材料非线性对复合材料层合板热自由边界效应的影响

本文用准三维有限元法研究了材料非线性对复合材料层合板热自山边界效应的影响,给出了修正型Hahn-Tsai非线性应力-应变关系的三维形式。由本文非线性分析方法得到的层间应力与以往由线性分析方法得到的层间应力做了比较,结果表明:材料非线性能显著降低层间剪应力的集中程度,但对层间正应力影响不太明显。

The Effect of Nonlinear Behaviour of Composite Material on the Interlaminar Stress Field in the Vicinity of Thermo-Free Edge Region of Composite Laminates

The utilization of composite laminates has greatly increased during the past decade, employed in structures as major components, especially in the aircraft industry. At the straight edges and at hole and cutout edges, called free edges, high values of interlaminar stresses are obtained in addition to the fact that locations are natureral stress raisers, that is because of the ply deformation mismatching caused by different fiber orientations and possibly different materials at the interface between adjacent plies. Therefore, interface failure, called delamination,could be a controlling failure mode and a major damage mode for composite laminates.The problem of the interlaminar stresses and de-lamination phenominon analysis of composite laminated components has been widely studied; especially for idealized linear response situation. However cornparetively little study has been made of nonlinear behaviour situation. The goal of the presented paper is to study the effect of nonlinear behaviour of composite materials en interlaminar stress field in the vicinity cf thermo-free edge region of ccmposite laminates. The 3D-modified Hahn-Tsai nonlinear constitutive mcdel for ccmposite laminae developed by authors and a Quasi-3D finite element scheme and approach are employed in interlaminar stress analysis. The numerical results for typical Pagano problem by using both of linear and nonlinear analysis are presented. The numerical results show that the nonlinear response of composite materials can significantly reduces the concentrated stress level and extent of interlaminar shear stresses in the vicinity of free edge cf composite laminates, but only slightly changes the concentrated level and extent of interlaminar normal stress.The conclusions will be enable researcher and analyst in the research field of mechanics of composite materials to get some better understanding of the nature of interlaminar stresses in the vinicity free edges of composite laminates. The project has been supported by the National Science Fund in China.