This book contains the proceedings of a workshop on the Theoretical Founda tion for Large-Scale Computations of Nonlinear Material Behavior, held under the auspices of the National Science Foundation (NSF) and the Defense Advance Re search Projects Agency (DARPA), at Northwestern University, October 24-26, 1983. The main objective of this workshop was to provide a forum for the exchange of information and views on major issues relating to the fundamentals of character izing the inelastic constitutive material behavior. Comments on the Aims of the Workshop, by Drs. William Snowden and Thomas Bache, pp. 1-5, outline reasons for holding this workshop, and provide further background. The format of the workshop was designed to optimize the interaction between researchers whose primary interest is material characterization and numerical analysts whose primary interest is the development and practical use of large computer codes. The program of the workshop and a list of the workshop partic ipants are found at the end of these proceedings.

In this report we present a severe test of the effective stress and air-void porosity constitutive models by using them to simulate experiments in which small sale explosions were detonated in grout spheres. High quality reproducible particle velocity data were obtained from these experiments. We show that an effective stress law coupled with the irreversible collapse of air-filled porosity provide a very simple, straightforward explanation of this data. These results have served to reenforce our confidence in the validity of these models and their importance in determining seismic coupling. (Author).