黒鉛材料の遅れ破壊の機構に関する一考察

概要

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A mechanism of delayed fracture under static load was proposed for fine prained nuclear grade isotropic graphite. Rectangular specimens were loaded in 3-point bending mode to the neighbourhood of the fracture stress and kept at about the same stress level by using an Instron type testing machine. The discrete acoustic emission (AE) signal were generated before the specimen completely fractured. This fact indicates that microcracks are produced or propagate discontinuously within the specimen under static load. This phenomenon was explained by a model in which the microstructure of graphite is regarded as the combination of elastic and plastic parts. According to the model, the stress relaxation in the plastic part induces an increase in stress at the rergion of crack tips or some kinds of defects in the elastic part.
社団法人日本材料学会の論文
1985-12-15