自研高性能胶胶粘CFRP-钢界面性能的温度影响机制

Effect mechanism of temperature on the interface properties of CFRP-steel bonded by self-developed adhesive

粘结界面是碳纤维增强复合材料(CFRP)加固钢结构的薄弱环节,受胶粘剂和温度影响显著。为深入了解自研高性能胶胶粘CFRP-钢界面性能的温度影响机制,制作了28个CFRP-钢双搭接试件,开展了自研高性能胶粘剂G3和典型商品胶粘剂Sika30分别在7种环境温度下(-20℃、-5℃、10℃、25℃、40℃、55℃和70℃)的拉伸剪切试验。分析了试件的破坏模式、极限承载力、荷载-位移曲线、界面剪应力及粘结-滑移曲线等。结果表明:随温度升高,胶粘剂强度降低,韧性增加;当温度接近或超过胶粘剂玻璃转化温度,胶体性能急剧下降,搭接试件的破坏模式由CFRP层离破坏变为钢-胶界面破坏,界面性能显著降低;G3试件的低温性能与Sika30试件相当,但G3胶粘剂试件的高温性能显著优于Sika30胶粘剂试件;试件在低温环境下的界面性能较25℃显著降低,胶粘CFRP加固钢结构需考虑低温下加固系统脆化产生的不利影响。

Bonding interface is the weak link of carbon fiber reinforced polymer(CFRP)reinforced steel structure,which is significantly affected by adhesive and temperature.In order to investigate the effect of temperature on the interfacial properties of CFRP-steel bonded by a self-developed high-performance adhesive,28 CFRP-steel double lap specimens were prepared.The tensile shear tests of self-developed high-performance adhesive G3 and typical commercial adhesive Sika30 were carried out at 7 ambient temperatures(-20℃,-5℃,10℃,25℃,40℃,55℃and 70℃).The failure mode,ultimate bearing capacity,load-displacement curve,interface shear stress and bond-slip curve of the specimens were analyzed.The results show that the strength of the adhesive decreases and the toughness increases with the increase of temperature.When the temperature is close to or exceeds the glass transition temperature of the adhesive,the colloidal performance decreases sharply,and the failure mode of the lap joint specimen changes from CFRP layer separation failure to steel-adhesive interface failure,and the interface performance decreases significantly.The low temperature performance of G3 specimen is comparable to that of Sika30 specimen,but the high temperature performance of G3 adhesive specimen is significantly better than that of Sika30 adhesive specimen.The interface performance of the specimen at low temperature is significantly lower than that at 25℃.The adverse effects of brittleness of the reinforcement system at low temperature should be considered in the steel structure strengthened with adhesive CFRP.