Plasticity-induced crack closure from surface to deep interior locations - A three-dimensional finite element study

The remeshing technique has been proved to be useful in saving numerous elements for two-dimensional finite element crack closure analysis. The computer code employing this technique was further developed for three-dimensional problems. Using this technique, the crack closure phenomenon of specimens with various thicknesses was studied, with emphases on the closure transition from specimen surface to deep interior locations. It was found that, at the specimen surface, the loading-direction stress distribution, and the crack tip plastic zone differ from those obtained under plane stress condition. However, the surface and the plane stress opening stresses are close. When a specimen is thick enough, the stress state, plastic zone and crack opening stresses at the deep interior locations are close to those under plane strain condition. The surface effects on crack opening behavior reach to a depth that is approximately 1.34 times of the Irwin's plane stress plastic zone size.