碳纤维复合材料假脚冲击后疲劳性能影响因素分析

基于三维逐渐损伤理论和有限元法,对碳纤维复合材料假脚在冲击载荷及冲击后疲劳载荷作用下的破坏过程进行分析,研究了不同冲击能量、不同冲头材料、不同应力水平等因素对碳纤维假脚的冲击损伤及疲劳性能的影响规律。结果表明,在冲击载荷作用下,碳纤维复合材料假脚的损伤模式主要为基体开裂、纤维压缩和分层。随着冲击能量的增加,上述3种破坏模式的损伤单元数逐渐增大;尽管随着冲击能量的增加,碳纤维复合材料假脚的疲劳循环次数逐渐降低,但二者之间并不满足线性关系,即存在冲击能门槛值。对于碳纤维复合材料假脚而言,其冲击能门槛值为7J;冲头材料越硬,碳纤维复合材料结构件的冲击损伤面积越大,疲劳性能下降越剧烈;碳纤维复合材料假脚的疲劳循环次数随着加载应力的增加而显著降低。

Influencing Factors Analysis for Fatigue Property of Carbon Fiber Composites Prosthetic Foot after Impact

The damage process of carbon fiber composites prosthetic foot under the impact loading and fatigue loading after impact were analyzed based on the 3D progressive damage theory and finite element method. The influence of impact energy, impact tup material and stress level on the impact damage and fatigue property of prosthetic foot were researched. The results showed that the main damage modes of carbon fiber composites prosthetic foot under the impact loading were matrix cracking, fiber crushing and delamination. The damage area of these damage modes increased with the increasing impact energy. Although the fatigue life cycle gradually decreased with the increasing impact energy, there was no linear relationship between them, which meant that there was a impact energy threshold. For carbon fiber composites prosthetic foot, the threshold was 7 J. With the enhancement of the hardness of impact tup, the impact damage area increased and fatigue property decreased wildly. The fatigue life cycle of carbon fiber compo-sites prosthetic foot decreased rapidly with the increasing stress level.