

Average 0.886 4.82x10-5

18.29

(1.1)



0.918kN and the lowest ultimate load was 0.827 kN. The average ultimate failure

loading for this sample was 0.886kN. The value of average normal stress obtain from

experiment was 18.29 MPa (i.e. about 6% of specimens data value deviated from

their average value).

4.3.4 Experimental Results for Tensile Loading of Aluminium

There were three (3) specimens for the aluminium sample. All specimens,

AT1 to AT3 have shown ductile characteristics of failure, which occurred at 45°

from the specimen‘s principal axis, and the complete test data for the aluminium

sample, which was calculated from previously stated equations, are shown in Table

54

Table 4.4: Tensile test data for AT samples

Sample Ult. Load (kN) Cross Sectional Area(m2) Tensile Strength (MPa)

AT1 6.6 2.03x10-5

325.07

AT2 6.52 2.27x10-5

287.31

AT3 6.71 2.26x10-5

296.77

Average 6.61 2.19x10-5

303.05

(19.65)



6.71N and the lowest ultimate load was 6.52kN. The average ultimate failure loading

for this sample was 6.61kN. The value of average normal stress obtain from



4.3.5 Experimental Results for Tensile Shear Loading of Epoxy

There were three (3) specimens for the epoxy sample. All specimens, ETS1

to ETS3 have shown brittle characteristics of failure, which occurred at 30° from the


was calculated from previously stated equations, are shown in Table

4.7.

55

Table 4.5: Tensile Shear test data for ETS samples

Sample Ult. Load (kN) Cross Sectional Area(m2) Shear Strenght (MPa)

ETS1 0.74 4.77x10-5

15.43

ETS2 0.81 4.61x10-5

17.53

ETS3 0.81 4.77x10-5

16.87

Average 0.78 4.72x10-5

16.61

(1.07)


From table, it can be seen that the highest of ultimate failure load was 0.81kN

and the lowest ultimate load was 0.74kN. The average ultimate failure loading for

this sample was 0.78kN. The value of average normal stress obtain from experiment

was 16.61 MPa (i.e. about 6.4% of specimens data value deviated from their average

value).

4.3.6 Experimental Results for Tensile Shear loading of Aluminium

There were three (3) specimens for the epoxy sample. All specimens, ATS1

to ATS3 have shown brittle characteristics of failure, which occurred at 90° from the



56

Table 4.6: Tensile Shear test data for ATS samples

Sample Ult. Load (kN) Cross Sectional Area(m2) Shear Strenght (MPa)

ATS1 5.57 2x10-5

278.45

ATS2 5.63 2.07x10-5

272.03

ATS3 5.54 2.08x10-5

266.25

Average 5.58 2.05 x10-5

272.24

(6.1)



5.57kN and the lowest ultimate load was 5.54kN. The average ultimate failure

loading for this sample was 5.58kN. The value of average normal stress obtain from



4.3 Experimental Result for Tensile Test

4.3.1 Experimental Data of Tensile Test Method for Epoxy

There were three (5) specimens for epoxy sample. All specimens, ST1 to ST5

have shown brittle characteristics of failure, which occurred at 90° from the

specimen‘s principal axis. The raw data for ST1 specimen are shown in Table 4.9

and the complete test data sample, which was calculated from previously stated

equations, are shown in Table 4.10.

57

Table 4.7: Experiment data for ST1 sample

P(kN) σ(MPa) ey1(µmm) ey2(µmm) ey(µmm) E(GPa) ey(m)

0.1 2.87 498 486 492 5.82 0.000492

0.2 5.73 741 717 729 7.86 0.000729

0.3 8.60 1043 1010 1026.5 8.37 0.001027

0.4 11.5 1388 1349 1368.5 8.37 0.001369

0.5 14.3 1641 1598 1619.5 8.85 0.00162

0.6 17.2 2092 2036 2064 8.33 0.002064

0.7 20.1 2478 2407 2442.5 8.21 0.002443

0.8 22.9 2884 2794 2839 8.07 0.002839

0.9 25.8 3374 3253 3313.5 7.78 0.003314

1.0 28.7 3928 3781 3854.5 7.43 0.003855

Table 4.8: Test results for ST samples

Sample Ult. Loading

(kN)

