高温对基于研发胶黏剂的CFRP板-钢板搭接界面力学性能的影响

Effect of high temperature on mechanical properties of CFRP plate-steel plate lapping interface based on developed adhesive

针对夏季钢桥面温度高达60℃左右,而温度对碳纤维增强复合材料(CFRP)加固钢结构黏结界面力学性能影响显著的现象。基于研制的高性能胶黏剂GY34,制作了21个胶黏剂拉伸试件、15个CFRP板-钢板双搭接试件,进行了不同温度下的准静态拉伸试验、剪切拉伸试验,揭示了高温(≤90℃)对胶黏剂力学性能及CFRP板-钢板搭接界面力学性能的影响规律,建立了考虑温度影响的搭接界面极限承载力预测模型,得到了黏结-滑移关系模型随温度的变化趋势。研究结果表明:随温度的升高,胶黏剂GY34拉伸强度及弹性模量逐渐降低;断裂伸长率及应变能先增大后减小,在温度接近胶黏剂的玻璃化转变温度Tg,S时达到峰值。随温度升高,基于研制胶黏剂的CFRP-钢搭接试件的极限承载力先增大后减小,破坏模式由CFRP板层离逐渐过渡为钢-胶层界面破坏。小于胶黏剂玻璃化转变温度Tg,S的高温下,荷载-位移曲线具有明显的延性发展阶段。随温度升高搭接试件的应变分布更加均匀,剪应力传递范围及有效黏结长度显著增加。基于研制胶黏剂的搭接试件的黏结-滑移关系的形状在不同温度下均为三线性梯形。高温环境不会改变黏结-滑移关系模型的形状,会导致界面剪应力峰值及刚度逐渐降低,相对滑移与界面断裂能先增加后减小。

According to the phenomenon that the temperature of the steel bridge deck reached about 60℃in summer,and significantly affect the mechanical properties of the bonding interface of carbon fiber reinforced composite(CFRP)-reinforced steel structure,a total of 21 adhesive tensile test pieces and 15 CFRP plate-steel double-lap joints were fabricated,and quasi-static tensile tests and shear tests at different ambient temperatures were performed,based on developed high-performance adhesive GY34.The influence of high temperature(≤90℃)on the mechanical properties of adhesive and the mechanical properties of bonded CFRP plate-steel lap joints was obtained.A prediction model for the bearing capacity of the lap joint interface considering the effect of temperature was established,and the trend of the bond-slip relationship model with the increasing of the temperature was obtained.The results show that the tensile strength and elastic modulus of the adhesive GY34 gradually decreases,and the elongation at break and the strain energy first increase and then decrease with the increasing of temperature,and reaching a peak when the temperature is close to the glass transition temperature Tg,S of the adhesive.With the increase of temperature,the bearing capacity of CFRP-steel lap joints based on the developed adhesive first increases and then decreases,and the failure mode gradually transits from CFRP plate delamination to steel adhesive interface failure.The load-displacement curve has a significant ductile development stage at high temperature below the Tg,S of the adhesive.With the increase of temperature,the strain distribution of lap joints becomes more uniform,and the shear stress transfer range and the effective bonding length increase significantly.The shapes of bond-slip relationship model of lap joints based on the developed adhesives are trilinear trapezoids at different temperatures.The shape of the bond-slip relationship model remains constant at high temperature,but the maximum shear stress and stiffness gradually decrease,and the relative slip and interface fracture energy first increase and then decrease with the increasing of temperature.