FRP复合材料剩余刚度退化复合模型

Compound model of residual stiffness degradation for FRP composites

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 residual stiffness,material damage quantity and residual life,failure modes of fiber-reinforced polymer（FRP）laminates under tension-tension fatigue load effect are divided into three types：inter fiber fracture,fiber random fracture and delamination.Based on the analysis of quantitative relationship between different failure modes and residual stiffness degradation quantity,a compound model of residual stiffness degradation,integrated each failure mode＇s influence,was put forward.This model is applicable to stageⅠ and Ⅱ,which occupy most of the life,avoids the influence of stiffness reduction uncertainty in stageⅢ.Normalization of residual stiffness degradation curve by time scale,eliminates individual specimens＇ dispersion effect,significantly reduces the dispersion.Statistical analysis was conducted for fatigue test results of four kinds of E-glass/Epoxy glass fiber composite laminates and three kinds of AS-4/polyether-ether-ketone（PEEK）carbon fiber composite laminates,which shows that the proposed model is suitable for an accurate description of the residual stiffness decline law of composites.