UNIVERSITI PUTRA MALAYSIA
CRUSHING BEHAVIOR OF HEXAGONAL COMPOSITE TUBES
MUNIR FARAJ M. ALKABIR.
FK 2004 38
CRUSHING BEHAVIOR OF HEXAGONAL COMPOSITE TUBES
BY MUNIR FARAJ M. ALKABIR
Thesis Submitted to the School of Graduate Studies, Universiti Putra Malaysia, in Fulfilment of the Partial Requirements for the Degree of Master of Science
March 2004
DEDICATION
This work is dedicated
To my family
Parents brothers sister and to my wife and daughter
Abstract of thesis presented to the Senate of Universiti Putra Malaysia in partial fulfillment of the partial requirements for the degree of Master of Science
CRUSHING BEHAVIOR OF HEXAGONAL COMPOSITE TUBES
BY MUNIR FARAJ M. ALKABIR March 2004 Chairman:
Associate Professor Abdel Magid Salem Hamouda, Ph.D.
Faculty:
Engineering
An experimental and finite element analysis was carried out to investigate effect of hexagonal composite tube dimension on failure mode and energy absorption capability. Throughout this investigation, the hexagonal tube with different aspect ratio of length to thickness (Llt) varying from 30 to 100 and different hexagonal angles varying from 35" to 60" in 5" increments were investigated under the axial load condition. All the hexagonal tubes tested were fabricated from fabric plain weave /epoxy.
The effect of hexagonal geometry on the load carrying capacity and energy absorption capability was presented. A finite element model to predict the load carrying capacity, deformation mesh, stress contours at pre-crush stage of hexagonal tube under an axial load condition were developed.
Experimental results show that the hexagonal geometry (length to side diminutions) increases the load carrying capacity by 32.0, 13.8, 2.land 18.7% respectively for hexagonal side angle of 35", 45", 50°, and 55" respectively, the load carrying capacity is reduce by 49.6 and 29.6% for hexagonal side angles of 4O0and 6O0repectively. The energy absorption also increases by 1.42 and 1.5 % for hexagonal side angles of 35" and 6O0respectivelyand energy absorption is reduced by 48.6, 11.6, 20.0and 46,7% respectively for hexagonal side angle of 40°, 45", 50" and 55" respectively. Finite element model predictions are correlated with experimental results. The variation between the experimental and finite element is in the range of 5.9%to 9.8%.The effect of geometry of fabric plain weavelepoxy (Ring Chain System With Hexagonal Shape) on crushing behavior, energy absorption capability, crush failure loads and failure modes were also investigated.
Failure modes were examined using several photographs taken during the crushing stages for each experiment. The main failures modes that occured during the experiment are local buckling, catastrophic and matrix failure modes.
Abstrak tesis yang dikemukakan kepada Senat Universiti Putra Malaysia sebagai memenuhi keperluan untuk ijazah Master Sains
KELAKUAN PENGHANCURAN BAG1 TIUB KOMPOSIT HEKSAGON Oleh
MUNIR FARAJ M. ALKABIR Mac 2004 Pengerusi: Profesor Madya Abdel Magid Salem Hamouda, Ph.D. Fakulti
: Kejuruteraan
Satu eksperimen dan analisis unsur terhingga telah dijalankan bagi mengkaji kesan dimensi t iub k omposit h eksagon k e a tas r agam kegagalan d an k eupayaan p enyerapan tenaga. Sepanjang kajian ini, tiub heksagon dengan nisbah bidang yang berbeza bagi panjang lawan ketebalan (Llt) berubah
daripada 30 kepada 100 dan sudut-sudut
heksagon yang berbeza berubah daripada 35" kepada 60" pada tokokan 5" telah dikaji di bawah keadaan beban paksian.
Kesemua t iub h eksagon yang d iuji t elah d ibikin d aripada j alinan b iasa fabriklepoksi. Kesan geometri heksagon ke atas keupayaan
membawa beban dan keupayaan
penyerapan tenaga telah dipersembahkan. Satu model unsur terhingga bagi meramal keupayaan membawa beban, jejaring ubah bentuk dan kontor-kontor tegasan pada tahap pra-hancur bagi tiub heksagon di bawah keadaan beban paksian telah dibangunkan.
