形状记忆合金补强损伤钢板疲劳性能研究

钢结构在长期服役过程中,受荷载和环境作用,可能发生结构损伤及性能退化。形状记忆合金（shape memory alloy,SMA）因其特殊的形状记忆效应,可以为钢结构施加预应力,提升结构疲劳性能。以形状记忆合金补强的含损伤钢板为分析对象,采用线弹性断裂力学对补强后产生的钢板疲劳性能进行理论分析。与已有研究中的试验结果相比,钢板的疲劳寿命与试验结果最大相差不超过10%。同时,采用理论模型展开参数分析,研究初始损伤程度和SMA受温度作用产生的恢复应力对补强体系的影响。结果表明：对于不同的初始损伤程度,SMA均能够发挥很好的补强作用;经SMA补强后,钢板的疲劳寿命最大可提高362%;当SMA产生的恢复应力大于200 MPa时,可降低加载时钢板实际承担的应力幅,延缓裂纹扩展。

Theoretical analysis on fatigue behavior of cracked steel plates retrofitted with shape memory alloy

The aged steel structures generally deteriorate due to the service loads and environmental attacks. Attributed to the remarkable shape memory effect activated by heating and cooling, the shape memory alloy (SMA) can be conveniently used to induce prestress in steel structures and improve fatigue behavior of steel structures. A theoretical analysis on the fatigue behavior of cracked steel plates retrofitted with SMA was presented based on linear elastic fracture mechanics. In comparison with the experimental data from literature, the prediction shows reasonable results with a maximum deviation less than 10%. Afterward, a parametric study was performed to further investigate the effects of the initial damage degree and recovery stress of SMA on the fatigue behavior of strengthened steel plates. The results show that regardless of damage degrees, SMA presents remarkable performance in structural strengthening. The application of SMA successfully prolongs the fatigue life up to 362%. A recovery stress of SMA over 200 MPa is suggested, for which it can help to reduce the effective stress range and consequently retard the crack propagation.