复合材料层合板剪切稳定性试验及强度预测

对无损伤及含冲击损伤的复合材料层合板进行了剪切稳定性试验，基于数字图像相关方法 (Digital image correlation,DIC)对层合板屈曲后屈曲行为进行了实时测量。试验结果表明：引入冲击损伤后，复合材料层合板剪切屈曲波形、屈曲载荷无明显变化，失效模式转变，承载能力下降了9.69%。随后，基于断裂面失效理论，建立了考虑剪切非线性效应的复合材料渐进损伤失效模型，并对复合材料层合板剪切失效过程进行了模拟。模型采用软化夹杂法将冲击损伤等效简化，直接将损伤区的几何边界信息写入材料模型中，不需要对冲击损伤区进行切割，从而保证了整体网格质量。与试验结果对比发现：模型考虑剪切非线性对屈曲载荷预测无明显影响，对后屈曲承载能力的预测精度影响较大，不考虑剪切非线性效应时的误差可达20%以上；软化夹杂法可以有效地模拟冲击损伤，预测的含冲击损伤的复合材料层合板的屈曲载荷、破坏载荷误差分别为-3.17%、-1.27%。

Shear stability test and strength prediction of composite laminates

The shear stability tests of composite laminates without damage and with impact damage were carried out. The post buckling behavior of composite laminates was measured in real time based on digital image correlation (DIC). The test results show that after the introduction of impact damage, the shear buckling waveform and buckling load of composite laminates do not change significantly, and the failure mode changes, the bearing capacity decreased by 9.69%. Then, based on the fracture surface failure theory, a progressive damage failure model of composite materials considering shear nonlinear effect was established, and the shear failure process of composite laminates was simulated. The softened inclusion method was used to simplify the impact damage, and the geometric boundary information of the damage area was directly written into the material model. There was no need to cut the impact damage area, so as to ensure the overall grid quality. Compared with the experimental results, it is found that the model considering shear nonlinearity has no obvious influence on the prediction of buckling load, and has a great influence on the prediction accuracy of post buckling capacity. The error without considering shear nonlinearity can reach more than 20%; The softened inclusion method can effectively simulate the impact damage. The predicted buckling load and failure load errors of composite laminates with impact damage are ?3.17% and ?1.27% respectively.