考虑约束效应的概率断裂失效分析  

Influence of constraint effects on fracture failure probability

作　　者：王钟羡[1] 王惠剑[1] 吴春笃[2] 

机构地区：[1]江苏大学理学院,江苏镇江212013 [2]扬州环境资源职业技术学院,江苏扬州225127

出　　处：《江苏大学学报（自然科学版）》2010年第4期478-482,共5页Journal of Jiangsu University：Natural Science Edition

基　　金：国家"863"计划项目(2008AA100905)

摘　　要：针对试样几何、加载方式会在裂纹尖端产生不同的约束效应,对存在缺陷的构件进行安全性评定、寿命评估和失效概率计算时考虑约束效应,在R6失效评定曲线基础上,采用T-应力作为约束参量,建立与约束相关的失效评定曲线.在单向和双向载荷情况下,利用Mont-carlo法对存在半椭圆形表面裂纹的构件进行概率断裂力学分析,并与由传统R6失效评定曲线得到的结果进行比较.在不同的双向载荷比和裂纹几何情况下,讨论约束效应对裂纹失效概率和失效点位置预测结果的影响程度.结果表明,裂纹尖端的约束效应对构件断裂失效概率和起裂点位置均具有较大的影响;载荷比越大,由两种评定曲线计算得到的失效概率越接近.Crack geometry and loading form can make different constraint effects at the crack tip field. The influence of the constraint must be taken into account for the structure integrate assessment, life assessment and failure probability calculation. In this study, T stress was introduced to describe the constraint effect. According to the stress intensity factor expression and the T- stress expression of the surface crack, and considering the influence of biaxial loading effects, a modified failure assessment curve was established. The constraint effect was related to the crack tip field. Through the example of the component containing a semi-elliptical surface crack, the failure probability results based on the traditional R6 failure assessment curve and the modified failure assessment curve considering the constraint effect were compared. The varieties of the failure probability and the failure position along the crack front were discussed with the different crack geometry and the different biaxial loading ratio. It shows that the constraint effect at the crack tip field has an important influence on the failure probability and the failure initial position.

关 键 词：表面裂纹 失效概率 失效评定曲线 约束效应 T-应力 双向载荷 

分 类 号：O346.1[理学—固体力学]