When asked to start teaching a course on engineering fracture mechanics, I realized that a concise textbook, giving a general oversight of the field, did not exist. The explanation is undoubtedly that the subject is still in a stage of early development, and that the methodologies have still a very limited applicability. It is not possible to give rules for general application of fracture mechanics concepts. Yet our comprehension of cracking and fracture beha viour of materials and structures is steadily increasing. Further developments may be expected in the not too distant future, enabling useful prediction of fracture safety and fracture characteristics on the basis of advanced fracture mechanics procedures. The user of such advanced procedures m\lst have a general understanding of the elementary concepts, which are provided by this volume. Emphasis was placed on the practical application of fracture mechanics, but it was aimed to treat the subject in a way that may interest both metallurgists and engineers. For the latter, some general knowledge of fracture mechanisms and fracture criteria is indispensable for an apprecia­ tion of the limita tions of fracture mechanics. Therefore a general discussion is provided on fracture mechanisms, fracture criteria, and other metal­ lurgical aspects, without going into much detail. Numerous references are provided to enable a more detailed study of these subjects which are still in a stage of speculative treatment.

This book sterns from a course on Micromechanics that I started about fifteen years ago at Northwestern University. At that time, micro­ mechanics was a rather unfamiliar subject. Although I repeated the course every year, I was ne ver convinced that my notes have quite developed into a final manuscript because new topics emerged con­ stantly requiring revisions, and additions. I finally came to realize that if this is continued, then I will never complete the book to my total satisfaction. Meanwhile, T. Mori and I had coauthored a book in Micromechanics, published by Baifu-kan, Tokyo, in Japanese, entitled 1975. It received an extremely favorable response from students and researchers in Japan. This encouraged me to go ahead and publish my course notes in their latest version, as this book, which contains further development of the subject and is more comprehensive than the one published in Japanese. Micromechanics encompasses mechanics related to microstructures of materials. The method employed is a continuum theory of elasticity yet its applications cover a broad area relating to the mechanical behavior of materials: plasticity, fracture and fatigue, constitutive equa­ tions, composite materials, polycrystals, etc. These subjects are treated in this book by means of a powerful and unified method which is called the 'eigenstrain method. ' In particular, problems relating to inclusions and dislocations are most effectively analyzed by this method, and therefore, special emphasis is placed on these topics.

The fifth volume in this series is focused on the chemical and physical interactions between rocks undergoing metamorphism and the fluids that they generate and that pass through them. The recognition that such pro­ cesses can profoundly affect the course of metamorphism has resulted in a number of recent papers and we consider that it is time for a review by some of the interested parties. We hope our selection of contributors provides an adequate cross section and demonstrates some of the flavor of this rapidly developing field. A cursory examination of the volume will reveal that there are widely divergent opinions on the compositions of metamorphic fluids and on the ways in which they interact physically and chemically with the rocks through which they pass. Since our own views are extensively discussed in Chapters 4 and 8, we leave the reader to determine his own brand of the "truth. " We wish to thank D. Bird, S. Bohlen, D. Carmichael, G. Flowers, C. Foster, C. Graham, E. Perry, J. Selverstone, R. Tracy, J. Valley, and R. Wollast for their chapter reviews. Thanks are also due C. Cheverton for her editorial assistance, and the helpful staff at Springer-Verlag New York.