抄録
The CED (crack energy density) in an arbitrary direction εφ, is expected to describe the fracture behaviors of a mixed mode crack. It was shown previously that εφ can be evaluated by a path-independent integral with sufficient accuracy for practical purpose. In this paper, as another evaluation method of εφ a method based on the relationship between εφ and load- displacement curves is discussed. The contents are as follows. 1) A relationship between initial crack lengths, load-displacement curves and εφ, which holds until cracks start to grow, is derived by considering the strain energies of the specimens with different initial crack lengths. A method of evaluating εφ from the load-displacement curves is proposed based on this relationship. 2) Based on this method, evaluation of εφ is attempted from load-displacement curves obtained by finite element analyses and also from experiments for specimens under tension with a crack inclined to the loading axis, and it is shown that this method is practical for evaluating εφ through comparison with the theoretical values and the values found by the path-independent integral.
