Self-Healing Composites (eBook)

Shape Memory Polymer Based Structures

Guoqiang Li (Autor)

eBook Download: EPUB

2014
John Wiley & Sons (Verlag)
978-1-118-45245-5 (ISBN)

Infos

In this book, the self-healing of composite structures with shape memory polymer as either matrix or embedded suture is systematically discussed. Self-healing has been well known in biological systems for many years: a typical example is the self-healing of human skin. Whilst a minor wound can be self-closed by blood clotting, a deep and wide cut needs external help by suturing. Inspired by this observation, this book proposes a two-step close-then-heal (CTH) scheme for healing wide-opened cracks in composite structures–by constrained shape recovery first, followed by molecular healing. It is demonstrated that the CTH scheme can heal wide-opened structural cracks repeatedly, efficiently, timely, and molecularly. It is believed that self-healing represents the next-generation technology and will become an engineering reality in the near future.  

The book consists of both fundamental background and practical skills for implementing the CTH scheme, with additional focus on understanding strain memory versus stress memory and healing efficiency evaluation under various fracture modes. Potential applications to civil engineering structures, including sealant for bridge decks and concrete pavements, and rutting resistant asphalt pavements, are also explored.  This book will help readers to understand this emerging field, and to establish a framework for new innovation in this direction.

Key features:

• explores potential applications of shape memory polymers in civil engineering structures, which is believed to be unique within the literature
• balanced testing and mathematical modeling, useful for both academic researchers and practitioners
• the self-healing scheme is based on physical change of polymers and is written in an easy to understand style for engineering professionals without a strong background in chemistry

Autor

Guoqiang Li is the author of Self-Healing Composites: Shape Memory Polymer Based Structures, published by Wiley.

Inhalt

Preface xiii

1 Introduction 1

1.1 Thermosetting Polymers 1

1.2 Thermosetting Polymer Composites in Structure Applications 3

1.3 Damage in Fiber Reinforced Thermosetting Polymer Composite Structures 3

1.4 Repair of Damage in Thermosetting Polymer Composite Structures 11

1.5 Classification of Self-Healing Schemes 13

1.6 Organization of This Book 14

References 15

2 Self-Healing in Biological Systems 21

2.1 Self-Healing in Plants 21

2.2 Seal-Healing in Animals 21

2.3 Self-Healing in Human Beings 26

2.4 Summary Remarks 29

2.5 Implications from Nature 30

References 30

3 Thermoset Shape Memory Polymer and Its Syntactic Foam 35

3.1 Characterization of Thermosetting SMP and SMP Based Syntactic Foam 38

3.2 Programming of Thermosetting SMPs 48

3.3 Thermomechanical Behavior of Thermosetting SMP and SMP Based Syntactic Foam Programmed Using the Classical Method 54

3.4 Thermomechanical Behavior of Thermosetting SMP and SMP Based Syntactic Foam Programmed by Cold Compression 77

3.5 Behavior of Thermoset Shape Memory Polymer Based Syntactic Foam Trained by Hybrid Two-Stage Programming 86

3.6 Functional Durability of SMP Based Syntactic Foam 102

References 105

4 Constitutive Modeling of Amorphous Thermosetting Shape Memory Polymer and Shape Memory Polymer Based Syntactic Foam 109

4.1 Some Fundamental Relations in the Kinematics of Continuum Mechanics 111

4.2 Stress Definition in Solid Mechanics 119

4.3 Multiplicative Decomposition of Deformation Gradient 121

4.4 Constitutive Modeling of Cold-Compression Programmed Thermosetting SMP 123

4.5 Thermoviscoplastic Modeling of Cold-Compression Programmed Thermosetting Shape Memory Polymer Syntactic Foam 139

References 150

5 Shape Memory Polyurethane Fiber 155

5.1 Strengthening of SMPFs Through Strain Hardening by Cold-Drawing Programming 155

5.2 Characterization of Thermoplastic SMPFs 169

5.3 Constitutive Modeling of Semicrystalline SMPFs 179

5.4 Stress Memory versus Strain Memory 200

References 208

6 Self-Healing with Shape Memory Polymer as Matrix 213

6.1 SMP Matrix Based Biomimetic Self-Healing Scheme 219

6.2 Self-Healing of a Sandwich Structure with PSMP Based Syntactic Foam core 245

6.3 Grid Stiffened PSMP Based Syntactic Foam Cored Sandwich for Mitigating and Healing Impact Damage 260

6.4 Three-Dimensional Woven Fabric Reinforced PSMP Based Syntactic Foam Panel for Impact Tolerance and Damage Healing 270

