Study on the Fatigue Crack Growth Problem under Mode Ⅰ+Ⅱ Mixed Mode Condition with Elastic-Plastic Deformation

摘要

The fatigue crack growth test under mode Ⅱ dominant condition is conducted. It is found that the crack growth direction can not be predicted by the conventional method. By the fracture surface observation, it is also found that the thickness effect strongly affects this behavior. Three dimensional elastic-plastic FEM analyses are conducted for this problem considering the Bauschinger effect. The change of the crack tip stress field during fatigue crack growth is studied. The criteria to predict the fatigue crack growth direction are studied and new criteria are discussed.