Structural Adhesive Joints Design, Analysis, and Testing

This timely book on structural adhesives joints showcases all the pertinent topics and will be of immense value to scientists and engineers in many industries.

Most structures are comprised of a number of individual parts or components which have to be connected to form a system with integral load transmission path. The structural adhesive bonding represents one of the most enabling technologies to fabricate most complex structural configurations involving advanced materials (e.g. composites) for load-bearing applications. Quite recently there has been a lot of activity in harnessing nanotechnology (use of nanomaterials) in ameliorating the existing or devising better performing structural adhesives.

The 10 chapters by subject matter experts look at the following issues:

• Surface preparation for structural adhesive joints (SAJ)
• Use of nanoparticles in enhancing performance of SAJ
• Optimization of SAJ
• Durability aspects of SAJ
• Debonding of SAJ
• Fracture mechanics of SAJ
• Failure analysis of SAJ
• Damage behavior in functionally graded SAJ
• Impact, shock and vibration characteristics of composites for SAJ
• Delamination arrest methods in SAJ

Kashmiri Lal Mittal was employed by the IBM Corporation from 1972 through 1993. Currently, he is teaching and consulting worldwide in the broad areas of adhesion as well as surface cleaning. He has received numerous awards and honors including the title of doctor honoris causa from Maria Curie-Sk??odowska University, Lublin, Poland. He is the editor of more than 130 books dealing with adhesion measurement, adhesion of polymeric coatings, polymer surfaces, adhesive joints, adhesion promoters, thin films, polyimides, surface modification surface cleaning, and surfactants. Dr. Mittal is also the Founding Editor of the journal Reviews of Adhesion and Adhesives.

S. K. Panigrahi (PhD, IIT Kharagpur) is a Professor in the Department of Mechanical Engineering of Defence Institute of Advanced Technology (DIAT), Pune, India. He has worked as an International Visiting Academic with University of New South Wales at the Australian Defence Force Academy (UNSW@ADFA). He has more than 27 year of wide and intensive teaching, research, training and administrative experience. He has been working on the development of advanced finite element methods and nonlinear finite element analyses and modelling of engineering structures with functionally graded/monolithic adhesively bonded joints. He has published over 190 research articles in peer-reviewed scholarly research papers international journals/conferences including 4 books, a monograph and many conference proceedings including a series of lecture materials.

Preface xiii

Part 1: General Topics 1

1 Surface Preparation for Structural Adhesive Joints 3
Anushka Purabgola, Shivani Rastogi, Gaurav Sharma and Balasubramanian Kandasubramanian

1.1 Introduction 4

1.2 Theories of Adhesion 6

1.2.1 Mechanical Interlocking 6

1.2.2 Electrostatic (Electronic) Theory 7

1.2.3 Diffusion Theory 7

1.2.4 Wetting Theory 8

1.2.5 Chemical Bonding Theory 10

1.2.6 Weak Boundary Layer Theory 10

1.3 Surface Preparation Methods 11

1.3.1 Degreasing 12

1.3.1.1 Vapor Degreasing 12

1.3.1.2 Ultrasonic Vapor Degreasing 13

1.3.1.3 Other Degreasing Methods 14

1.3.2 Mechanical Abrasion 15

1.3.3 Chemical Treatment 17

1.3.3.1 Acid Etching 17

1.3.3.2 Anodization 17

1.3.4 Physical Methods 20

1.3.4.1 Corona Treatment 20

1.3.4.2 Flame Treatment 22

1.3.4.3 Plasma Treatment 22

1.4 Surface Preparation Evaluation Methods 23

1.4.1 Dyne Solutions 24

1.4.2 Water-Break Test 24

1.4.3 Contact Angle Test 24

1.5 Applications of Structural Adhesives 25

1.5.1 Adhesives for Aerospace 25

1.5.2 Adhesives for Marine Applications 26

1.5.3 Adhesives for Medical and Dental Applications 26

1.5.4 Adhesives for Construction 27

1.5.5 Adhesives for Automotive Industry 28

1.5.6 Adhesives for Electronics 28

1.6 Summary 29

Acknowledgment 29

References 30

2 Improvement of the Performance of Structural Adhesive Joints with Nanoparticles and Numerical Prediction of Their Response 35
Farid Taheri

