Structural Composite Materials

This book deals with all aspects of advanced composite materials; what they are, where they are used, how they are made, their properties, how they are designed and analyzed, and how they perform in-service. It covers both continuous and discontinuous fiber composites fabricated from polymer, metal, and ceramic matrices, with an emphasis on continuous fiber polymer matrix composites.

The book starts with an overview of composite materials and how highly anistropic composites differ from isotropic materials, such as metals. Some of the important advantages and disadvantages of composites are then discussed. The first chapter wraps up with some of the applications for advanced composites. Next, the reinforcements and their product forms are covered with an emphasis on glass, aramid, and carbon fibers. This is followed by a chapter on polymer matrix resin systems, covering the main thermosetting and thermoplastic resin systems, including polyesters, vinyl esters, epoxies, bismaleimides, cynate esters, polyimides, and phenolics. The principles of resin toughening are also presented, along with an introduction to the physiochemical tests that are used to characterize resin and cured laminates.

The next part of the book covers polymer composite fabrication processes, with chapters on cure tooling, thermoset composite fabrication processes, and thermoplastic composites fabrication processes. Important thermoset lay-up methods include wet lay-up, prepreg lay-up, automated tape laying, fiber placement, filament winding, and pultrusion. Vacuum bagging in preparation for cure is also discussed along with the cure processes for both addition and condensation curing thermosets. Thermoset liquid molding covers preforming technology (weaving, knitting, stitching, and braiding) followed by the major liquid molding processes, namely resin transfer molding (RTM), resin film infusion (RFI), and vacuum assisted resin transfer molding (VARTM).

In a chapter on thermoplastic composite fabrication processes, thermoplastic composite consolidation is covered along with the different methods of thermoforming thermoplastics. Finally, the joining processes that are unique to thermoplastic composites are discussed. After these processing fundamentals are set, there is a chapter that deals with some of the detailed processing issues unique to thermoset and thermoplastic composites. The concept of cure modeling is introduced along with the importance of both lay-up and cure variables, hydrostatic resin pressure, chemical composition, resin and prepreg, debulking, and caul plates. Residual cure stresses and exothermic reactions are also covered followed by methods for in-process cure monitoring.

Adhesive bonding, sandwich, and integrally cocured structures are introduced in two chapters. The basics of adhesive bonding are covered along with its advantages and disadvantages. The importance of joint design, surface preparation, and bonding procedures are discussed along with honeycomb bonded assemblies, foam bonded assemblies, and integrally cocured assemblies.

There is a chapter on the types, properties, and fabrication technology for discontinuous fiber polymer matrix composites, with an emphasis on spray-up, compression molding, structural reaction injection molding, and injection molding.

In a chapter on assembly, the emphasis is on mechanical joining including the hole preparation procedures and fasteners used for structural assembly. Sealing and painting are also briefly discussed.

The next four chapters cover the test methods and properties for composite materials. Nondestructive test methods include visual, ultrasonics, radiographic, and thermographic inspection methods. Mechanical property test methods include tests for both composite materials and adhesive systems. In the next chapter, the strength and stiffness for both discontinuous and continuous reinforced composites are compared. There is also a chapter that covers the types of environmental degradation, including moisture absorption, fluids exposure, ultraviolet radiation and erosion, lightning strikes, thermo-oxidative behavior, heat damage, and flammability.

The next three chapters cover the analysis, design, and repair of composites. Structural analysis starts with analysis at the lamina, or ply, level and then uses classical lamination theory to illustrate the analysis methods for more complex laminates. The concept of interlaminar free edge stresses is introduced. Four failure theories are discussed: the maximum stress criterion, the maximum strain criterion, the Azzi-Tsai-Hill maximum work theory, and the Tsai-Wu failure criterion. The analysis of composite joints, both bolted and bonded, is covered in a separate chapter. There is also a chapter that deals with composite design and certification considerations, including materials and process selection, design trade studies, the building block approach to certification, design allowables, and design guidelines. Considerations for handling damage tolerance and environmental issues are also discussed. The chapter on repair of composites includes fill repairs, injection repairs, bolted repairs, and bonded repairs.

The last two chapters cover metal and ceramic matrix composites. The reinforcements, matrix systems, and fabrication technology for both materials are discussed.

It is anticipated that this book could be read and understood by anyone with a technical background. A first course in materials science would be helpful but not absolutely essential. It does assume a basic knowledge of mathematics, chemistry, and physics. The intended audience would primarily be technical people working in industry. It would be useful to almost anyone who deals with composites, including designers, structural engineers, material and process engineers, manufacturing engineers, and production supervisors.

The unique feature of this book is that it provides a comprehensive overview of composite materials at the introductory to intermediate level from an industrial perspective. Other books on composite materials stress theory more than practical applications. Throughout this book, practical aspects are emphasized more than theory. Since the author spent 38 years in industry, the information covers the current state of the art in composite materials.

Preface
About the Author

Chapter 1 : Introduction to Computer Materials
Chapter 2 : Fibers and Reinforcements
Chapter 3 : Matrix Resin Systems
Chapter 4 : Fabrication Tooling
Chapter 5 : Thermoset Composites Fabrication Process
Chapter 6 : Thermoplastics Composite Fabrication Processes
Chapter 7 : Processing Science of Polymer Matrix Composites
Chapter 8 : Adhesive Bonding
Chapter 9 : Sandwich and Integral Cocured Structure
Chapter 10 : Discontinuous-Fiber Composites
Chapter 11 : Machining and Assembly
Chapter 12 : Nondestructive Inspection
Chapter 13 : Mechanical Property Test Methods
Chapter 14 : Composites Mechanical Properties
Chapter 15 : Environment Degradation
Chapter 16 : Structural Analysis
Chapter 17 : Structural Joints-Bolted and Bonded
Chapter 18 : Design and Certification Considerations
Chapter 19 : Repair
Chapter 20 : Metal Matrix Composites
Chapter 21 : Ceramic Matrix Composites

Appendix A Metric Conversion Factors
Index