抄録
The behavior of ductile crack initiation from a notch and a crack under mode I loading has been investigated on a structural steel, SM 41 A. Experiments and large deformation finite element analyses based on Gurson's yield function were carried out for three-point-bending specimens with a notch or a crack. In the notched specimens, void growth behavior around the notch tip is described by the void volume fraction obtained by the finite element analysis, and the ductile crack initiation can be predicted based on the concept of critical void volume fraction. In the finite element analysis of the cracked specimen, a large strain field - process zone- around the crack tip is characterized by the void volume fraction. From the comparison of experimental results with analytical results, it is suggested that, in order to predict the ductile crack initiation from a crack based on the concept of critical void volume fraction, the correlation between the size of large strain field and the spatial distribution of inclusions should be taken into consideration.
