ワイブル応力を用いた脆性破壊評価結果におよぼす亀裂先端要素の影響に関する分析

抄録

Weibull stress based on the local approach has been proposed as a fracture evaluation method considering the effect of plastic constraint at the crack front, and its effectiveness has been shown in the past studies. On the other hand, when the shape parameter m which is used in Weibull stress becomes large, it may lead the error peculiar to the finite element analysis results at the crack front.

In this study, the shape parameter m of the Weibull stress σ_W was obtained for evaluating the fracture toughness of low alloy steel for pressure vessels, and the influence of the element dividing condition at the crack front was investigated. Under the element dividing condition which does not impact on the Weibull stress evaluation results, the shape parameter m showed a large value exceeding 100. However, by finely dividing the element in tangent direction at the crack front, it was confirmed that the shape parameter m fell within the range of normal values of structural steels.