Fiber-reinforced polymer composites exhibit orthotropic mechanical properties and particularly low strength in the out-of-plane direction. The use of classical failure criteria that consider transverse isotropy to evaluate these composite materials implies an overestimation of their out-of-plane strength, which could lead to a nonconservative and even catastrophic design. The Molker failure criteria developed for orthotropic materials consider the LaRC05 failure modes as a basis, with two additional failure modes for the out-of-plane direction of noncrimp fiber (NCF)-reinforced composites. Given the similarity in configuration and orthotropic behavior of unidirectional fiber fabric reinforced composites to NCF-reinforced composites, Molker failure criteria are implemented and applied in this research to determine the initiation of out-of-plane failure in unidirectional fiberglass fabric composites. The criteria are programmed in the form of a module coupled to a constitutive model available in a finite element method (FEM) package. Then, the mechanical properties and failure parameters of the unidirectional fiber-reinforced composite are determined. Model validation is accomplished by comparing numerical and experimental results of out-of-plane failure in a corrugated panel. In addition, several failure criteria used in unidirectional fiber-reinforced composite that consider transverse isotropy are evaluated. The results of critical load at the onset of transverse out-of-plane failure obtained by using the Molkerorthotropic criterion prove to be superior in accuracy compared to those obtained with the criteria commonly applied to this type of materials.

中文翻译：

---

单向纤维增强复合材料失效的数值预测

纤维增强聚合物复合材料表现出正交各向异性的机械性能和特别低的面外方向强度。使用考虑横向各向同性的经典失效标准来评估这些复合材料意味着高估了它们的面外强度，这可能导致非保守甚至灾难性的设计。为正交各向异性材料开发的 Molker 失效标准以 LaRC05 失效模式为基础，另外还有两种针对非卷曲纤维 (NCF) 增强复合材料的平面外方向的失效模式。鉴于单向纤维织物增强复合材料与 NCF 增强复合材料的构型和正交各向异性行为相似，Molker 失效标准在本研究中实施和应用，以确定单向玻璃纤维织物复合材料中平面外失效的开始。标准以模块的形式编程，该模块耦合到有限元方法 (FEM) 包中可用的本构模型。然后，确定了单向纤维增强复合材料的力学性能和失效参数。模型验证是通过比较波纹板中平面外故障的数值和实验结果来完成的。此外，评估了考虑横向各向同性的单向纤维增强复合材料中使用的几个失效标准。