U.S.-Federal Republic of Germany Cooperative Research on Phenomenological and Stochastic Viscoplasticity

该奖项支持伦斯勒理工学院的Erhard Krypl博士与德意志联邦共和国布伦斯韦格工业大学力学研究所的Elmar Steck博士在机械工程方面的合作研究。这两个机构的研究小组正在通过开发和测试材料在应力下的非弹性行为模型来研究粘塑性。虽然他们的理论有一些共同的特点，但他们基于完全不同的哲学或方法。美国的团队已经开发出一种基于超应力的现象学的、经过实验验证的粘塑性理论；西德的团队正在研究一种基于微观结构的随机理论。他们的合作旨在为唯象粘塑性理论提供微观结构基础，并将随机理论扩展到一维任意载荷和三维公式。RPI的优秀实验设施将用于测试新兴模型。现代材料和生产技术，加上经济需求，导致了各种机械设备的轻量化和日益苛刻的运行条件。预测材料在应力下的性能的简单分析方法已不再适用。结构材料的大多数极限状态与非线性、非弹性行为有关；只有在过去十年左右的时间里，随着复杂的计算技术的可用，才有可能对这种行为进行建模。通过对塑性研究的不同方法的分析和综合，可以进一步了解材料在应力作用下的行为，并改进材料模型。

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.