Strain near

failure

Tensile

modulus (Gpa)

Tensile

strength (MPa)

ST1 0.90 0.0033915 7.43 25.4

ST2 1.10 0.003491 8.56 29.9

ST3 1.00 0.0038545 7.78 28.7

ST4 0.9 0.003757 7.68 27.7

ST5 1.1 0.003702 7.54 26.7

Average 1.00 0.003692 7.79

(0.45)

27.7

(1.74)


From table 4.10, it can be seen that the highest ultimate failure load was 1.10

kN and the lowest was 0.9 kN. The average for ultimate load was 1kN. The average

tensile modulus and tensile strength are 7. (i.e. about 6% of specimens data value

deviated from their average value) and 2.77 MPa (i.e. about 6.3% of specimens data

value deviated from their average value), respectively. By comparing to

manufacturer specification, the tensile strength for Selfix Carbofibre was 17% higher

than the minimum manufacturer quoted value.

58

The normal stress and normal strain data in Table 4.9 were used in plotting

the normal stress versus normal strain curve as shown in Figure 4.8. The stress-strain

curve shows that strain on each specimen was linearly propagated.

Fig. 4.8: Stress-strain curve for ST1 sample

4.4 Finite Element Analysis

From finite element analysis, it can be observed that different characteristic

of stress in field based on different type of loading configuration. The stress

distribution was found concentrated at the significant AB section of specimen. This

scenario satisfies with theoretical analysis which means high stress developed due to

small cross sectional area. Therefore, maximum stress and strain from finite element

analysis are obtained which refer to average maximum load from experiment.

59

4.4.1 Finite Element Analysis Result for Shear Loading of Epoxy

A load step of 100N was applied to the modelled specimen until it reach

ultimate loading. All the data gathered from the gauge section as shown in Table

4.11.

Table 4.9: Analysis result for shear loading of Selfix Carbofibre epoxy

Load (kN) Shear Stress (MPa) Shear Strain, xy Normal strain, x

0.1 2.303 7.7543e-004 -1.789e-005

0.2 4.6061 1.5509e-003 -3.578e-005

0.3 6.9091 2.3263e-003 -5.367e-005

0.4 9.2122 3.1017e-003 -7.156e-005

0.5 11.515 3.8772e-003 -8.945e-005

0.6 13.818 4.6526e-003 -1.0734e-004

0.7 16.121 5.428e-003 -1.2523e-004

0.8 18.424 6.2035e-003 -1.4312e-004

0.9 20.727 6.9789e-003 -1.6101e-004

1.0 23.03 7.7543e-003 -1.789e-004

1.051 24.205 8.1498e-003 -1.8802e-004

From Table 4.11, it can be seen that maximum stress generated at the gauge

section about 24.437 Mpa, which also indicate as shear strength. As compared to the

experimental data, the shear stress was found 10.75% higher. The maximum shear

strain is 8255µε when ultimate load were applied. The existence of normal strain

shows that Arcan test method was not perfectly producing shear stress. Meanwhile,

normal strains generated are too small and can be neglect.

The stress and strain data were used in plotting the stress versus strain curve

as shown in Fig. 4.10. The stress-strain curve show that strain was linearly

propagated. From the curve, it can shear modulus of material was found about

29.7GPa which indicate the gradient of the curve. By comparing to experiment

conducted by shukur[8], the value of shear modulus from finite element method was

60

almost similar. This means that Arcan test methods proven by finite element analysis

in order to measure shear modulus of material.

Fig 4.9: Shear stress-strain curve of Selfix Carbofibre epoxy

From experiment, the epoxy specimens failed in direction of tensile principle

stress when ultimate load about 1015N are applied to the specimen. Therefore, finite

element analysis on the maximum principle stress, maximum shear stress and

maximum shear strain regarding to the ultimate shear loading condition are shown in

Fig 4.10(a), 4.10(b) and 4.10(c) respectively

(c)

Fig. 4.10: (a) Maximum principal stress (b) Maximum shear stress (c) Equivalent

elastic strain

By observing the stress field on the modelled specimen, the maximum

principle stress about 64.97Mpa was located at the notch of the significant section

AB. The stress field also show almost similar shape of fracture line specimen that

61

can be seen during experiment. The maximum shear stress about 32.58Mpa located

at the notch. The maximum shear strain about 7776µ located at the notch of gauge

section. Both situations clearly describe that the fracture initiated at the notch of the

significant section AB.