References 281

7 Self-Healing with Embedded Shape Memory Polymer Fibers 287

7.1 Bio-inspired Self-Healing Scheme Based on SMP Fibers 287

7.2 SMP Fiber versus SMA (Shape Memory Alloy) Fiber 289

7.3 Healing of Thermosetting Polymer by Embedded Unidirectional (1-D) Shape Memory Polyurethane Fiber (SMPF) 293

7.4 Healing of Thermosetting Polymer by Embedded 2-D Shape Memory Polyurethane Fiber (SMPF) 307

7.5 Healing of Thermosetting Polymer by Embedded 3-D Shape Memory Polyurethane Fiber (SMPF) 314

References 325

8 Modeling of Healing Process and Evaluation of Healing Efficiency 329

8.1 Modeling of Healing Process 330

8.2 Evaluation of Healing Efficiency 334

8.1 Modeling of Healing Process 330

8.2 Evaluation of Healing Efficiency 334

References 351

9 Summary and Future Perspective of Biomimetic Self-Healing Composites 355

9.1 Summary of SMP Based Biomimetic Self-Healing 355

9.2 Future Perspective of SMP Based Self-Healing Composites 356

References 364

Index 367

Textauszug

Preface

The history of human beings and advancement of civilization are generally categorized by the ability to produce and manipulate materials to meet the needs of the society, such as the Stone Age, Bronze Age, Iron Age, and Silicon Age. It is reasonable to ask what will be next. For many practical engineering applications, materials need to be lighter, stronger, tougher, smarter, and cost-effective. While lighter, stronger, and tougher materials have been a major theme in modern structure design for many years, smarter materials and structures are a comparatively new paradigm. Although it is difficult to define the exact meaning of smarter, because it evolves with time, the big picture is clear. We desire the synthetic materials and engineering structures to possess intelligence that is commensurate with or better than their biological counterparts. We are optimistic that synthetic materials can be better than biological counterparts because we have more types of elements to use while biomaterials build on a few types of atoms. Also, we have more knowledge of various biological systems and we have the ability to analyze, compare, combine, create, design, optimize, and manufacture materials and structures. With the advancement in the understanding of micro, nano, and molecular structures, as well as high fidelity computation technology, the concept of materials by design seems to be opening up endless opportunities for discovering and synthesizing new materials. However, no matter how powerful is the computation technology, scientists and engineers must have targets or pictures in mind, that is, visualizing and imagining what they want before they can start designing the materials by computation. We believe that the motivation should come from observation of nature.

Historically, bio-inspiration has been a driving force for the advancement of science and technology. The reason is simple. Mother nature has evolved millions and millions years and developed sophisticated natural materials or assemblies with multifunctions and properties. In today's technological understanding, most of the natural materials are smart. They sense, adapt, and react to external stimuli and, of course, self-heal internal damage. There are three levels of learning from nature, namely, bioinspiration, biomimicry, and bioreplication, with increasing complexity.

The purpose of bioinspiration is to recreate biological functions but not necessarily biological structures. An aircraft is an excellent example of bioinspiration of birds. The purpose of biomimicry is to recreate the biological functions by approximately replicating the biological structures. Dry adhesive by mimicking a gecko foot may be an example of biomimicry. The purpose of bioreplication is the direct reproduction of biological functions by replicating the biological structures. Because most biological structures are hierarchical and very complex, bioreplication is in its infancy. Based on current science and technology, we believe that the next generation of synthetic materials should be biomimetic smart materials by learning from mother nature, if not bioreplication. We must admit that, as compared to natural materials, the smart synthetic materials available are still in their infancy. We still have a long way to go and many challenges to overcome before we can mimic the simplest natural materials.

In the past several decades, the desire for lighter, tougher, and stronger materials in vehicles (car, aircraft, ship, bike, etc.), energy production, storage, and transport (windmill blade, piping, offshore oil platform, pressure vessel, on-board and off-board energy storage tank, etc.), and infrastructure (bridge, harbor, building, etc.) has driven the development of fiber reinforced polymer composite materials. Fiber reinforced polymer composite materials, while having high specific strength, stiffness, and corrosion resistance, are vulnerable to foreign object impact, due to stress concentration at various interfaces and brittleness of thermosetting polymer matrix, such as epoxy and synthetic fibers like glass fiber. In addition to the well-known ballistic impact, which can be visually detected by operators, low velocity impact is more dangerous in the sense that it usually avoids visual inspection. For example, a low velocity impact on a laminated composite may leave a barely visible indentation at the point of impact, but macroscopic cracks are likely to have been created at the back surface or inside the laminate. Low velocity impact is not uncommon. For instance, for aircraft, hail, bird strike during taking off or landing, debris strike in the runway, or even dropping a tool during routine inspection represent typical low velocity impact events. Therefore, for fiber reinforced polymer composite structures, while damage healing at the microscopic level such as healing a fatigue crack (micrometer or submicrometer scale) is essential, it is important that the composite has the ability to heal wide-opened macroscopic cracks such as delamination in the millimeter scale. There is no doubt that in fiber reinforced polymer composite materials, fibers are the primary load bearing component. Therefore, it is natural to think that we need to heal synthetic fibers such as carbon fibers and glass fibers, similar to healing the bone in a human body. While this is a legitimate attempt, it is extremely difficult based on current knowledge and technology. Of course, it is an interesting topic for materials scientists to pursue.

