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为建立剩余刚度与材料损伤量及剩余寿命的关系,将纤维增强树脂复合材料(FRP)层合板在拉-拉疲劳载荷作用下的失效模式划分为纤维间破坏、纤维随机断裂与分层3种类型,分析不同失效模式与剩余刚度退化量的定量关系,提出一个集成各失效模式影响的剩余刚度退化复合模型。该模型适用于占寿命绝大多数比例的Ⅰ、Ⅱ阶段,避免了Ⅲ阶段刚度降不确定性的影响。剩余刚度退化曲线按时间尺度归一化,消除了试件个体分散性影响,分散性显著降低。对4种E-glass/Epoxy玻璃纤维复合材料层压板与3种AS-4/聚醚醚酮(PEEK)碳纤维复合材料层压板的疲劳试验结果进行了统计分析,表明本文模型适于精确描述复合材料的剩余刚度下降规律。
In order to establish the relationship between the residual stiffness and the amount of material damage and the remaining life, the failure modes of the FRP laminates under the tension-pull fatigue loading were divided into three kinds: the inter-fiber failure, the random fiber breakage and the delamination Type, the quantitative relationship between different failure modes and the residual stiffness degradation is analyzed, and a composite model of residual stiffness degradation integrated with each failure mode is proposed. The model is suitable for stage I and stage II, which account for most of the life span, and avoids the influence of the uncertainty of the stage III stiffness drop. The residual stiffness degradation curve is normalized on a time scale, eliminating the influence of individual dispersion of the test pieces and significantly reducing the dispersion. The fatigue test results of four kinds of E-glass / Epoxy fiberglass composite laminates and three kinds of AS-4 / PEEK carbon fiber composite laminates are statistically analyzed, which shows that the model is suitable for accurately describing the composite Remaining stiffness of the material decreases.