Search Results

Time dependent mechanical breakdown of materials has been a long-standing concern for structural components, and it is especially exacerbated by randomness in material properties, loading conditions, and other sources of uncertainty. A generalized phenomenological cumulative distribution function for lifetime, which is consistent with fundamentals of reliability theory, is presented. The form of the cdf includes a kernel that incorporates functions for time dependent loading, mechanical breakdown, and statistical behavior. The formalism is applicable for a variety of loading conditions including creep rupture, rate dependent tensile loading, and fatigue. Analysis of failure under stress histories such as variable stress amplitude or step-stress loadings is manageable as well. The model is a generalization of the classical accelerated life model in which covariates are included to account for physical attributes that directly influence component lifetime.