管道环向裂纹在简单加载下的撕裂失稳与塑性失稳研究

STUDY ON TEARING INSTABILITY AND PLASTIC COLLAPSE UNDER SIMPLE LOADING FOR CIRCUMFENTIAL CRACKS OF PIPES

摘要: 本文建立了管道环向贯穿裂纹在简单加载下撕裂失稳与塑性失稳应力的近似关系式,研究结果表明:对于管道环向贯穿裂纹,其在简单拉伸下的撕裂失稳与塑性失稳的应力比,和在纯弯加载下的斯裂失稳与塑性失稳的应力比,近似相等,即:σ_ins,s/σ_l,s ≌ σ_{ins þ}/σ_{l þ};并已通过实际裂纹构形的具体评定计算,得到证实。根据管道环向贯穿裂纹与表面裂纹有相似的加载模式和相近的破坏机制,上述结论可以推广应用于管道环向表面裂纹,其精度满足工程评定要求,对于管道环向表面裂纹 J 积分近似表达式的建立,将起到重要作用。

Abstract: In this paper, authors established the approximate relative expression of tearing instability stress and plastic collapse stress under simple loading for circumferential throughwall cracks in pipes. Based on the relative expression, the equation (σ_ins,s/σ_l,s) ≌ (σ_{ins þ}/σ_{l þ}) was obtained which possesses sufficient Precision in engineering assessment and can be extended to circumferential part-throughwall flaws subjected to Pure bending or combined tension and bending.