The linearized stress data were used in plotting uniformity of stress along the

significant section AB as shown in Fig.4.11. The stress was found uniform at the

middle and high at the both end. This confirmed that the state of ―pure shear‖ stress

was form regarding to the direction of load applied. The high stress located at the

both end of significant section is due to effect of notch which generated stress

concentration.

Fig. 4.11: Stress distribution along significant section AB of Selfixe Carbofibre

epoxy due to shear loading

4.4.2 Finite Element Analysis Result for Shear Loading of Aluminium



4.12.

62

Table 4.10: Analysis result for shear loading aluminium

Load (kN) Shear Stress (Mpa) Shear Strain, xy Normal strain, x

0.5 22.791 8.7657e-004 2.1625e-005

1.0 45.582 1.7531e-003 4.325e-005

1.5 68.372 2.6297e-003 6.4875e-005

2.0 91.163 3.5063e-003 8.6501e-005

2.5 113.95 4.3828e-003 1.0813e-004

3.0 136.74 5.2594e-003 1.2975e-004

3.5 159.54 6.136e-003 1.5138e-004

4.0 182.33 7.0125e-003 1.73e-004

4.49 204.6 7.8693e-003 1.9414e-004

From Table 4.12, it can be seen that maximum stress generated at the gauge

section about 204.6 Mpa, which also indicate as maximum shear stress. The

maximum shear strain was 7869.3µ when ultimate load applied.


as shown in Fig.4.12. The stress-strain curve show that strain was linearly

propagated. From the curve, it can shear modulus of material was found about 26GPa

which indicate the gradient of the curve. By comparing to ASTM [22], the value of

shear modulus from finite element method was almost similar. This means that finite

element analysis prove that Arcan test methods are suitable to measure shear

modulus of material.

Fig. 4.12: Shear stress-strain curve for aluminium

63


stress when ultimate load about 4488.7N are applied to the specimen. Therefore,

finite element analysis on the maximum principle stress, maximum shear stress and



(c)

Fig. 4.13: (a) Maximum principal stress (b) Maximum shear stress (c) Equivalent

elastic strain

By observing the stress field on the modeled specimen, the maximum

principle stress about 505.8Mpa was located at the notch of the significant section

AB. The stress field also show almost similar shape of fracture line specimen that

can be seen during experiment. The maximum shear stress about 253.63MPa located

at the notch. The maximum shear strain about 0.009412µ also located at the notch of

gauge section. Both situations clearly describe that the fracture initiated at the notch

of the significant section AB.


significant section AB as shown in Fig. 4.14. The stress was found uniform at the

middle and high at the both end. This confirmed that the state of ―pure shear‖ stress

was form regarding to the direction of load applied. The high stress located at the

both end of significant section is due to effect of notch which generated stress

concentration.

64

Fig. 4.14: Stress distribution along significant section AB of aluminium due to shear

loading

4.4.3 Finite Element Analysis Result for Tensile Loading of Epoxy



4.13.

Table 4.11: Analysis result for tensile loading of Selfix Carbofibre epoxy

Load (kN) Normal Stress (MPa) Normal strain, µx

0.1 1.5702 162.03

0.2 3.1404 324.06

0.3 4.7107 486.08

0.4 6.2809 648.11

0.5 7.8511 810.14

0.6 9.4213 972.17

0.7 10.992 1134.2

0.8 12.562 1296.2

0.89 13.923 1436.7

65

From table, it can be seen that maximum stress generated at the gauge section

about 24.437 Mpa, which also indicate as shear strength. The maximum shear strain

was 1436.7µε when ultimate load applied.




96.97GPa which indicate the gradient of the curve.

Fig. 4.15: Stress-strain curve for epoxy






Fig. 4.16: (a) Maximum principal stress (b) Maximum normal stress (c) Equivalent

elastic strain

66

By observing the stress field on the modeled specimen, the maximum

principle stress about 52.4Mpa was located at the notch of the significant section AB.

