US-Federal Republic of Germany Cooperative Research: Probabilistic Description of Creep Damage and Failure

该奖项支持利哈伊大学的Terry J.Delph教授对西德弗莱堡的弗劳恩霍夫材料力学研究所进行长期研究访问，在那里他将主要与高温材料系主任Hermann Riedel博士合作。这项研究的目的是扩展Riedel博士最近开发的高温蠕变损伤和失效的确定性模型，以包括各种概率特征。他们对蠕变损伤的随机增长和随机蠕变失效时间等特征感兴趣。方法的主要途径包括随机微分方程组的积分技术和由Coleman提出的失效时间分布的一般表达式。随着对更高功率和效率的驱动导致能量转换设备的工作温度更高，在较低温度下被抑制或不明显的结构失效模式变得更加重要。蠕变断裂是能量转换装置最重要的高温失效模式之一。拟议的研究将提供基于物理和概率的蠕变损伤过程的描述；也就是说，它将能够预测在给定时间t的失效概率。这将产生比当前确定性模型更有用的结构可靠性估计。

This award supports Professor Terry J. Delph of Lehigh University for a long term research visit to the Fraunhofer Institute for Material Mechanics in Freiburg, West Germany, where he will work primarily with Dr. Hermann Riedel, head of the High Temperature Materials Department. The goal of this research is to extend a deterministic model for high-temperature creep damage and failure recently developed by Dr. Riedel to include various probabilistic features. They are interested in features such as random growth of creep damage and random creep failure times. The principal avenues of approach include integration techniques for stochastic differential equations and a general expression for the distribution of failure times developed by Coleman. As the drive for increased power and efficiency leads to higher operating temperatures for energy conversion devices, structure failure modes which were either suppressed or not apparant at lower temperatures become of greater importance. One of the most significant high-temperature failure modes in energy conversion devices is creep rupture. The proposed research will provide a description of the creep damage process that is both physically and probabilistically based; that is, it will be capable of predicting the probability of failure by a given time "t." This will produce much more useful estimations of structural reliability than current deterministic models.