FEM study of fatigue crack closure under double slip

An elastic-plastic finite element analysis of Mode I crack growth and plasticity induced crack closure is presented. The simulation, which models crack tip plasticity using two slip planes, predicts slip patterns experimentally observed in real crystals or grains. The model shows that plasticity induced crack closure will occur when the crack tip plastic zone is smaller than the grain size. Closure levels are found to vary as the crystallographic orientation of the model with respect to the crack line is changed. For some orientations the closure levels are found to be negligible, while in others the levels approach 0.35 of the maximum applied load. Closure levels also vary as the angle between the slip planes is varied. The values span a similar range. The amount of crack closure for any particular crystallographic orientation and/or slip plane configuration is found to be a balance between several variables. Primarily, the closure levels are dictated by the magnitude of the static crack opening displacement and amount of residual plasticity along the crack line. Copyright © 1996 Acta Metallurgica Inc.

Duke Scholars

Author Ken Gall Thomas Lord Department of Mechanical Engineering and Materia ...