Study on fatigue life prediction method of composite laminates

复合材料层合板疲劳寿命预测方法研究

¹ School of Science, Chang'an University, Xi’an 710064, China
² School of Civil Engineering, Chang'an University, Xi’an 710064, China
³ School of Aeronautics, Northwestern Polytechnical University, Xi’an 710072, China
⁴ Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing 100190, China

Received: 24 September 2021

Abstract

Advanced composites have been widely used in aerospace field and transportation field in ground due to their excellent mechanical properties. Fatigue damage and life prediction of composites have always been the important and difficult issues in the field of composite mechanics. In this paper, the maximum stress criterion and Puck criterion were extended to fatigue failure criterion, and the fatigue damage analysis model of composite laminates was established by combining the gradual degradation model of material properties, the regularized fatigue life analysis method and the fatigue damage accumulation theory. Then, the model was used to predict the damage evolution and failure mechanism of composite laminates, and the fatigue tests with three stress levels (55%, 60% and 65%) were conducted. The fatigue life and failure mode of the numerical results matches well with the test results. Under fatigue loadings, the fatigue damage initiated from free edges on both sides of the plate to the inside of the laminates. The matrix damage first appeared in the 90° plies on two free sides, then the matrix damage and fiber damage of 45° plies were induced. The fiber damage of 0° ply finally appears and rapidly spreads to the center of laminates until the damage covers the entire cross section.

摘要

复合材料由于其优异的力学性能在航空航天和地面交通运输领域得到了广泛应用, 其疲劳损伤分析与寿命预测一直是复合材料力学研究领域的重点和难点。将最大应力准则和Puck准则扩展为疲劳失效准则, 结合材料性能逐渐退化模型、正则化疲劳寿命分析方法和疲劳损伤累积理论, 建立了复合材料层合板疲劳损伤分析模型。采用该模型预测了复合材料层合板疲劳损伤演化和失效过程, 并进行55%, 60%和65%三级应力水平下的疲劳试验, 模型预测的疲劳寿命及失效模式与试验结果吻合。疲劳加载下层合板疲劳损伤从两侧自由边向内侧发展, 90°铺层两自由边首先出现基体损伤, 随后诱发45°铺层的基体和纤维损伤, 0°铺层纤维损伤最后出现, 并迅速向中心扩展, 直至损伤覆盖整个横截面。