内压圆筒内外表面裂纹交互应力强度因子分析

SIF of interaction of internal and external surface cracks in a pressurized cylinder

对内压圆筒内外表面两个相同表面裂纹交互应力强度因子进行了综合分析,分析的裂纹深度与长度比为:b/a为0.25,0.5,0.75,1.0;裂纹深度与圆筒壁厚比为:2b/t为0.2,0.4,0.6,0.7,0.8。数值结果显示,当2b/t<0.7时,与单个裂纹相比,交互作用使得内外表面裂纹应力强度因子均减小。因而,对于实际的断裂分析,可不考虑交互作用,而将得到偏保守的结果。

This paper presents a comprehensive range of analysis on the interaction of two identical semi-elliptical surface cracks at the internal and external surfaces of a pressurized cylinder. The considered ratios of the crack depth to crack length are \$b/a=0.25\$, \{05\}, \{075\} and 1.0; the ratios of the crack depth to wall thickness of the cylinder are \$2b/t=\{0.2,\}\$ \{0.4\}, \{0.6\}, \{0.7\} and \{0.8\}. The numerical results show that for \$2b/t<0.7\$, the interaction leads to a decrease in the stress intensity factors for both internal and external surface cracks, compared with a single internal or external surface crack. Thus for fracture analysis of a practical pressurized cylinder with two identical semi-elliptical surface cracks at its internal and external surfaces, a conservative result is obtained by ignoring the interaction.