Keputusan-keputusan eksperimen menunjukkan bahawa geometri heksagon (panjang lawan pengecilan sisi) menambah keupayan membawa beban sebanyak 32.0, 13.8, 2.1
dan 18.7 bagi sudut sisi heksagon 35', 45", 50' dan 55". Keupayaan membawa beban telah dikurangkan sebanyak 49.6 dan 29.6 bagi sudut-sudut sisi heksagon 400 dan 600. Penyerapan tenaga juga bertambah sebanyak 1.4 dan 1.5 bagi sudut-sudut sisi heksagon 35' dan 60' dan penyerapan tenaga telah dikurangkan sebanyak 48.6, 11.6,20.0 dan 46.7 bagi s udut s isi h eksagon 4 0 O, 4 5 ', 5 0 'd an 5 5 '. P eramalan-peramalan model unsur terhingga telah dikorelasi dengan keputusan-keputusan eksperimen. Variasi antara eksperimen dan unsur terhingga ialah dalam julat 5.9 ke 9.8. Kesan goemetri bagi jalinan biasa fabriklepoksi (sistem rantai cincin dalam
bentuk heksagon) ke atas
kelakuan penghancuran, keupayaan menyerap tenaga, beban-beban kegagalan hancur dan ragam-ragam kegagalan telah juga dikaji.
Ragam-ragam kegagalan telah diperiksa menggunakan beberapa
gambarfoto yang
diambil semasa tahap-tahap penghancuran bagi setiap eksperimen. Ragam-ragam kegagalan yang utama yang berlaku semasa eksperimen adalah lengkokan setempat, ragam kegagalan bencana dan ragam kegagalan matriks.
ACKNOWLEDGEMENTS
In the name of Allah, Most Gracious, Most Merciful
First, by the grace of Allah (sbt), the controller of the whole universe, who has provided me with good health to finish this work in time. Secondly, I would like to express my sincere gratitude to the Chairman of the Supervisory Committee Assoc. Prof. Dr. AbdelMagid Salem Hamouda for his continuous help, support and encouragement throughout this work.
I would like to express my appreciation to Dr. Elsadig Mahdi for his suggestions and
constructive criticisms given at different stages of this study.
I also wish to thank Assoc. Prof. Ir. Dr. Mohd Sapuan Salit for his necessary help, guidance and valuable suggestions.
I also wish to express my thanks to my friends in Faculty of engineering for their cooperation. Special thanks goes to Mr. Manshwi Kames Alkhey for his help.
I a m grateful to my country Libya for having offered me a scholarship to pursue the
graduate study at university Putra Malaysia. Special thanks go to all the lovely members of my family and relatives with out whose encouragement and overwhelming support to complete this study.
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1 certify that an Examination Committee met on 5h March 2004 to conduct the final examination of Munir Faraj M. Alkabir on his Master of Science thesis entitled "Crushing Behavior of Hexagonal Composite Tubes" in accordance with Universiti Pertanian Malaysia (Higher Degree) Act 1980 and Universiti Pertanian Malaysia (Higher Degree) Regulations 1981. The Committee recommends that the candidate be awarded the relevant degree. Members of the Examination Committee are as follows:
Shamsuddin Sulaiman, Ph.D. Associate Professor Faculty of Engineering Universiti Putra Malaysia (Chairman) P.R. Arora, Ph.D. Associate Professor Faculty of Engineering Universiti Putra Malaysia (Member) Yousf A. Khalid, Ph.D. Associate Professor Faculty of Engineering Universiti Putra Malaysia (Member) Ahmad Kamal Ariffin, Ph.D. Associate Professor Department of Mechanical Engineering Faculty of Engineering Universiti Kebangsaan Malaysia (Independent Examiner)
ProfessorIDeputy Dean School of Graduate Studies Universiti Putra Malaysia Date: ...
