等長並列 line crack を有する材の変形挙動

概要

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The characteristics of brittle fracture and fatigue failure in the body which has several cracks and defects being close to each other, are different from those in the body having single crack due to the interaction. For the plate containing parallel cracks of equal length, it is reported recently that not only the brittle fracture stress but also the critical COD are larger than those for the plate containing single crack and increase with decrease of distance of parallel cracks. Accordingly, the COD concept is not simply applicable to that case. In this report, deformation behaviors such as stress, strain, plastic zone size ahead of crack tip and COD in the plate containing two parallel equal length cracks under uniaxial tension are investigated by the elastic-plastic analysis based on the finite element method and the experiment. Main results obtained are as follows : COD of parallel cracks under same load decrease with decrease of distance of cracks. When COD is constant, magnitudes and distributions of stress σ_y and strain ε_y in tensile direction around crack tip are much the same regardless of distance of cracks and yet distributions of σ_x differ with distance of cracks. Moreover, it is shown that the parameter with respect to the brittle fracture initiation may possibly exist which is dependent on triaxiality of stress around crack tip.
社団法人溶接学会の論文
1975-03-05