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1報,主き裂の応力場を用いた近似解法

概要

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Recently, it has been reported that the fracture stress σ_f and the fracture toughness K_c of engineering ceramics, measured by use of short precracks, have values lower than, σ_f = K_<IC>/(πc)^<1/2> and K_C = K_<IC>, which might be expected from the conventional fracture mechanics. In the present study, assuming that these phenomena are due to the effect of a microdefect formed ahead of a main crack under applied stress, we propose a main crack-microdefect interaction model and formulate it using the theory of continuous distribution of dislocation in order to explain the above experimental results. As a result, we obtain the stress intensity factor K at the tip of the microdefect in a closed form. Supposing that macroscopic fracture would be caused when the stress intensity factor K reaches the plane-strain fracture toughness K_<IC>, we can obtain the analytical expressions of the fracture stress σ_f and the fracture toughness K_c and explain the above phenomena theoretically.
社団法人日本機械学会の論文
1993-10-25