平行偏置裂纹相互作用及其合并条件  

Interaction between offset parallel cracks and combination conditions

作　　者：汪微微[1] 赵建平[1] 

机构地区：[1]南京工业大学机械与动力工程学院,江苏南京210009

出　　处：《南京工业大学学报（自然科学版）》2009年第4期27-31,共5页Journal of Nanjing Tech University(Natural Science Edition)

基　　金：国家高新技术研究发展计划(863计划)资助项目(2006AA04Z439);国家"十一五"科技支撑计划资助项目(2006BKA02B02)

摘　　要：裂纹之间的相互作用因其位置和方向的不同会引起应力场的相互增强或者相互减弱效应.运用FRANC2D软件,对单向拉伸载荷作用下含2条平行偏置裂纹的平板进行有限元分析,计算得到2条平行偏置裂纹在不同几何特征下的应力强度因子和应力变化图,再现了它们相互作用的应力场叠加规律,讨论了裂纹水平间距比(s/a2)、裂纹垂直间距比(h/a2)和裂纹长度比(a2/a1)对应力强度因子的影响以及2条裂纹之间的相互作用情况.结果表明:裂纹尖端内侧在s/a2=-1.4时所受的屏蔽效应最明显,h/a2对应力强度因子的影响因s/a2表现为3种不同的变化规律,且等大裂纹的相互作用最为显著.在此基础上验证了在用含缺陷压力容器安全评定(GB/T19624—2004)中关于非共面的两相邻穿透裂纹合并条件的适用性.The interaction between cracks could produce either an enhancement or a shielding effect on the stress field depending on positions and directions. By using the finite element software FRANC2D （Fracture Analysis Code 2D）, a plate specimen with two cracks of different geometric dimensions under cycling load was used as a model, the stress intensity factors and stress contours were calculated under offset parallel crack condition and the superposed rule of the stress of cracks field was also presented. The influence of different level interval ratio （s/a2 ） and vertical separation ratio （ h/a2 ）, crack length ratio （a2/a1 ） on stress intensity factors and the interaction of two cracks were discussed. Results indicated that the crack tip suffered the most conspicuous shielding effect at s/a2 = - 1.4, and h/a2 influence on stress intensity factors showed three different changing laws and the biggest interaction between cracks happened at two same ones. Based on these rules, the availability was verified with adjacent non-coplanar through thickness cracks in safety assessment for in-service pressure vessels containing defects.

关 键 词：平行偏置裂纹 应力强度因子 有限元 相互作用 合并条件 

分 类 号：TQ051[化学工程] O341.1[理学—固体力学]