S042022 変動負荷速度下におけるセラミックスの動的疲労強度分布特性と破壊メカニズム([S04202]セラミックスおよびセラミックス系複合材料(2))

Abstract

This paper presents probabilistic approach for estimating the dynamic fatigue strength inceramics under variable stress rate. First, a probabilistic model was proposed on the basis of the slow crack growth concept in conjunction with two-parameter Weibull distribution. Second, the four-point bending test was carried out for alumina ceramics under two-step stress rate at room temperature. The experiment result was compared with the predictions to verify the validity of the model. The fracture surface of the specimen after the bending test was also observed. It is seen that mirror, mist and hackle in the vicinity of the surface acting maximum stress. Therefore, the dynamic fatigue fractures under variable stress rate caused by slow crack growth from an initial crack. We constructed fracture probability - bending strength diagrams (F-S diagrams) with the experimental results using the model. The F-S diagrams were in good agreement with Weibull plots of the bending strength.