Crack Energy Density in an Arbitrary Direction and Load-displacement Curves

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