主き裂前方にある微小欠陥が強度に及ぼす影響について : 第2報,主き裂-微小欠陥相互作用モデルの厳密解

抄録

In the previous paper, an approximate solution to the main crack-microdefect interaction model was derived using a main crack stress field, and the effect of a microdefect ahead of a main crack on the strength of solids was discussed in terms of the model. In the present paper, in order to investigate more precisely the above effect, the main crack-microdefect interaction model is formulated more specifically based on the continuous distribution theory of dislocations, and the distribution functions for both a main crack and a microdefect are obtained. As a result, we obtain stress intensity factor K both at the tip of a main crack and at a microdefect in a closed form. Using these K values, we can elucidate the effective range of the above interaction model and the crack shielding effect by a microdefect. Furthermore, the crack length dependence of fracture stress and fracture toughness of engineering ceramics can be explained well theoretically using the present model.