Cohesive Models of Fatigue Crack Growth and Stress-Corrosion Cracking

Citation

Nguyen, Olivier Thanh (2002) Cohesive Models of Fatigue Crack Growth and Stress-Corrosion Cracking. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/C3KP-4M44. https://resolver.caltech.edu/CaltechETD:etd-12032004-161201

Abstract

The aim of this dissertation was to develop models of fatigue crack growth and stress-corrosion cracking by investigating cohesive theories of fracture. These models were integrated in a finite-element framework embedding a contact algorithm and techniques of remeshing and adaptive meshing. For the fatigue model, we developed a phenomenological cohesive law which exhibits unloading-reloading hysteresis. This model qualitatively predicts fatigue crack growth rates in metals under constant amplitude regime for short and long cracks, as well as growth retardation due to overload. Quantitative predictions were obtained in the case of long cracks. We developed a chemistry-dependent cohesive law which serves as a basis for the stress-corrosion cracking model. In order to determine this cohesive law, two approaches, based on energy relaxation and the renormalization group, were used for coarse-graining interplanar potentials. We analyzed the cohesive behavior of a large--but finite--number of interatomic planes and found that the macroscopic cohesive law adopts a universal asymptotic form. The resulting stress-corrosion crack growth rates agreed well with those observed experimentally in 'static' fatigue tests given in the literature.

Thesis Files