循环变形提高SiC纤维增强铝基复合材料强度及塑性 Ⅱ.理论分析

CYCLE LOADING INCREASING THE STRENGTH AND PLASTICITY OF SiC FIBER REINFORCED ALUMINUM COMPOSITES II. Theoretical Analysis

采用断裂力学方法获得了纤维增强复合材料强度与脱粘长度、纤维临界长度以及纤维体积分数的定量关系 该公式较好地预测了纤维的临界长度以及强度与纤维体积分数的关系．并再现了复合材料混合定则．该公式也较好地解释了丝状复合材料强度随短期循环变形载荷与周次增加而增加的现象．其原因是在循环变形中、纤维与基体界面结合强度发生变化．导致纤维临界长度与脱粘长度发生变化、从血使复合材料强度增加、但这种增加是有限的和有范围的，循环变形的发展最终导致强度下降．

A relationship between strength and debonding length, fiber critical length and volume fraction of SiC fiber reinforced composite was obtained by fracture mechanics analysis, which can predict well the critical length, strength and fiber volume fraction, and reappears the Mixture Law in composites. The relationship explains well the experimental phenomenon, the strength and plasticity of fiber reinforced aluminum composites increases as fatigue cycles increase. The reason is that the interfacial adhesion strength was changed during fatigue, resulting in the critical and debonding lengths changed and the strength of composites increased. However, this strength increase is limited and finally, the strength will decrease with fatigue cycles increasing further as normal materials.