胶膜连接碳纤维增强树脂复合材料板-钢搭接接头室温条件的力学性能试验

针对碳纤维增强树脂（CFRP）复合材料板-钢搭接接头连接的糊状胶黏剂粘层厚一致性控制较难、铅垂向成形可能不易等问题，将糊状胶黏剂换成胶膜，制作了胶膜连接的五种粘结长度共15个CFRP板-钢双搭接接头试件，并对该胶膜连接的CFRP板-钢搭接接头进行了室温条件下的破环模式、有效粘结长度、传力规律、粘结-滑移本构、承载力等的试验研究。结果表明:所用胶膜的连接强度略高于CFRP板层间强度（即碳纤维与树脂基体的黏聚强度）；室温下，所用胶膜连接的CFRP板-钢搭接接头有效粘结长度约为80 mm；加载初期，剪应力最大值位于接头钢板端；继续加载，其位置向接头CFRP板端移动；加载末期，其位置位于距接头钢板端20 mm （粘结长度不超过80 mm时）或者50 mm （粘结长度不小于120 mm时）处；胶膜连接的CFRP板-钢搭接接头界面粘结-滑移模型为近似梯形，不同于胶黏剂连接的CFRP板-钢搭接接头的近似三角形，胶膜连接接头的延性大为提升；所用胶膜连接接头界面峰值剪应力、断裂能、界面刚度等代表值（可视为准平均值）分别为四种典型商品胶黏剂连接接头的1.2~3.0倍、1.6~5.7倍和5.4~7.5倍；在粘结长度不小于有效粘结长度条件下，所用胶膜连接接头的抗拉承载力代表值为四种典型商品胶黏剂连接接头的1.25~2.39倍；胶膜连接接头的抗拉承载力、最大位移的变异系数与糊状胶黏剂连接接头相差不大。 

Experimental study on carbon fiber reinforced polymer laminate-steel lap joints connected with film adhesive at room temperature

In order to alleviate the difficulty in thickness control and forming for paste adhesive layer in fabrication of carbon fiber reinforced polymer(CFRP) laminate-steel lap joints, a type of film adhesive was used to replace traditional paste adhesives. A total of 15 CFRP laminate-steel double lap joints connected with a film adhesive, with five kinds of bond lengths, were fabricated, and experimental studies were conducted focused on the failure modes, effective bond length, force transfer law, bond-slip constitutive and bearing capacity at room temperature. The results show that the bond strength of the film adhesive used is slightly higher than the interlaminar strength of the CFRP laminates(i.e. the bond strength between carbon fibers and resin matrix). The effective bond length of the film adhesive-connected CFRP laminate-steel joints at the room temperature is approximately 80 mm. At the beginning of loading, the maximum shear stress is located at the end of the joint steel plate. Its position moves towards the end of the joint CFRP laminate with the increase of load. At the end of loading, its position is located at 20 mm(when the bond length is less than 80 mm) or 50 mm(when the bond length is greater than 120 mm) from the end of the joint steel plate. The bond-slip relationship of film adhesive-connected CFRP laminate-steel lap joints can be simplified as a trapezoid model which is significantly different from the triangle model of paste adhesive-connected joints, suggesting that the ductility of the film adhesive-connected joints has been greatly improved. The representative values(quasi mean values) of peak shear stress, fracture energy and interfacial stiffness of the film adhesive-connected joints are 1.2-3.0 times, 1.6-5.7 times and 5.4-7.5 times, respectively, of those of joints with four typical paste adhesives. When the bond length is not less than the effective bond length, the representative value of tensile capacity of the film adhesive-connected joints are 1.25-2.39 times of the joints connected with paste adhesives. The variation coefficients of tensile strength and maximum displacement of the film adhesive-connected joins almost have no difference from the joints connected with paste adhesives.