The maximum normal stress about 48.76Mpa located at the notch. The maximum

shear strain about 5850µ also located at the notch of gauge section. Both situations

clearly describe that the fracture initiated at the notch of the significant section AB.


significant section AB as shown in Fig.4.17. The stress was found uniform at the

middle and high at the both end. This confirmed that the state of tensile stress was

form regarding to the direction of load applied. The high stress located at the both

end of significant section is due to effect of notch which generated stress

concentration.

Fig. 4.17: Stress distribution along significant section AB of Selfix Carbofibre epoxy

due to tensile.

4.4.4 Finite Element Analysis Result for Tensile Loading of Aluminium


ultimate loading. All the data gathered from the gauge section as shown in Table 4.1.

67

Table 4.12: Analysis result for tensile loading of Aluminium

Load (kN) Normal Stress (Mpa) Normal strain, µx

1.0 31.606 368.79

2.0 63.212 737.58

3.0 94.818 1106.4

4.0 126.42 1475.2

5.0 158.03 1844

6.0 189.64 2212.8

6.6 208.91 2437.7

From table, it can be seen that maximum normal stress generated at the gauge

section about 208.91 Mpa. The maximum shear strain is 2437µ when ultimate load

were applied.




85.7GPa which indicate the gradient of the curve.

Fig. 4.18: Stress-strain curve for aluminium




68


Fig 4.19(a), and 4.20(c) respectively.

Fig. 4.19: (a) Maximum principal stress (b) Maximum normal stress (c) Equivalent

elastic strain


principle stress about 787Mpa was located at the notch of the significant section AB.

The maximum normal stress about 731Mpa located at the notch. The maximum

normal strain about 10142µ also located at the notch of gauge section. Both

situations clearly describe that the fracture initiated at the notch of the significant

section AB.


significant section AB as shown in Fig. 4.20. The stress was found uniform at the

middle and high at the both end. This confirmed that the state of tensile stress was

form regarding to the direction of load applied. The high stress located at the both

end of significant section is due to effect of notch which generated stress

concentration.

69

Fig. 4.20: Stress distribution along significant section AB of aluminium due to

tensile.

4.4.5 Finite Element Analysis Result for Tensile Shear Loading of Epoxy



4.15.

Table 4.13: Analysis result for tensile Shear Loading of Selfix Carbofibre epoxy

Load Y Direction

(kN)

Load X Direction

(kN)

Magnitude

(N)

Principle Stress

(Mpa)

0.1 0.1 0.141 3.576

0.2 0.2 0.283 7.1521

0.3 0.3 0.424 10.728

0.4 0.4 0.566 14.304

0.5 0.5 0.707 17.88

0.522 0.522 0.739 18.684

From table, it can be seen that maximum principle stress generated at the

gauge section about 18.684Mpa.

70


stress when ultimate load about 738.9N are applied to the specimen. Therefore, finite

element analysis on the maximum principle stress is shown in Fig 4.21.

Fig. 4.21: (a) Maximum principal stress


principle stress about 326Mpa was located at the notch of the significant section AB.

This situation clearly describe that the fracture initiated at the notch of the significant

section AB. In addition, the high stress generated due to existence of bending

moment.


significant section AB as shown in Fig. 4.22. The stress was found concentrated only

at one end of significant section AB. This situation can be considered that the stress

generated due to bending. The high stress located at the both end of significant

section is due to effect of notch which generated stress concentration.

71


tensile shear load.

4.4.6 Finite Element Analysis Result for Tensile Shear Loading of Aluminium



4.16.

Table 4.14: Analysis result for tensile shear loading of aluminium

Load y direction

(kN)

Load x direction

(kN)

Magnitude

(kN)

Principle Stress

(Mpa)

0.5 0.5 0.707 35.508

1.0 1.0 1.414 71.016

1.5 1.5 2.121 106.52

2.0 2.0 2.828 142.03

2.5 2.5 3.535 177.54

3.0 3.0 4.141 213.05

3.5 3.5 4.949 248.56

3.85 3.85 5.579 275.72

72

From table, it can be seen that maximum stress generated at the gauge section

about 275.71Mpa, which also indicate as shear strength.

From experiment, the aluminium specimens failed in direction of tensile

principle stress when ultimate load about 5579N are applied to the specimen.

