复合材料层压板低速冲击响应尺度效应数值模拟研究

为了研究尺度效应对于复合材料层压板在低速冲击作用下的动态响应和冲击损伤的影响，基于相似理论，建立了三种不同尺寸的层压板受冲击的三维有限元模型。在该模型中，针对层压板的面内损伤，采用改进的Chang-Chang准则进行预测；针对层压板内层间分层损伤，则使用Cohesive界面单元进行模拟。一旦复合材料层压板在低速冲击作用下产生损伤，则对出现损伤的区域进行材料参数退化。采用该模型对三种不同尺寸的层压板的冲击过程进行有限元分析，并将不同冲击速度下的冲击响应进行比较，得出了如下结论：在层压板内未发生冲击损伤时，冲击产生的挠度和冲击力与相似理论解十分吻合，一旦出现冲击损伤，则冲击力的变化与相似理论解有所差别；如果两个缩放模型的冲击速度之比等于缩放比例的平方根，则两个模型中的相对分层尺寸基本是相同的，这个结果与已有的实验结果吻合；而对冲击后面内损伤的分析表明，其损伤尺寸不符合这一相似规律。

NUMERICAL MODELING OF SCALE EFFECTS ON THE RESPONSES OF LAMINATED COMPOSITE PLATE UNDER LOW VELOCITY IMPACT

Based on scaling rules, three 3D finite element models were established for studying scale effects on the response of composite laminated plate under low-velocity impact. In the finite element model, Modified Chang-Chang criteria was used to predict interlaminar damage in a composite plate subjected by low-velocity impact, and delamination between the ply interfaces was simulated by interface elements. Material property should be degraded once impact damage generated. Three composite laminated plates of different size under low-velocity impact were analyzed with these three finite element models, and impact response under different impact velocity was compared. According to the results，some conclusions can be obtained: If the lower impact velocity did not generate damage in the composite laminated plates, the displacement and the contact force agree with the presented scaling rules; Whereas, the contact force does not agree with the scaling rules well once the impact damage was generated, moreover, if the velocity ratio between different models was equal to the square root of their scale factor, the relative delamination size in the models was nearly the same. These conclusions were agreed with experimental results. Further investigation on the in-plane damage shows that its size is not consistent with the scaling rule.