界面破坏对割口单向叠层板的应力集中及强度的影响

THE INFLUENCE OF INTERFACIAL FAILURE ON THE STRESS CONCENTRATIONS AND STRENGTHS FOR NOTCHED UNIDIRECTIONAL LAMINATES

基于剪滞理论,建立一种计及界面损伤的分层剪滞模型,分析了含割口的单向叠层板在拉伸荷载作用下的应力重新分布问题,据此可求得界面损伤区长度和割口前缘完整纤维的应力集中因子。在此基础上,采用细观统计破坏理论,研究了割口单向叠层板的拉伸破坏机理和强度,定量获得了残余拉伸强度与界面剪切强度的关系,所得结果与现有实验吻合较好。结果表明,应力集中和强度与割口长度及界面剪切强度有关;适宜的界面黏结,具有较高的残余拉伸强度。

Based on the shear-lag theory,a layering shear-lag model taking into account the interfacial damage was proposed and the stress redistributions for notched unidirectional laminates under tension were analyzed,from which both the length of interfacial damage area and stress concentration factors in intact fibers at root of the notch were obtained.On the basis of the knowledge of these stress redistributions,the tensile failure mechanism and strengths of notched unidirectional laminates were studied by using a micro-statistical fracture theory.Consequently the relation between residual tensile strength and interfacial shear strength was obtained quantitatively.The present results have a good agreement with the existing experiment and show that both the stress concentration and strength are related to the interfacial shear strength,the residual tensile strength is relatively high when the interfacial cohesion is appropriate.