2.1 Introduction 36

2.1.1 Historical Perspective 36

2.1.2 Incorporation of Fillers in Adhesives 38

2.2 Use of Nanocarbon Nanoparticles for Improving the Response of Resins and Adhesives 41

2.3 Assessment of Performance of Adhesively Bonded Joints (ABJs) 54

2.3.1 Brief Introduction to the Procedures Used for Assessing Stresses in ABJs 54

2.3.2 Computational Approaches for Assessing Response of ABJs 56

2.4 Application of CZM for Simulating Crack Propagation in Adhesively Bonded Joints 60

2.4.1 Basis of the CZM 60

2.4.2 Applications of CZM to Bonded Joints 62

2.5 Application of xFEM for Simulating Crack Propagation in Adhesively Bonded Joints 66

2.6 Summary 69

Acknowledgement 70

References 70

3 Optimization of Structural Adhesive Joints 79
P. K. Mallick

3.1 Introduction 79

3.2 Joint Configurations 80

3.3 Joint Design Parameters 83

3.4 Substrate Stiffness and Strength 88

3.5 Adhesive Selection 89

3.6 Hybrid Joints 92

3.7 Summary 93

References 94

4 Durability Aspects of Structural Adhesive Joints 97
H. S. Panda, Rigved Samant, K. L. Mittal and S. K. Panigrahi

Abbreviations Used 98

4.1 Introduction 99

4.2 Factors Affecting Durability 100

4.2.1 Materials 101

4.2.1.1 Adhesives 101

4.2.1.2 Adherends 111

4.2.2 Environment 123

4.2.2.1 Moisture 123

4.2.2.2 Coefficient of Thermal Expansion (CTE) 124

4.2.3 Stress 125

4.3 Methods to Improve Durability 127

4.4 Summary 128

References 129

5 Debonding of Structural Adhesive Joints 135
Mariana D. Banea

5.1 Introduction 135

5.2 Design of Structures with Debondable Adhesives (Design for Disassembly) 138

5.3 Techniques for Debonding of Structural Adhesive Joints 140

5.3.1 Electrically Induced Debonding of Adhesive Joints 140

5.3.2 Debonding on Demand of Adhesively Bonded Joints Using Reactive Fillers 141

5.3.2.1 Nanoparticles 141

5.3.2.2 Microparticles 145

5.4 Prospects 151

5.5 Summary 152

Acknowledgements 152

References 152

Part 2: Analysis and Testing 159

6 Fracture Mechanics-Based Design and Analysis of Structural Adhesive Joints 161
Jinchen Ji and Quantian Luo

Abbreviations and Nomenclature 161

6.1 Introduction 163

6.1.1 Analysis Methods of Adhesive Joints 164

6.1.2 Design Philosophy of Adhesive Joints and Fracture Mechanics Based Design 166

6.2 Stress Analysis and Fracture Modelling of Structural Adhesive Joints 167

6.2.1 Stress Analysis and Static Strength of Structural Adhesive Joints 168

6.2.1.1 Shear-Lag Model and Shear Stress 168

6.2.1.2 Beam-Adhesive Model, Shear and Peel Stresses 171

6.2.1.3 Load Update of a Single Lap Joint in Tension 177

6.2.2 Analytical Approaches of Linear Elastic Fracture Mechanics 180

6.2.2.1 An Approach Based on Adhesive Stresses for the Joint Under General Loading 180

6.2.2.2 Methods Based on a Beam Theory and a Singular Field 184

6.2.3 Fracture Prediction Using Cohesive Zone Model 185

6.2.3.1 Cohesive Zone Model 186

6.2.3.2 Cohesive Traction Law 186

6.2.3.3 Design Criteria Based on Cohesive Zone Model 187

6.3 Finite Element Modelling and Simulation 187

6.3.1 Finite Element Modelling for Stress Analysis of Adhesive Joints 188

6.3.2 Virtual Crack Closure Technique 188

6.3.3 Cohesive Zone Modelling and Progressive Failure 189

6.4 Experimental Approach and Material Characterization 190

6.4.1 Specimen and Test Standard 191

6.4.2 Data Reduction and Fracture Toughness, Mixed Mode Fracture 192

6.4.3 Measurement of Fracture Parameters and Progressive Failure Using DIC 192

6.5 Prospects 193

6.5.1 Analytical Modelling and Formulation 193

6.5.2 Cohesive Zone Model and Progressive Fracture 193

