Presented test results on transverse cracking in cross-ply laminates upon tension–tension cyclic loading show that the increase of crack density depends not only on the maximum transverse stress in the cycle but also on the local cyclic stress ratio in the analyzed layer. To include the effect of the in the model with statistical failure stress distribution for crack initiation (based on Weibull distribution) adapted for fatigue, an equivalent stress is introduced in a similar manner as the equivalent strain energy release rate has been used for delamination crack propagation. The equivalent stress in the layer is defined as a power function of the maximum stress and the stress ratio in the layer. It was found, testing laminates with two different fiber contents that higher the local stress ratio in 90-layer, higher the transverse cracking resistance. Transverse crack density simulation using the developed equivalent stress model has been validated against test results.

中文翻译：

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等效应力概念用于解释局部循环应力比对拉拉疲劳横向裂纹的影响


所提出的正交层合板在拉伸-拉伸循环载荷下横向开裂的测试结果表明，裂纹密度的增加不仅取决于循环中的最大横向应力，还取决于分析层中的局部循环应力比。为了在模型中包含适合疲劳的裂纹萌生统计失效应力分布（基于威布尔分布）的影响，以与用于分层裂纹扩展的等效应变能释放率类似的方式引入等效应力。层中的等效应力定义为层中最大应力和应力比的幂函数。测试两种不同纤维含量的层压板发现，90层的局部应力比越高，抗横向开裂性能越高。使用开发的等效应力模型进行横向裂纹密度模拟已根据测试结果进行了验证。