Analytical modeling of stiffness reduction in symmetric and balanced laminates due to cracks in 90° layers
Analytical modeling of stiffness reduction in symmetric and balanced laminates due to cracks in 90° layers
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DOI：
10.1016/s0266-3538(99)00025-1
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发表时间：
1999-01-01
影响因子：
9.1
通讯作者：
Varna, J
中科院分区：
文献类型：
--
作者：
Joffe, R;Varna, J
分析了 [S,90(n)](s) 对称层压板（包含正交各向异性子层压板 (S) 和破裂的 90 度层）的刚度降低。导出了将刚度变化与横向裂纹密度相关的封闭式表达式。它们仅包含材料属性、层压板几何形状和与归一化平均裂纹张开位移成比例的应力扰动函数。 [S,90(n)](s) 配置采用应力分布模型 [剪切滞后，基于变分法和有限元分析 (FEA)]，并用于计算应力扰动函数。将预测结果与 [+/- theta, 90(4)](s) theta = 0、15、30、40 玻璃纤维/环氧树脂层压板的实验数据进行比较。一般来说，FEA 模型会稍微低估刚度降低，而使用的两种变分模型都会产生类似的结果，略低于实验结果。如果首先从相同材料的交叉凸点层压板的拟合测试结果获得剪切滞后参数，则即使剪切滞后模型也可以成功使用。 (C) 1999 Elsevier Science Ltd. 保留所有权利。
Stiffness reduction in [S,90(n)](s) symmetric laminates, containing orthotropic sub-laminates (S) and cracked 90 degrees layer, is analyzed. Closed-form expressions relating stiffness changes to the transverse crack density are derived. They contain only material properties, laminate geometry and a stress-perturbation function that is proportional to the normalized average crack-opening displacement. Stress-distribution models [shear lag, based on variational approach, and finite-element analysis (FEA)] are adopted for the [S,90(n)](s) configurations and used to calculate the stress-perturbation function. Predictions are compared with experimental data for [+/- theta, 90(4)](s) theta = 0, 15, 30, 40 glass-fiber/epoxy-resin laminates. Generally the FEA model slightly underestimates stiffness reduction whereas both of the variational models used lead to similar results, slightly lower than experimental. Even the shear-lag model may be successfully used if the shear-lag parameter is first obtained from fitting test results for cross-pip laminate of the same material. (C) 1999 Elsevier Science Ltd. All rights reserved.