Abstract Mode II fracture energy, GIIC, is a critical parameter for determining the propagation of delamination in composite laminates. Its value can be affected by Through-Thickness Compression (TTC) stress acting on the crack tip and here this effect has been studied using IM7/8552 carbon/epoxy laminates with cut central plies. External TTC loads were applied through bi-axial testing. Unidirectional (UD) cut-ply specimens were used to determine the TTC enhancement factor, ηG, for GIIC. A similar enhancement effect was also found in Quasi-isotropic (QI) specimens with 2 extra cut central 0° plies inserted into the layup. The TTC enhancement factor was implemented in a Finite Element Analysis (FEA) framework using cohesive interface elements, showing that the determined ηG can be successfully used to model the effect of TTC on delamination.

中文翻译：

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模式 II 断裂能量的全厚度压缩 (TTC) 增强因子的实验确定

摘要 II 型断裂能 GIIC 是确定复合层压板分层传播的关键参数。它的值会受到作用在裂纹尖端的全厚度压缩 (TTC) 应力的影响，这里已经使用具有切割中心层的 IM7/8552 碳/环氧树脂层压板研究了这种影响。通过双轴测试施加外部 TTC 负载。单向 (UD) 切割层样本用于确定 GIIC 的 TTC 增强因子 ηG。在准各向同性 (QI) 样本中也发现了类似的增强效果，其中 2 个额外切割的中心 0° 层插入到叠层中。TTC 增强因子是在有限元分析 (FEA) 框架中使用粘性界面元素实现的，表明确定的 ηG 可成功用于模拟 TTC 对分层的影响。