応力分布下の平滑表面における応力腐食割れのモンテカルロ・シミュレーション

概要

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A Monte Carlo simulation model for the process of stress corrosion cracking (SCC) in structural metal materials under non-uniform stress condition has been proposed. The possible number of crack initiations is set for a given space and initiation times for all cracks are assigned by random numbers based on exponential distributions depending on stress level. Sites and lengths of the cracks are assigned by random numbers based on uniform distribution and normal distribution, respectively. Coalescence of cracks and subcritical crack growth are determined based on the fracture mechanics concept. Through the SCC process in the model, the influence of semi-elliptical surface cracks is taken into consideration. SCC simulations were carried out on a smooth surface under two kinds of non-uniform stress conditions such as residual stress distribution around a weld line. Multiple parallel cracks and multiple cracks along narrow high stress region were obtained depending on the stress distributions, respectively. Simulation results exhibit the applicability of the model to describe the SCC behavior observed in real structures.