CFRP板-钢黏结界面的疲劳性能

Fatigue Behavior of Bonding Interface between CFRP Laminates and Steel

开展了碳纤维增强聚合物(CFRP)板-钢双搭接试件的疲劳试验,考虑荷载水平的影响,分析了黏结界面的疲劳性能,比较了基于平均黏结应力幅或局部黏结应力幅的中值及设计疲劳曲线(S-N曲线)的适用性.结果表明:疲劳荷载下CFRP板-钢接头的主要破坏模式为钢-胶层界面剥离或钢-胶层/CFRP板-胶层界面剥离的混合破坏模式;不同荷载水平下荷载-位移曲线斜率的变化趋势大致相同;界面损伤从界面黏结应力较大的加载端开始,逐渐向自由端扩展,扩展至一定程度后界面突然断裂;采用幂函数公式预测试件的疲劳寿命时,基于平均黏结应力幅S-N曲线的拟合优越性更为显著,疲劳极限为1.88 MPa;最后,给出了具有95%可靠度的设计S-N曲线.

The fatigue experiments of carbon fiber reinforced polymer(CFRP)laminates-steel double lap joint specimens were carried out.Considering the effects of load levels,the fatigue behaviors of the interface were analyzed.Meantime,the applicability of the mean stress-number of cycle(S-N)curve and designed S-N curve based on mean or local bond stress range were compared.The results show that the main failure modes of specimens under fatigue load are steel-adhesive interface debonding or the mixed mode of steel-adhesive and CFRP laminate-adhesive interface debonding.The slope variation trend of load-displacement curves at different load levels is roughly the same.The interface damage starts from the load end with larger interfacial bond stress and gradually extends to the free end.After expanding to a certain extent,the interface suddenly fails.Using a power function formula to predict fatigue life of specimen,the fitting superiority of S-N curve based on mean bond stress range is more significant,and the fatigue limit is 1.88 MPa.Finally,the designed S-N curve with 95%probability is given.