三维机织复合材料的弯曲疲劳性能

Bending fatigue behavior of 3-D woven composites

在材料测试系统MTS上,采用三点弯曲加载方式对超厚三维正交机织复合材料(玻璃纤维/不饱和聚酯)分别进行静态及疲劳试验,对该材料的疲劳性能进行探索和预测。结果表明,材料的疲劳衰变主要分为3个阶段:产生小裂纹的初始阶段;损伤累积扩张阶段;材料刚度加速退化,疲劳破坏阶段。材料中纤维的体积含量不仅对其静态力学性能影响很大,对弯曲疲劳性能同样起到决定性作用。通过对弯曲疲劳加载后的剩余模量进行理论分析,验证了理论分析和实验数据之间的一致性,为实际预测复合材料剩余模量提供了依据。

The 3-point bending test was performed on Material Testing System （MTS） to investigate the quasistatic and fatigue behavior of ultra-thick 3-D orthogonal woven composites （glass/unsaturated resin）, which aimed to predict the fatigue property of this material. The results revealed that the fatigue degradation of the material includes three stages： micro-crack appearing at initial stage, a long process of crack propagation and fatigue failure of the material after suffering the extraordinary degradation of stiffness. In addition, the fiber volume fractions of composites have great impact on the quasi-static mechanical property and play a decisive role in the fatigue behavior. Comparisons made between experimental data and a theoretical fatigue model show good agreement, which can be used to predict the fatigue residual modulus of composites.