A daring, original approach to understanding and predicting the mechanical behavior of materials

"Damage is an abstraction.... Strength is an observable, an independent variable that can be measured, with clear and familiar engineering definitions." (from the Preface to Damage Tolerance and Durability of Material Systems)

Long-term behavior is one of the most challenging and important aspects of material engineering. There is a great need for a useful conceptual or operational framework for measuring long-term behavior. As much a revolution in philosophy as an engineering text, Damage Tolerance and Durability of Material Systems postulates a new mechanistic philosophy and methodology for predicting the remaining strength and life of engineering material. This philosophy associates the local physical changes in material states and stress states caused by time-variable applied environments with global properties and performance.

There are three fundamental issues associated with the mechanical behavior of engineering materials and structures: their stiffness, strength, and life. Treating these issues from the standpoint of technical difficulty, time, and cost for characterization, and relationship to safety, reliability, liability, and economy, the authors explore such topics as:

• Damage tolerance and failure modes
• Factors that determine composite strength
• Micromechanical models of composite stiffness and strength
• Stiffness evolution
• Strength evolution during damage accumulation
• Non-uniform stress states
• Lifetime prediction

With a robust selection of example applications and case studies, this book takes a step toward the fulfillment of a vision of a future in which the prediction of physical properties from first principles will make possible the creation and application of new materials and material systems at a remarkable cost savings.

The papers from these proceedings address experimental and analytical methods for the characterization and analysis of modern composite and adhesive systems. They have been produced to provide understanding that can be used to design safe, reliable engineering components.

The application of composite materials to engineering components has spurred a ma jor effort to analyze such materials and the structures made from them. Most researchers workin in mechanics of composite structures understand that composite materials pro vide umque advantages but also present complex and challenging problems to researchers. The complex inelastic behavior and variety of failure modes of composite structures are a result of the strength and stiffness properties of constituents and their complex interac tions. Macromechanical constitutive models based on gross composite properties cannot realistically represent local interactions, and thus have serious limitations. The composite materials that are of most interest to engineering applications are often "brittle" in their behavior, in the sense that the strength and life of the material systems is controlled or greatly influenced by events or processes which involve volumes of material whose dimen sions are small compared to the global dimensions of the element. This is also true in ductile systems where local nonlinearity may contribute to local behavior which controls global response."

Composite material systems are the basis for much of the natural world around us and are rapidly becoming the basis for many modern engineering components. A controlling feature for the general use of such systems is their damage tolerance, durability and reliability. The present book is a comprehensive cross section of the state of the art in the field of the durability of polymer-based, composite, and adhesive systems. As such, it is of special value to researchers concerned with the frontier of the field, to students concerned with the substance of the subject, and to the applied community concerned with the finding methodologies that make it possible to design safe and durable engineering components using material systems.