Microstructural Short Fatigue Crack Growth ― Effect of Mixed Mode Conditions and Crack Closure

摘要

A slip band crack model based on the boundary element technique is proposed to simulate fatigue crack growth in stage Ⅰ. The model is based on a yield strip model analogously to that of Bilby et al. [1 ] and extended in such a way, that the crack is allowed to glide along the ligament and to open simultaneously. Therefore, roughness-induced crack closure can be included and due to a numerical approach no restrictions on slip band geometry are required. An easy but efficient solution procedure to solve the system of equations obtained from the model is presented. The simulation of a crack in a jagged slip band shows the high influence of roughness-induced crack closure. The retardation of the crack increases with decreasing inclination angle of the slip band. A comparison of the simulation with measured short crack data shows the practical importance of crack closure effects and verifies the simulation procedure.