奇异薄层单元及其在双材料界面断裂分析中的应用  

SINGULAR THIN-LAYER ELEMENT AND ITS APPLICATION IN BI-MATERIAL INTERFACE FRACTURE ANALYSIS

作　　者：沈辉[1] 周储伟[1] 

机构地区：[1]f南京航空航天大学机械结构力学及控制国家重点实验室,南京210016

出　　处：《工程力学》2012年第10期69-74,共6页Engineering Mechanics

基　　金：国家自然科学基金项目(10772078,10472045)

摘　　要：构造了一种平面应力奇异薄层单元并证明了其具有-1/2阶奇异性。用此单元研究了双材料界面层的刚度对界面裂纹尖端场的影响。研究发现:对于I型界面断裂,减小界面法向刚度对KI、KII的影响远大于减小界面切向刚度,且法向和切向刚度的减小对KII的影响均大于对KI的影响,降低法向刚度会显著改变裂尖正应力和剪应力的分布,而降低切向刚度只明显改变剪应力的分布,对正应力的分布影响不大;对于界面II型断裂,则减小切向刚度对KI、KII的影响远大于减小法向刚度,且切向、法向刚度的减小对KI影响均大于对KII影响,降低切向刚度会显著改变裂尖正应力和剪应力的分布,而降低法向刚度只明显改变裂尖正应力的分布,对剪应力的分布影响不大。随着界面刚度增大,应力强度因子和裂尖应力分布均趋近无厚度理想界面情况。A stress singular thin-layer element was developed and its-1/2 singularity was proved.Then the element was adopted to study the effects of interface stiffness on the crack tip field of a bi-material interface crack.The results demonstrate that for mode I interface fracture,the decreasing of normal interface stiffness will introduce more significant variations of stress intensity factors KI and KII than the decreasing of shear interface stiffness.It also causes notable changes of both normal and shear stress components at a crack tip.However,decreasing shear stiffness only affects the shear stress component notably.In this fracture model,effects of reducing either normal or shear stiffness on KII are more marked than on KI.On the contrary,for model II interface fracture,shear stiffness becomes the dominator on the two stress intensity factors and both normal and shear stress components vary greatly with its decreasing.Reducing normal interface stiffness just remarkably affects normal stress component other than all the stress components.In this case,KI is more sensitive to the two interface stiffness parameters than KII.For any fracture model,stress intensity factors and stress concentrations at a crack tip approach to those of no thickness perfect interface when interface stiffness of bi-material increase.

关 键 词：奇异薄层单元 双材料 界面断裂 应力强度因子 应力集中 

分 类 号：O346.1[理学—固体力学]