Vlll
1 7 JUN 2004
This thesis submitted to the Senate of Universiti Putra Malaysia and has been accepted as fulfillment of the partial requirements for the degree of Master of Science. The members of the Supervisory Committee are as follows:
Abdelmagid Salem Hamouda, Ph.D. Associate Professor Faculty of Engineering Universiti Putra Malaysia (Chairman) Elsadig Mahdi Ahmed, Ph.D. Faculty of Engineering Universiti Putra Malaysia (Member)
Ir. Mohd Sapuan Salit,P.h.D. Associate Professor. Faculty of Engineering Universiti Putra Malaysia (Member)
AINI IDERIS, Ph.D. Professor1Dean School of Graduate Studies Universiti Putra Malaysia Date:
- 4 AUG 20M
DECLARATION
I hereby declare that the thesis is based on my original work except for quotations and citations, which have been duly acknowledged. I also declare that it has not been previously or concurrently submitted for any other degree at UPM or other institutions
Munir Faraj M. ~ l k b i y Date:
- 2 JUL
2004
,
TABLE OF CONTENTS
Page DEDICATION ABSTRACT ABSTRAK ACKNOWLEDGEMENTS APPROVAL DECLARATION LIST OF TABLES LIST OF FIGURES LIST OF NOMENCLATURE CHAPTER INTRODUCTION 1.1 General Introduction 1.2 Research Objectives 1.3 Significance of the Study 1.4 Thesis Layout LITERATURE REVIEW 2.1 Introduction 2.2 Composite Materials 2.2.1 Fibers 2.2.2 Glass Fibers 2.2.3 Matrices 2.3 Fabrication Methods of Composite Shells 2.3.1 Hand lay-up 2.3.2 Filament Winding 2.4 Energy Absorption Capability in Composite Material 2.4.1 Various Variables that Influence the Energy absorption Characteristics of Composite Material 2.5 Crushing Modes and Mechanisms 2.5.1 Catastrophic Failure Modes 2.5.2 Progressive Failure Modes 2.6 Failure Mechanisms 2.7 Crashworthiness Parameters in Composite Materials 2.7.1 Initial peak Load 2.7.2 Mean-Crushing Load 2.7.3 Crush Force Efficiency 2.7.4 Stroke Efficiency
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2.8
2.7.5 Initial Failure Indictor 2.7.6 Specific Energy Absorption Conclusion
METHODOLOGY 3.1 Experimental work 3.1 Geometry 3.2 Materials 3.3 Fabrication Process 3.4 Loading Condition 3.5 Test Procedure 3.6 Finite Element Simulation EXPERIMENTAL RESULTS 4.1 Introduction 4.2 Hexagonal Tube under Quasi-static Axial Crushing Load 4.2.1 Hexagonal Tube With Aspect Ratio (L/t=30) and different Angles (H.30.AP) Hexagonal Tube With Aspect Ratio (L/t=50) and different Angles (H.50.Ap) 4.2.3 Hexagonal Tube With Aspect Ratio (L/t=70) and different Angles (H.70.AP) 4.2.4 Hexagonal Tube With Aspect Ratio (L/t=100) and different Angles (H. 100.AP) Ring Chain System of Hexagonal Shape With Various Angles 4.3.1 Load-Displacement Relation 4.3.2 Specific Energy Absorption Capability-Displacement Relation 4.3.3 Crushing History and Failure Modes 4.3.4 Summary 4.2.2
4.3
FINITE ELEMENT RESULTS 5.1 Finite Element Method 5.2 Composite Hexagonal Tubes Modeling 5.3 Boundary Condition and Material Properties 5.4 Finite Element Result and Comparison with Experimental results CONCLUSIONS AND SUGGESTION FOR FUTURE WORK REFERENCES BIODATA OF THE AUTHOR
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LIST OF TABLES Table
Page
Specific energies of thermoplastic composite tubes with different fibers Mechanical properties of different resin Description of the fabric plain weave Hexagonal tubes Description of the ring chain system of hexagonal shape Type of composite material and matrix Crashworthiness parameters for Hexagonal composite tube with aspect ratio (L/t=30) and various angles Crashworthiness parameters for Hexagonal composite tube with aspect ratio (L/t=50) and various angles Crashworthiness parameters for Hexagonal composite tube with aspect ratio (L/t=70) and various angles Crashworthiness parameters for Hexagonal composite tube with aspect ratio (L/t=100) and various angles Crashworthiness parameters for Ring chain system of hexagonal Composite shape with various angles Typical engineering properties of materials used in this study Prediction of initial crush failure load (Pi)
...
