本文针对变刚度复合材料开孔板的失效行为展开研究，通过其主应力分布拟合了曲线纤维的铺放路径，并构建了一个同时考虑各向异性和准脆性的相场模型，用以预测变刚度复合材料损伤演化行为。首先，在统一相场模型的基础上引入方向相关的裂纹面密度函数以刻画裂纹扩展过程中的各向异性特征。然后，构建了适用于混合失效模式的相场驱动力和损伤本构关系，从而使模型具备分析混合失效机制的能力。通过在UEL子程序中实现交替求解格式和构建单元分层结构，使得相场模型可以通过ABAQUS进行数值计算。为了验证相场模型的准确性与适用性，本文分别对直纤维和曲纤维复合材料的单边带缺口板进行损伤失效分析，结果表明该模型能够合理预测复合材料力学行为和裂纹扩展路径。最后，基于该模型开展了常刚度与变刚度开孔板的拉伸失效模拟与损伤演化分析。结果显示：各向异性相场模型表现出良好的模拟复合材料损伤演化与断裂的能力；以主应力方向为纤维路径设计的变刚度开孔板相较于常刚度开孔板拉伸强度显著提升。

This study investigates the failure behavior of open-hole variable stiffness composite (VSC) laminates. A fiber placement path was fitted based on the distribution of principal stresses, and an anisotropic and quasi-brittle phase-field model was developed to predict the damage evolution in VSCs. First, a direction-dependent crack surface density function was introduced into the unified phase-field framework to capture the anisotropic characteristics during crack propagation. Then, a phase-field driving force and damage constitutive relationship suitable for mixed failure modes were constructed, enabling the model to analyze coupled fail-ure mechanisms. By implementing an alternate solution scheme and a layered element structure in the UEL subroutine, the phase-field model was numerically solved using ABAQUS. To verify the accuracy and applicability of the model, damage and failure analyses were conducted on single-edge-notched plates made of straight-fiber and curved-fiber composites, respectively. The results indicate that the model can reasonably predict the mechanical behavior and crack propagation paths of composite laminates. Finally, the model was used to simulate the tensile failure and damage evolution of open-hole plates with constant and variable stiffness. The results show that the predicted crack paths agree well with experimental observations, and the tensile strength of the variable stiffness plate is significantly improved compared to that of the constant stiffness plate.