Abstract
Three point bend specimen with different ratio of K_<II> to K_I are used for ductile fracture tests. As the K_<II>/K_I, changes larger, the crack growth direction in mid-plane of the specimen curves to the loading point. Detailed observation of fracture surface is conducted, and it is shown that the average void diameter changes smaller as the K_<II>/K_I changes lager. Numerical simulation is also carried out using Gurson's yield function. In mixed-mode model, the crack propagates to the direction of loading point though the crack propagates straight in mode I model. The distribution of stress triaxiality around the crack tip is smaller in mixed-mode model than in mode I model. It can be guessed that voids diameter changes smaller as the K_<II>/K_I changes lager. The distribution of stress triaxiality corresponds with the dimple fracture zone qualitatively.
