纯Ⅱ型载荷作用下裂纹的三维厚度效应研究  

THICKNESS EFFECTS ON THE CRACK TIP FIELDS UNDER MODE Ⅱ LOADING

作　　者：徐绯[1] 李玉龙[1] 郭万林[2] 

机构地区：[1]西北工业大学飞机系强度研究所,西安710072 [2]南京航空航天大学航空宇航学院,南京210016

出　　处：《机械强度》2003年第5期561-567,共7页Journal of Mechanical Strength

基　　金：国家自然科学基金 (中物院联合基金 ) (1 0 2 760 33);西北工业大学"英才计划"项目;黄玉珊先生基金资助项目~~

摘　　要：采用修正的边界层模型 ,利用有限元计算方法对纯Ⅱ型裂纹的厚度效应进行分析和研究 ,通过比较三维裂纹纯Ⅰ型和纯Ⅱ型裂纹尖端的应力、应变以及J积分和裂尖张开位移等参数 ,得到纯Ⅱ型载荷作用下厚度效应影响弱的认识。与Ⅰ型结果相比可以看出 ,在Ⅱ型载荷作用下裂尖的应力、应变场的厚度效应不明显 ,但三维影响区的大小与Ⅰ型基本相同 ,在裂尖前方半厚度以内存在着很强的三维效应区 ,从半厚度到 1.5倍厚度范围应力在不同的厚度位置有显著的变化 ,在 1.5倍厚度以外的区域表现为平面应力场的特性。在纯Ⅱ型载荷的作用下 ,三维J积分Jlocal沿厚度分布不随载荷变化 ,且基本没有厚度效应 ,裂尖滑动位移 (cracktipslidingdisplacement ,CTSD)也没有厚度效应 ;沿不同厚度截面Jlocal积分和CTSD存在线性关系。The thickness effects on the crack tip fields under mode Ⅱ loading are carefully analyzed using the modified boundary layer model by FEM simulation. Comparing with the crack tip fields under mode Ⅰ loading, the thickness effect on the mode Ⅱ loading is very weak. Under pure mode Ⅱ case, the distributions of the stress and strain on the mid-plane and on the surface plane are almost the same, except for those at the perpendicular direction of the crack line. The three-dimensional zone under mode Ⅱ loading is the same as that under mode Ⅰ loading, which is most strong inside the region r/t<0.5 while disappears outside the region r/t>1.5. Here t is the plate thickness. Three main conclusions about J local integral and crack tip displacements are obtained from the discussion. ① The three-dimensional J local integral has no thickness effects under mode Ⅱ loading. ② The crack tip opening displacement (CTOD) for mode Ⅰ and crack tip sliding displacement (CTSD) for mode Ⅱ have very weak thickness effect. ③ J local integrals are linear with CTOD and CTSD at different thickness plane under both mode Ⅰ and mode Ⅱ loadings.

关 键 词：Ⅱ型裂纹 厚度效应 三维分析 裂尖场 J积分 裂尖位移量 

分 类 号：O346.1[理学—固体力学]