Modeling Fatigue

Kristine Cochran, University of Illinois at Urbana-Champaign

Fatigue may lead to structural failure under repetitive, though relatively low loading, by causing crack growth. Plasticity induced crack closure (PICC) is a phenomenon of fatigue cracks in which the extent of yielding at the crack tip affects the growth rate of a crack undergoing cyclic loading. Numerous factors including the type of material, the geometry of the structure, and the nature of the loading influence the physical process of material yielding. Computational modeling is essential for gaining insights into this complicated phenomenon and for developing engineering criteria for real structures. The finite element method has been the tool of choice for modeling PICC in fatigue cracks, with the community of fatigue researchers compiling recommendations and results over the previous 30 years. Computational limitations of the past led to substantial simplifications in the modeling of crack growth including the spatial resolution of the crack and the complexity of the material behavior. As computational resources improve and allow models to increase in complexity, new issues are surfacing which throw doubt upon the old results and recommendations. This talk discusses the conflicts observed between recent models using enhanced mesh refinement and material fidelity with previous findings produced using generally accepted techniques.

Abstract Author(s): Kristine Cochran