PREFACE TO THE THIRD EDITION In recognition of rapidly changing developments in the field of mechanical behavior of solids, the third edition of this book covers many new topics with significantly broadened attention given to all structural materials, including metals, polymers, ceramics, and their respective composites. Most notably, a new chapter on the strengthening mechanisms in metals has been added along with extensive discussion of composites, which is treated and cross-referenced in eight chapters throughout the book. In addition, numerous topics introduced in earlier editions have been updated, with every chapter undergoing substantial change. A solutions manual for the chapter blems is available to qualified users. As before, special attention is given to providing the reader with many references for further study. A new supplementary reading list is also added to the end of several chapters. The current edition contains over 1100 references; of the more than 200 new listings, over 70%o represent citations published since the completion of the second edition in 1983. As such, this book should be viewed not only as a textbook for university study but also as a reference volume for professional use a major new section on composite materials was added to Chapter l and includes such topics as the isostrain analysis and the influence of fiber aspect ratio and orien tation on composite strength. Chapter 1 now also includes additional tables of me- chanical property data for ceramics and composites, an expanded discussion of strain rate effects on strength, and a section on classical failure theories (Tresca, Von Mises etc. ). The topic of partial dislocations has been moved from Chapter 3 to Chapter 2 and a new section on superlattice dislocations has been added to the discussion. Chapters 3 and 4 from the second edition have been combined into one chapter dealing with the slip and twinning response of crystalline solids; the topics of crys- allographic texturing and twinning have been condensed Chapter 4 represents a new addition to the book and is concerned with the strength- ening mechanisms in metals. Topics in this chapter include strain(work)hardening, grain-boundary strengthening, solid solution, precipitation, dispersion and martensitic strengthening, and metal-matrix composite strengthening. The section in Chapter 5 on materials for elevated temperature use has been expanded significantly to include a discussion of recent developments in cast and powder-produced conventional alloys, oxide-dispersion-strengthened mechanically alloyed systems, composites, and high- temperature coatings. Chapter 6 has been updated and includes new discussions designing with plastics (i.e, isochronous and isometric stress-strain curves), polymer composites, and expanded coverage of the strengthening of polymers Numerous changes and additions were also made to the second half of the book which examines the fracture mechanics of engineering materials. New sections on