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LIST OF FIGURES Figure
Page Variation of specific energy of carbon fiber1PEEK tubes with fiber Orientation (8) Load-Stroke curve: crush speed Schematic diagram of a composite tube specimen with one end Chamfer trigger Composite tubes crushed progressively a) fragmentation b) Splaymg modes Crushing characteristics of brittle fracturing crushing mode Local buckling crushing mode Micro-level failure mechanisms Schematic diagram of a typical force displacement curve Typical load-displacement curve for a progressively crushed Composite tube Flow chart describes the methodology used in this study Chart describes the experimental work (a) Cross sectional area (b) ring chain system of hexagonal shapes Schematic diagram for fabric plain weave fabrication process Schematic representation of the loading Conditions Flow chart describes the finite element work Load- displacement curves for hexagonal composite tube with aspect Ratio (Wt = 30) and various angles (35", 40°, 45", 50°, 55" and 60") Relations between hexagonal angles and average load Specific energy -displacement curve for hexagonal composite tubes with aspect ratio L/t=30 and different angles Typical load-displacement and crushing history for (H.30.35") Typical load-displacement and crushing history for (H.30.40°) Typical load-displacement and crushing history for (H.30.45") Typical load-displacement and crushing history for (H.30.50°) Typical load-displacement and crushing history for (H.3O.55")
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Typical load-displacement and crushing history for (H.30.6Oo) Load- displacement curves for hexagonal composite tube with aspect ratio (LIt = 50) and various angles (35", 40°, 45", 50°, 55" and 60") Relations between hexagonal angles and average load Specific energy -displacement curve for hexagonal composite tubes with aspect ratio L/t=50 and different angles. Typical load-displacement and crushing history for (H.50.35") Typical load-displacement and crushing history for (H.50.40°) Typical load-displacement and crushing history for (H.50.45") Typical load-displacement and crushing history for (H.50.50°) Typical load-displacement and crushing history for (H.50.55") Typical load-displacement and crushing history for (H.50.60°) Load- displacement curves for hexagonal composite tube with aspect ratio (Llt = 70) and various angles (35", 40°, 45", 50°, 55" and 60") Relations between hexagonal angles and average load Specific energy -displacement curve for hexagonal composite tubes with aspect ratio L/t=70 and different angles Typical load-displacement and crushing history for (H.70. 35") Typical load-displacement and crushing history for (H.70.40") Typical load-displacement and crushing history for (H.70. 45") Typical load-displacement and crushing history for (H.70. 50") Typical load-displacement and crushing history for (H.70. 55") Typical load-displacement and crushing history for (H.70. 60") Load- displacement curves for hexagonal composite tube with aspect ratio L/t= 100 and various angles (35", 40°, 45", 50°, 55" and60°) Relations between hexagonal angles and average load (kN) Specific energy absorption capability -displacement curves for Hexagonal composite tubes with aspect ratio (Llt=100) and different angles Typical load-displacement and crushing history for (H. 100. 35") Typical load-displacement and crushing history for (H. 100. 40") Typical load-displacement and crushing history for (H. 100. 45")
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Typical load-displacement and crushing history for (H. 100. 50")
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Typical load-displacement and crushing history for (H.100. 55")
4.36
Typical load-displacement and crushing history for (H. 100. 60") Load- displacement curves for ring chain system of hexagonal shape with P=(35", 40", 45", 50°, 55" and 60") Average Load- displacement curves for ring chain system of hexagonal P=(35", 40°, 45", 50°, 55" and 60") Specific energy absorption capability - displacement curves for ring chain system of hexagonal shape with (P=35", 40°, 45", 50°, 55" and 60") Load-deformation curve of ring chain system of hexagonal composite shape with P=3 5" Load-deformation curve of ring chain system of hexagonal composite shape with P=40° Load-deformation curve of ring chain system of hexagonal composite shape with P=45" Load-deformation curve of ring chain system of hexagonal composite shape with P=50° Load-deformation curve of ring chain system of hexagonal composite Shape with P=55" Load-deformation curve of ring chain system of hexagonal composite Shape with P=60" Flow chart describes the Eigenvalue analysis using LUSAS finite element program Typical mesh for axially loaded of composite hexagonal Tube Experimental and finite element deformed mesh together with stress contours for axially loaded composite tube with aspect ratio (L/t=30 and P=55") Experimental and finite element deformed mesh together with stress contours for axially loaded composite tube with aspect ratio (L/t=50 and P=45")
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108
Experimental and finite element deformed mesh together with stress contours for axially loaded composite tube with aspect ratio (L/t=70and P=45") Experimental and finite element deformed mesh together with stress contours for axially loaded composite tube with aspect ratio (L/t=l OOand P=50°)
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LIST OF NOMENCLATURE Cross sectional are of hexagonal tube Dimension of hexagonal tube Crush force efficiency Specific energy absorption Initial failure indicator Aspect ration of hexagonal tube Weight of the specimens
sE
Stroke efficiency
I3
Hexagonal angle
(H. A Llt. A p) hexagonal tube with different aspect ratio (Llt) different angles varying
PC,
Critical crushing load
Pi
Initial crushing load Mean - crushing load
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CHAPTER 1
INTRODUCTION 1.1. General Introduction
Materials have such an influence on our lives that the historical period of humankmd have been dominated, and named, after materials over the last thirty years, composite materials, plastics, and ceramics have been the dominant emerging materials. The volume and number of applications of composite material has grown steadily, penetrating and conquering new markets (relentlessly).
Composite materials are formed by a combination of two or more materials to achieve properties (physical, chemical, ect) that are superior to those of its constituent. The main components of composite material, or composites, are fiber and matrix. Fiber provides most of the stiffness and strength, and the matrix binds the fiber together thus providing load transfer between fiber and between the composite and the external loads and supports. The matrix is the principal phase in which other constituents (e.g., reinforcement, or fillers) are embedded or surrounding the reinforcement is material used to reinforce, strengthen or give dimensional stability.