Actually, in fiber reinforced polymer composites, matrix dominated damage represents the major damage mode up to a certain loading level. Therefore, healing damage in the polymer matrix is not trivial. Because of the role played by the matrix in composites, healing matrix damage serves to recover the load carrying capacity, protect the fiber from damage, and extend the service life of the composite. Therefore, similar to studies by others, this book will focus on healing macroscopic damage in the polymer matrix. Another argument may be that, if the crack is wide-opened, it is visible with the naked eye, and thus directly injecting adhesive into the crack would heal the composite. This seems a legitimate argument and may be the case for some structures. However, it is not the case for many others, such as delamination and matrix cracking in a laminated composite and cracking in the foam core and debonding at the core/face sheet interface in a sandwich composite, which are inside the structures and inaccessible. Therefore, self-healing of a macroscopic crack in a polymer matrix is a genuine problem that deserves investigation. Unfortunately, healing structural-length scale damage represents a grand challenge for both intrinsic and extrinsic self-healing schemes. The reason is that almost all of them need external help to bring the fractured surfaces in proximity before the self-healing mechanisms can take effect.

Since 2006, our group has focused on healing of structure-length scale crack in shape memory polymer (SMP) based composite. Our first paper was published in 2008 in Composites Science and Technology. In 2010, we reported the bio-inspired two-step self-healing scheme, that is, close-then-heal (CTH), in several publications and with more and more details and depth. In CTH, we realized that for a wide-opened crack, we need to close/narrow the crack before we heal it molecularly, similar to self-healing of human skin. We demonstrated that CTH can heal low velocity impact induced damage in various types of composite structures, repeatedly, efficiently, molecularly, and timely. Most recently we have extended this concept to healing conventional thermosetting polymer composite by embedding SMP fibers. We have also conducted modeling work to understand the constitutive behavior of SMPs and SMP based composite better, as well as damage–healing mechanisms.

This book grew out of the work done in our group in the past several years. It is by no means a comprehensive representation of the entire self-healing picture. As self-healing has become a popular topic in both academia and industry, we hope this book will provide some background information for readers who are interested in using SMPs for self-healing. We are optimistic that self-healing materials and structures will become an engineering reality in the coming years rather than scientific fiction.

This book is arranged as follows. Chapter 1 will introduce some basics on damage in various composite structures and classification of self-healing schemes. Chapter 2 will focus on the introduction of self-healing in biological systems, which inspired the self-healing scheme in this book. Chapter 3 will focus on the thermomechanical behavior of thermosetting SMPs and SMP based syntactic foam. The effect of programming temperature (hot programming and cold programming) as well as programming stress condition (1-D, 2-D, and 3-D stress conditions) on the shape memory effect will be presented. Functional stability under environmental attacks will also be briefly discussed. Chapter 4 will provide some basics on solid mechanics modeling and discuss the two popular strategies to model SMPs – thermodynamic based and stress/structural relaxation based approaches. Modeling on both thermosetting SMP and SMP based syntactic foam will be reported. Chapter 5 will focus on testing and modeling of polyurethane SMP fibers, including physical, mechanical, thermomechanical, damping, and microstructure characterization. Viscoplasticity theory will be presented to model the effect of strain hardening by cold-drawing programming on stress recovery. The underlying mechanisms controlling the difference in strain memory and stress memory will be discussed....

Produkt-Details

• Erscheint lt. Verlag: 23.9.2014
• Sprache: englisch
• Themenwelt: Technik ► Maschinenbau
• Schlagworte: biological • Blood • Book • Bruchmechanik • composite • Deep • Discussed • either • Example • External • Failure Fracture • Human • known • many • Maschinenbau • Materials Science • Materialwissenschaften • Matrix • mechanical engineering • Memory • Metalle u. Legierungen • Metals & Alloys • minor wound • Observation • Physics • Physik • Polymer • Polymer Physics • Polymerphysik • SelfHealing • Shape • Skin • Structures • Suture • systematically • Systems • typical • years
• ISBN-10: 1-118-45245-3 / 1118452453
• ISBN-13: 978-1-118-45245-5 / 9781118452455