Therefore, finite element analysis on the maximum principle stress regarding to the

ultimate tensile shear loading condition are shown in Fig 4.23.

Fig. 4.23: (a) Maximum principal stress


principle stress about 4813Mpa was located at the notch of the significant section

AB. This situation clearly describe that the fracture initiated at the notch of the

significant section AB. In addition, the high stress generated due to existence of

bending moment.


significant section AB as shown in Fig. 4.24. The stress was found concentrated only

at one end of significant section AB. This situation can be considered that the stress

generated due to bending. The high stress located at the both end of significant

section is due to effect of notch which generated stress concentration.

73


tensile shear load.

4.5 Notch Sensitivity Analysis

From finite element analysis, it can be seen that stress concentration take

place at the notch of significant section AB. There were three notch radii selected to

determine most appropriate radius of 1.5mm, 2.5mm, and 3.5mm. Both Selfix

Carbofibre and aluminium with brittle and ductile behaviour respectively, were used

in this analysis to identify the effect on notch radius. The linearized stress data were

used in plotting neutralized stress with different notch radius along the significant

section AB as shown in Fig. 4.25, Fig. 4.26, Fig. 4.27, and Fig 4.28.

74

Fig. 4.25: Effect of notch on stress distribution of Selfix Carbofibre due to shear

load.

From Fig 4.26, the effect of notch was found higher when 1.5mm radius on

Selfix Carbofibre epoxy, which resulting about 20% high of stress than average value

1. The notch effect reduced as an increase of notch radius. Therefore, the most

optimum notch was 3.5mm as it provides most uniform stress along significant

section AB.

Fig. 4.26: Effect of notch on stress distribution of Selfix Carbofibre due to tensile

load.

From Fig. 4.27, it can be seen that the effect of notch to tensile stress of

Selfix Carbofibre epoxy reduce as increase of notch radius. Therefore, the uniformity

of stress can be improved by increasing the notch radius until it reaches optimum

value.

75

Fig. 4.27: Effect of notch on stress distribution of aluminium due to shear load.

From Fig. 4.25, the effect of notch was found higher when 1.5mm radius on

Aluminium, which resulting about 5% high of stress than average value 1. Therefore,

the most optimum notch was found between 2.5mm and 3.5mm as it provides most

uniform stress along significant section AB.

Fig. 4.28: Effect of notch on stress distribution of aluminium due to tensile load.

From Fig 4.26, it can be seen that the effect of notch to tensile stress of

Aluminium reduce as increase of notch radius. Therefore, the uniformity of stress

can be improved by increasing the notch radius until it reaches optimum value.

76

4.6 Tensile Test Performance Analysis

According to Arcan et.al, tensile stress can be produce to the butterfly

specimen when applying load at α=0°. In order to measure the performance of tensile

data of both materials, ASTM data of each material was introduced in the analysis as

the reference. Two selection of notch radius of 2.5mm and 3.5mm from Arcan

method was made to identify the notch effect on tensile data. The stress versus strain

data of Selfix Carfibre epoxy and aluminium were used in plotting stress versus

strain curve as show Fig. 4.29 and Fig. 4.30 respectively.

Fig. 4.29: Stress-strain curve of Selfix Carbofibre epoxy with different notch radius.

Fig. 4.30: Stress-strain curve of aluminium with different notch radius.

77

From both Fig.4.29 and Fig. 4.30, it can be seen the gradient of each curve

indicate the tensile modulus of the material. The tensile modulus of both materials

from ASTM was found almost the same with experimental data. By comparing both

notches of Arcan test method with ASTM data, it was found that 1.5mm of notch

radius showing large percentage of difference. This means that notch effect take

place in the performance of tensile data of Arcan test method. Based on the data, the

performance of tensile data can be improved by increasing notch radius.

