Historically, a major problem for the study of the large deformation of crystalline solids has been the apparent lack of unity in experimentally determined stress-strain functions. The writer's discovery in 1949 of the unexpectedly high velocity of incremental loading waves in pre-stressed large deformation fields emphasized to him the pressing need for the independent, systematic experimental study of the subject, to provide a firm foundation upon which physically plausible theories for the finite deformation of crystalline solids could be constructed. Such a study undertaken by the writer at that time and continued uninterruptedly to the present, led in 1956 to the development of the diffraction grating experiment which permitted, for the first time, the optically accurate determination of the strain-time detail of non-linear finite amplitude wave fronts propagating into crystalline solids whose prior history was precisely known. These experimental diffraction grating studies during the past decade have led to the discovery that the uniaxial stress-strain functions of 27 crystalline solids are unified in a single, generalized stress-strain function which is described, much of it hitherto unpublished, in the present monograph. The detailed study of over 2,000 polycrystal and single crystal uni axial stress experiments in 27 crystalline solids, in terms of the variation of a large number of pertinent parameters, has provided new unified pat terns of understanding which, it is hoped, will be of interest and value to theorists and experimentalists alike.

This volume collects papers dedicated to Jerry Ericksen on his sixtieth birthday, December 20, 1984. They first appeared in Volumes 82-90 (1983-1985) of the Archive for Rational Mechanics and Analysis. At the request of the Editors the list of authors to be invited was drawn up by C. M. Dafermos, D. D. Joseph, and F. M. Leslie. The breadth and depth of the works here reprinted reflect the corresponding qualities in Jerry Ericksen's research, teaching, scholarship, and inspiration. His interests and expertness center upon the mechanics of materials and extend to everything that may contribute to it: pure analysis, algebra, geometry, through all aspects of theoretical mechanics to fundamental experiment, all of these illumi nated by an intimate and deep familiarity with the sources, even very old ones. He is independent of school and contemptuous of party spirit; his generosity in giving away his ideas is renowned, but not everyone is capable of accepting what is offered. His writings are totally free of broad claims and attributions beyond his own study. Some are decisive, some are prophetic, and all are forthright. His work has served as a beacon of insight and simple honesty in an age of ever more trivial and corrupt science. The authors of the memoirs in this volume are his students, colleagues, admirers, and (above all) his friends.

An adequate physical and mathematical description of material be havior is basic to all engineering applications. Fortunately, many prob lems may be treated entirely within the framework of elastic material response. While even these problems may become yuite complex be cause of geometrical and loading conditions, the linearity, reversibility, and rate independence generally applicable to elastic material descrip tion certainly eases the task of the analyst. Today, however, we are in creasingly confronted with practical problems which involve material response which is inelastic, hysteretic and rate dependent combined with loading which is transient in nature. These problems include, for instance, structural response to moving or impulsive loads, all the areas of ballistics (internal, external and terminal), contact stresses under high speed bearings, high speed machining, rolling and other metal working processes, explosive and impact forming, shock attenuation structures, seismic wave propagation, and many others of equal im portance. As these problems were encountered, it became increasingly evident that we did not have at hand the physical or mathematical description of the behavior of materials necessary to produce realistic solutions. Thus, during the last ten years particularly, there has been considerable effort expended toward the generation of both experi mental data on the dynamic mechanical response of materials as well as the formulation of realistic constitutive theories. It was the purpose of the Symposium at which the articles in this book were presented to discuss and review recent developments in this field.