A detailed micromechanical finite element analysis methodology is presented to predict the transverse tensile (fiber perpendicular) failure behavior of a unidirectional (UD) glass fiber-reinforced plastic composite ply. In order to understand the constituent-level stress–strain and damage behavior, finite element analysis is accomplished using representative volume element (RVE) that consists of random fiber distribution as observed in the microscopic image of an actual composite ply. For modeling the fiber/matrix interface failure behavior, cohesive zone module (cohesive surface/cohesive element) of Abaqus® is used. In order to capture the epoxy matrix stiffness and strength degradation, the following two different approaches are used: (i) initially, the linear Drucker–Prager plasticity model in combination with a ductile fracture criterion is used; (ii) later, a brittle failure approach such as the quadratic normal stress criterion within the framework of eXtended finite element method is used. From the detailed micromechanical analysis of the RVE, it is observed that the initial damage in the RVE occurs in the form of fiber/matrix interface decohesion. With increasing tensile load, interface crack propagates and creates a stress concentration region in the matrix material, adjacent to the crack tip. Further load application causes both interface crack tip and matrix stress concentration to move away from the load application direction. As soon as the interface crack tip reaches approximately 60° to 70° away from the load application direction, the conjunction of the matrix damage with the interface crack leads to the RVE final failure. The predicted average stress–strain curves from the above-mentioned two different epoxy matrix failure criterions (ductile and brittle) correlate very well with the experimental results, indicating that the brittle failure behavior of a UD fiber-reinforced plastic composite ply under transverse tensile load is mainly controlled by the fiber/matrix interface properties.

中文翻译：

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单向玻璃纤维增​​强塑料复合材料层中横向拉伸损伤行为的计算微观力学模型：韧性与脆性断裂力学方法

提出了一种详细的微机械有限元分析方法来预测单向 (UD) 玻璃纤维增​​强塑料复合层的横向拉伸（纤维垂直）破坏行为。为了了解成分级应力应变和损伤行为，使用代表性体积元 (RVE) 完成有限元分析，该体积元由在实际复合层的显微图像中观察到的随机纤维分布组成。为了模拟纤维/基质界面失效行为，使用了 Abaqus® 的内聚区模块（内聚表面/内聚元素）。为了捕捉环氧树脂基体的刚度和强度退化，使用了以下两种不同的方法：(i) 最初，使用线性 Drucker-Prager 塑性模型与韧性断裂准则相结合；(ii) 稍后，在扩展有限元方法的框架内使用脆性破坏方法，例如二次法向应力准则。从 RVE 的详细微观力学分析可以看出，RVE 中的初始损伤以纤维/基质界面脱聚的形式发生。随着拉伸载荷的增加，界面裂纹扩展并在邻近裂纹尖端的基体材料中产生应力集中区域。进一步施加载荷会导致界面裂纹尖端和基体应力集中远离载荷施加方向。一旦界面裂纹尖端与载荷施加方向的距离达到大约 60° 到 70°，基体损伤与界面裂纹的结合导致 RVE 最终失效。上述两种不同环氧树脂基体破坏准则（韧性和脆性）的预测平均应力-应变曲线与实验结果非常吻合，表明 UD 纤维增强塑料复合材料层板在横向拉伸载荷下的脆性破坏行为主要由纤维/基质界面特性控制。