This study presents a novel method to describe the microscale phenomenon of cracks initiation based on sensitivity analysis in laminate fiber-reinforced composites. The failure of fiber-reinforced composite laminates often roots in the microscale phenomenon of fiber/matrix interfacial debonding. The micro-cracking and interfacial debonding in composites are difficult to detect both experimentally and numerically. This paper shows that the sensitivity of the stress response in a transverse ply with respect to individual fiber/matrix interface cohesive properties follows a normal distribution before cracks initiate. The distribution of the sensitivities rapidly deviates from a normal distribution from crack initiation to the formation. Several realistic microstructural representations of a fiber-reinforced composite laminate are simulated to validate the proposed method of detecting crack initiation. This proposed prediction method of crack initiation can be used as a failure risk indicator to increase the reliability of laminates’ designs.

本研究提出了一种基于敏感性分析的层压纤维增强复合材料中描述裂纹萌生微观现象的新方法。纤维增强复合材料层压板的失效通常源于纤维/基质界面剥离的微观现象。复合材料中的微裂纹和界面剥离很难通过实验和数值检测。本文表明，在横向层中，应力响应对单个纤维/基体界面粘结特性的敏感性遵循正态分布，然后才产生裂纹。敏感度的分布迅速偏离了从裂纹萌生到地层的正态分布。模拟了纤维增强复合材料层压板的几种实际的微观结构表示，以验证所提出的检测裂纹萌生的方法。提议的裂纹萌生预测方法可以用作失效风险指标，以提高层压板设计的可靠性。