This award supports Dr. Erhard Krempl of Rensselaer Polytechnic Institute for collaborative research in mechanical engineering with Dr. Elmar Steck of the Institute of Mechanics at the Technical University of Braunschweig, Federal Republic of Germany. Research groups at both institutions are studying viscoplasticity by developing and testing models of the inelastic behavior of materials under stress. While their theories have some common characteristics, they are based on completely different philosophies or approaches. The U.S. group has developed a phenomenological, experimentally verified viscoplasticity theory based on overstress; the West German group is working on a stochastic, microstructurally based theory. Their collaboration is aimed at giving the phenomenological viscoplasticity theory a microstructural base and at extending the stochastic theory to arbitrary loading in one dimension and to a three-dimensional formulation. The excellent experimental facilities at RPI will be used to test the emerging models. Modern materials and production techniques together with economic demands have led to weight reduction and increasingly severe operating conditions for a great variety of mechanical equipment. Simple analytical methods for predicting performance of materials under stress are no longer adequate. Most limiting states of structural materials are associated with nonlinear, inelastic behavior; modeling such behavior has only become possible in the past decade or so with the availability of sophisticated computational techniques. Further understanding of material behavior under stress and improvement of material models can be expected from this analysis and synthesis of different approaches to the study of plasticity.
