Three-point bending test investigation and numerical analyses of composite stiffened panels with “ex-situ” toughen
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摘要: 为研究离位增韧对复合材料加筋板结构承载性能的影响，首先，分别对未离位增韧和离位增韧复合材料帽型长桁加筋板进行了三点弯曲试验，比较了2种加筋板的初始分层载荷、极限载荷以及试验现象；然后，利用ABAQUS建立了三维渐进失效模型，考虑长桁-蒙皮界面和复合材料层合板的失效，对界面的分层机制和蒙皮的失效过程进行了分析。结果表明：有限元结果与试验结果吻合较好，离位增韧仅能略微提高界面的初始分层载荷，但对极限载荷有较大提升；在分层起始阶段I型拉伸模式占主要作用，随着分层不断扩展，II型剪切模式占比持续增加，而剪切模式的高韧性正是离位增韧界面具有良好性能的重要原因。所得结论表明离位增韧界面有良好的抗剥离性能，且在剪切方向上的表现尤为突出。Abstract: In order to investigate the effects of "ex-situ" toughened on the structural bearing capacities of composite stiffened panels, three point bending tests were conducted on composite omega stiffened panels without "ex-situ" toughen and with "ex-situ" toughen firstly, and the initial debonding load, critical failure load and the phenomenon of tests for the two kinds of stiffened panels were compared. Then, three-dimensional progressive failure model was established using ABAQUS, and the mechanisms of interface delamination and the failure process of the skins were analyzed considering the failure of stringer-skin interface and laminated composite plates. The results show that the finite element results coincides well with the test results, "ex-situ" toughen can only improve the initial debonding load of the interface slightly, but has relatively obvious improvement on critical failure load. At the beginning stage of delamination, the type I tensile mode plays a major role. With the delamination expanding continuously, the proportion of type II shear mode increases constantly, while the high toughness of shear mode is the significant cause for the outstanding performances of "ex-situ" toughened interface. The conclusions obtained show that "ex-situ" toughened interface has favorable delaminating resistance, and the behaviour on shear direction is particularly outstanding.
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