用于压力容器评定的等K及等δ换算方法

Equivalent K Conversion and Equivalentδ Conversion in Defect Assessment of Pressure Vessel

在压力容器缺陷评定标准中对埋藏和表面三维裂纹问题的处理,通常采用半经验的等应力强度因子(K)换算方法。本文提出采用能够反映弹塑性断裂实际特性的参数裂纹张开位移(δ)代替应力强度因子(K),并以圆盘裂纹为例,对等K及等δ换算进行了论证。结果表明:弹塑性状态下等K换算偏于保守,等δ换算比等K换算更加合理适用。

Up till now, in the defect assessment standard of pressure vessel, a semi-experience method, equivalent K （stress intensity factor） conversion, usually used to deal with beried and surface three dimensional crack .In this paper, the method using elastic-plastic fracture parameter δ （crack tip opening displacement） to replace K（stress intensity factor） is first proposed, and equivalent K conversion in usual pressure vessel assessment is replaced by equivalent δ conversion, and equivalent K conversion and equivalent δ conversion is demonstrated in penny shaped crack .It is observed that the equivalent K conversion is conservative, and the equivalent δ conversion is more reasonable than the equivalent K conversion.