78

CHAPTER 5

CONCLUSION AND RECOMMENDATION

5.0 Conclusion

The major conclusions that can be made from this study are summarised as

follows;

i. The study objective to finite element modelling of the butterfly

specimen was achieved. The significant section of butterfly specimen

has proven that Arcan test was reliable, as the shear stress and strain

relationship was linearly propagated. The existences of normal strain

indicate that pure shear loading are not perfectly produce by Arcan

test. But the result can be accepted since the value was too small.

ii. The stress distribution through specimen body can be observed. The

location of maximum stress and maximum strain can be determined

where the failure and fracture initiate.

iii. The uniformity of stress along significant section AB affected by

notch. A notch with 1.5mm radius still not sufficient to overcome

79

stress concentration especially for brittle and ductile material. For

shear test epoxy, the optimum radius was 3.5mm. For shear test of

aluminium, the optimum radius was between 2.5mm and 3.5mm.

iv. The tensile test from Arcan test method capable to perform reliable

tensile data. The present of notch affected the performance of tensile

test.

v. The performance of improve as increasing the notch radius in order to

reduce stress concentration.

5.1 Recommendation

Some of the recommendation will be suggested here in order to obtain a

better test result in the future;

i. The designs of the butterfly mould need to be modified to reduce

stress concentration effect especially at the notch area of butterfly

specimen.

ii. A number of specimens have to be increased in order to obtain

consistent data for accurate result.

iii. Modification on butterfly specimen design for tensile test by

introducing gauge location.

80

REFERENCES

1. Ashok D. B and Tirupathi R. C Introduction to Finite Elements in

Engineering. Fourth Edition, Pearson International, Inc., 2012, pp. 17

2. Arcan, M., Hashin, Z. and Voloshin, A. A Method to Produce Uniform Plane-

Stress States with Applications to Fibre-Reinforced Materials. Experimental

Techniques, April 1978, pp. 141-146

3. L. J. Taylor, Effective Use of Epoxy And Polyester Resins in Civil

Engineering Structure: CIRIA REPORT

4. Maalej, M, Goh, W. H. and Paramasivan, P. Analysis and Design of FRP

Externally-Reinforced Concrete Beams against Debonding-type Failures.

Materials and Structures/Materiaux et Constructions, Vol. 34, August-

September 2001

5. Arcan, M. A. New Method for Analyzing of Mechanical Properties of

Composites Materials. 3rd International Congress on Experimental

Mechanics, Los Angeles, California, 1973

6. Yen, S.C., Craddock J.N. and Teh, K.T. Evaluation of a Modified Arcan

Fixture for In-Plane Shear Test of Materials. Experimental Techniques,

December, 1988

7. Shukur, A.H., Mechanical Performance of Carbon Fibre Reinforced Vinyl

Ester Composite Plate Bonded Concrete Exposed to Tropical Climate. PhD

Thesis, UTM, 2007

8. Rani El-Hajjar and Rami Haj-Ali. In Plane Shear Testing of Thick Pultruded

FRP Composites using Modified Arcan Fixture. Composites Part B, Volume

(35):2004, pp. 421-428

81

Shigley, J. E., Mishchke, C.R and Budynas, R.G. Mechanical Engineering

Design. 7th

edition, 2003, pp.24

9. Samuel. B. and Bertrand. L. Arcan test and strain field measurement to study

material properties behaviour in 6056T78 FSW specimens, 6th

International

FSW Symposium, Saint-Sauveur, Canada. 10-13 October 2006

10. R. Rinaldi, Modelling of the mechanical behaviour of amorphous glassy

polymer based on the quasi-point defect theory—Part II:3D formulation and

finite element modelling of polycarbonate , December 2010

11. David DELSART and Jean Michel MORTIER, Identification of the Interface

Properties of Fibre Reinforced Composite Materials, June 2008

12. International, ASTM. (2014). Standard Test Method forTensile Properties of

Plastics. Designation: D638 − 10.

13. Shadlou, S. (2104). The effect of strain-rate on the tensile and compressive

behavior. Materials and Design.

14. Gall, H. E. (1985). Metals Handbook. American Society for Metals.

15. Kenkyujo, T. S. (2014). Foil Strain Gauge. Tokyo: Tokyo Sokki Kenkyujo.

82

APPENDIX

Fig. A1 Type and dimension of Dumbbell shape specimen

Fig. A2 Engineering drawing of epoxy adhesive butterfly specimen mould

83

Fig. A3 Engineering drawing of modified Arcan shear test fixture

universiti teknologi malaysia · 2017. 8. 8. · utm(fkm)-1/02 faculty of mechanical engineering...

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