反复低速冲击下短纤维复合材料的试验研究

Study on Short Fiber Composites Subjected to Repeated Low Velocity Impact

利用 MTS矩形波加载 ,研究了短纤维复合材料在反复低速冲击下的力学行为、温度变化规律和断裂特征 ,并与正弦波常规疲劳进行了对比。得出 :反复低速冲击下 ,短纤维复合材料割线模量、滞后圈面积的变化规律与常规疲劳时相同 ,最大、最小循环应变 (绝对值 )则分别高于常规疲劳时的对应值 ;两种载荷下的材料开裂、破坏特征以及控制因素相同 ,但温度变化规律不同 ;相同循环数下 ,与常规疲劳相比 ,反复低速冲击时 ,短纤维复合材料吸收的能量大而以热的形式耗散的少 ,说明材料用于损伤的能量多 ,因此 ,与常规疲劳相比 ,反复低速冲击对短纤维复合材料的危害更大。

Mechanical behavior, thermal and fracture characteristics of short fiber composites under repeated low velocity impact are studied by means of Materials Test System to simulate rectangle wave loading. They are compared with the results of the test under sinusoidal wave normal fatigue loading. It is concluded that the varying tendencies of secant module and the area of hysteresis loops under repeated low velocity impact are similar to that under normal fatigue. Maximum and minimum cycle strains (absolute value) are respectively higher than that under normal fatigue. The characteristics and control factors of composites cracking and fracture are alike in two loading conditions. But, the varying tendencies of composites′ temperature are not the same. In comparison with normal fatigue, under repeated low velocity impact, the composites absorb more energy and dissipate less heat energy. So the energy consumed by the damage is much more. Therefore, the load of repeated low velocity impact is more dangerous for the composite material.