缝合参数对复合材料T型接头拉脱承载能力的影响

利用二维平面应变模型对缝合增强试验件进行失效分析,采用内聚力模型模拟界面的破坏情况,通过在分层的上下界面加入非线性弹簧元来模拟缝线的增强作用,非线性弹簧元的力学性能(桥联律)由细观力学方法获得。有限元分析结果与试验值吻合较好。在此基础上,对缘条区的缝合增强进行缝线的材料、直径和缝合密度的参数化分析,研究各参数对T型接头拉脱承载能力的影响。结果表明:缝合可显著提高T型接头的拉脱承载能力,同时能使其在较大的加载位移下仍保持较高的承载性能。T型接头的拉脱承载能力随缝线直径和缝合密度的增大而增大,且直径和密度的影响显著。缝线的拉伸强度是影响缝线性能最主要的因素, T型接头的拉脱强度随缝线拉伸强度的升高而升高。T型接头的拉脱强度随缝线拉伸模量的降低而升高,但拉伸模量的影响较拉伸强度的影响小。 

Effects of parameters of stitching on pull-off carrying capacity of composite T-joint

Two-dimensional plane strain models were used to analyze the failure of stitched specimens. The interface failure condition was simulated with cohesive zone model, and the reinforcement effect of stitching was simulated with nonlinear spring elements inserted into the upper and lower interface of layer. The mechanical properties of the nonlinear spring elements (bridging law) were obtained based on micromechanical approach. The finite element analysis results agree well with test data. Based on the verified finite element model, the parametric analysis of stitching reinforcement in the flange area was done and parameters include the material, diameter of the stitch and density of stitching. The effects of parameters on pull-off carrying capacity of T-joint were studied. Results show that stitching can effectively improve the pull-off load capacity of T-joints and make the load capacity remain high under a large loading displacement. The pull-off load capacity of the T-joint increases as the diameter of stitch and density of stitching increase, and the influences of diameter and density are significant. The tensile strength of stitch is the main factor that affects the property of stitch and the pull-off strength of T-joint increases as the tensile strength of stitch increases, while the pull-off strength of T-joint increases as the tensile modulus of stitch decreases, but the influence of tensile modulus is not that significant of tensile strength.