The reasons for choosing composites in automotive applications include lower weight and greater durability (improved corrosion resistance, fatigue life, wear and impact resistance). Applications include drive shafts, fan blades, tires, brake shoes, clutch plates, gaskets, hoses, belts, and engine parts hybrid composite drive shaft for trucks manufactured by pultrusion where carbon and glass fiber composite are pultuded over aluminum cylinder to create a drive shaft that is significantly lighter and less expensive.
The use of advanced composites in structures such as bridges and buildings has lagged behind applications in other areas. One major reason for this is that weight is not an important consideration in static structures. However, as the benefits of reduced. An interesting example is the use of maintenance and erection costs combine with architectural enhancements are recognized, the application of composite in these structures will follow. Composites are also in use in lightweight overhead walkways, as well as lighting and communications poles [I].
Composite tube is common structural components that can be used for a wide variety of applications. Some of these applications include oil pipelines, trusses for space vehicles and chassis of automobiles. Composite materials offer the stiffness of conventional metal at a lower weight. With this viewpoint, the automotive industry is currently exploring to adapting more fiber reinforced polymer matrix composites into automobile bodies. The amount of energy that vehicle absorbs during a collision is a matter of concern to ensure safer and more reliable vehicles. If composite can be economically manufactured and be made to offer equivalent energy absorption under impact as metals
at a fraction of the weight, the savings to both automakers and consumers would be substantial.
Investigations of crushing energy absorption are important and are expected from the point of view of safety design of passenger vehicles. In order to reduce the damage to occupants in a collision, it necessary to understand the crushing behavior and to enhance the energy absorbing capability of tubular structures [2]. In passenger vehicles the ability to absorb impact energy and be survivable for the occupant is called the "crashworthiness" of the structure. This absorption of energy is through controlled failure mechanisms and modes that enable the maintenance of a gradual decay in the load profile [3].
Usually the experimental analysis is more common, but finite element also is getting a great attention for its quick results. The effect of the number of layers, type of the fiber, type of the matrix and fiber orientation angles were the common features which are usually evaluated for each structure by developing the load-displacement and energy absorption relation. Several researches were carried out on composite materials and structures to evaluate their properties, strength, and behavior structures including cylinders plats, and cones, which were tested experimentally and theoretically.
Throughout this investigation, the investigation of energy absorption capability in hexagonal composite tube is carried out experimentally and numerically under an axial
crashing load by using the finite element method. Also, the experimental validation has been done in the crushing behavior of composite hexagonally ring system under lateral cashing load. The effects of mandrel geometry on crashworthiness performance of fabric plain weave /epoxy hexagonal tubes and ring chain system and their effects on energy absorption capabilities have been observed.
1.2 Research Objectives
The main objectives of this work are:
To study the effects of geometry of hexagonal composite tube and ring chain systems with hexagonal shape on crushing behavior. To investigate the energy absorption capability of hexagonal composite tubes and ring chain system with hexagonal shape
1.3 Significance of the Study
Composite materials are rapidly becoming potential substitutes for metal due to their higher strength and stiffness-to-weight ratio, improved corrosion resistance, styling enhancement and the reeducation of fabrication maintenance costs. The efficient use of hexagonal composite tubes as energy absorber depends on the understanding of their crushing behavior.
The generated data from this study can be useful in design phase of energy absorber element made from composite material.
1.4 Thesis Layout
This thesis is divided into seven chapters. Following this introduction Chapter, chapter two presents a review of literature related to matrix and reinforcement, advantages and Classification of composite material. Crushing behavior and energy absorption characteristics of composite structures are also discussed. The methodology used in this study is explained in chapter three. Chapter four presents the experimental results. Finite element results are presented and discussed in chapter five. Finally in chapter six, conclusion from the work and the proposal for future studies are listed
CHAPTER 2
LITERATURE REVIEW
2.1 Introduction
In this chapter, literatures related to composite materials are reviewed. Attention is directed towards, fabrication methods, energy absorption capability in composite material, crushing modes and mechanisms and crashworthiness parameters in composite materials are discussed in details.
2.2 Composite Materials
The general definition of composite material is very closely related to the dictionary definition of the word composite, meaning made up of different parts or materials. Composite materials are constructed from two or more materials, commonly referred to as constituents, and have characteristics derived from the individual constituents. Depending on the manner in which the constituents are put together the resulting composite material may have the combined characteristics of the constituents, this according to Gurdal, and Hajela [4].