6.5.3 Experimental Study on Fracture of Adhesive Joints 194

6.5.4 Optimal Design of Adhesive Joints and Use of Nanomaterials 194

6.6 Summary 195

References 195

7 Failure Analysis of Structural Adhesive Joints with Functionally Graded Tubular Adherends 205
Rashmi Ranjan Das

7.1 Introduction and Background Literature 206

7.2 Material Property Gradation in the Structural Adhesive Joint Region 210

7.3 Stress Analysis 212

7.4 Summary and Conclusions 216

References 217

8 Damage Behaviour in Functionally Graded Structural Adhesive Joints with Double Lap Joint Configuration 221
S. V. Nimje and S. K. Panigrahi

List of Symbols 222

8.1 Introduction 222

8.2 FE Analysis of Functionally Graded Double Lap Joint 227

8.2.1 Modelling of Double Lap Joint 227

8.2.2 Loading and Boundary Conditions 229

8.2.3 Modeling of Functionally Graded Adhesive Layer 229

8.2.4 Meshing Scheme of Double Lap Joint 231

8.2.5 Error and Convergence Study 231

8.3 Damage Onset in a Double Lap Joint 233

8.4 Adhesion/Interfacial Failure Propagation Analysis 234

8.4.1 Evaluation of SERR 235

8.5 Interfacial Damage Propagation Analysis 237

8.5.1 Onset of Adhesion/Interfacial Failure 237

8.5.2 Interfacial Failure Propagation in Double Lap Joint with Mono-Modulus Adhesive 238

8.5.3 Interfacial Damage Propagation in Functionally Graded Double Lap Joint 240

8.6 Conclusions 242

References 243

9 Impact, Shock and Vibration Characteristics of Epoxy-Based Composites for Structural Adhesive Joints 247
Bikash Chandra Chakraborty and Debdatta Ratna

Descriptions of Abbreviations 248

Symbols with Units 249

9.1 Introduction 250

9.2 Dynamic Viscoelasticity 252

9.2.1 Example 255

9.3 Toughened Epoxy Resins 257

9.3.1 Toughening Agents for Epoxy 258

9.4 Flexible Epoxy System 263

9.4.1 Vibration Response for Joined Beams 265

9.4.2 Experimental Evaluation 268

9.4.3 Flexible Epoxy-Clay Nanocomposite 270

9.5 Shock Response of Metallic Joints with Epoxy Adhesives 274

9.5.1 Shock Pulse: Fourier Transform 275

9.5.2 Shock Response 277

9.6 Summary 283

References 284

10 Delamination Arrest Methods in Structural Adhesive Joints Used in Automobiles 289
P. Ramesh Babu

10.1 Introduction 290

10.2 Delamination Growth Studies in Laminated FRP Composite Bonded Joints 290

10.2.1 Analysis of Embedded Delaminations 291

10.3 Laminated Curved Composite Skin-Stiffener Joint Geometry and Material Properties 292

10.3.1 Configurations of the Models with Pre-Embedded Delamination 293

10.3.2 Loads and Boundary Conditions of the Joint for the Delamination Analysis 295

10.4 Finite Element Modelling with Embedded Delamination 295

10.5 Numerical Method for the Delamination Analysis 296

10.6 Computations of SERRs for Hybrid Laminated Curved Composite Skin-Stiffener Joint 298

10.7 Studies of Crack Growth Arrest with Fasteners in Bonded Joints 304

10.7.1 Modelling and Analysis of Skin-Stiffener Joint with Fasteners at Embedded Delamination 304

10.8 Study of Crack Growth Arrest Mechanisms with Z-Fibre Pins in Composite Laminated Joints 307

10.9 Modelling and Analysis of Skin-Stiffener Joints with Z-Fiber Pins at Embedded Delamination 307

10.9.1 Estimation of Crack Growth Arrest (a) with Single Row of Z-Fiber Pins Reinforcement (b) with Multiple Rows of Z-Fiber Pins Reinforcement (c) Influence of Diameter and Space in between the Reinforced Pins on Fracture Toughness of the Composite Laminated Joint 308

10.10 Conclusions 312

10.11 Scope of Future Work 315

References 315

Index 319

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