Abstract Delamination is one of the main mechanisms involved in the fatigue damage evolution in multidirectional laminates made of unidirectional plies. Typically, delamination is induced by off-axis cracks, the tips of which terminate at the interface with the adjacent layers. One of the consequences of the presence of delamination is the degradation of the apparent laminate stiffness. In this work, an analytical model is proposed for predicting the entire stiffness matrix of a generic symmetric laminate with off-axis cracks in one ply (and its symmetric) and a delamination originated from their tips. The model is based on an optimal shear lag analysis of the laminate and estimates the laminate elastic properties as a function of the crack density and the delamination length. The only input data required are the ply elastic properties, the ply thickness and the lay-up. The model is successfully validated against experimental data and Finite Element analyses.

中文翻译：

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具有离轴裂纹和分层的对称层压板的刚度退化：分析模型

摘要 分层是单向层板制成的多向层压板疲劳损伤演变的主要机制之一。通常，分层是由离轴裂纹引起的，其尖端终止于与相邻层的界面。分层存在的后果之一是表观层压板刚度的降低。在这项工作中，提出了一种分析模型，用于预测在一层（及其对称）中具有离轴裂纹和源自其尖端的分层的通用对称层压板的整个刚度矩阵。该模型基于层压板的最佳剪切滞后分析，并根据裂纹密度和分层长度估计层压板的弹性特性。唯一需要的输入数据是层弹性属性，层厚和铺层。该模型已通过实验数据和有限元分析成功验证。