A combined stress/energy-based (CSE) criterion is developed to predict mixed mode I/II fracture behavior in laminated composites by taking into account the effect of fiber bridging toughening. Following the proposed criterion, first, the absorbed energy resulting from fiber bridging micro-mechanisms is obtained and translated into a defined effective critical distance (i.e., the size of the crack tip micro-cracking zone). Then, the maximum principal stress is evaluated at the calculated effective critical distance around the crack tip to predict the onset of fracture. The CSE criterion is employed, along with other criteria, to predict experimental data reported in the literature on the onset of mixed mode I/II fracture in laminated composites and wood species (i.e. orthotropic composites). A higher correlation is found between the theoretical results predicted by the CSE criterion and the test data, as compared to other criteria. The stress-based formulation of the CSE criterion offers more computational simplicity as compared to the energy-based criteria while providing an acceptable accuracy and taking into account the effects of absorbed energy resulting from the micromechanical fiber bridging in the solution.

通过考虑纤维桥接增韧的影响，开发了基于应力/能量的组合（CSE）准则来预测层压复合材料中的混合模式I / II断裂行为。遵循提出的标准，首先，获得由纤维桥接微机制产生的吸收能量，并将其转换为定义的有效临界距离（即，裂纹尖端微裂纹区域的大小）。然后，在计算出的裂纹尖端周围的有效临界距离处评估最大主应力，以预测断裂的发生。CSE标准与其他标准一起用于预测文献中报道的层压复合材料和木材（即正交各向异性复合材料）混合模式I / II断裂的发生的实验数据。与其他标准相比，在CSE准则预测的理论结果与测试数据之间发现更高的相关性。与基于能量的准则相比，CSE准则的基于应力的公式提供了更多的计算简便性，同时提供了可接受的准确性，并考虑了由微机械纤维在溶液中桥接所产生的吸收能量的影响。