碳纤维增强树脂复合材料预紧力齿连接试验

Experimental study on the pre-tightened tooth connection of carbon fiber reinforced polymer

为探明桥梁用碳纤维增强树脂复合材料(CFRP)预紧力齿连接破坏模式和承载性能,以预紧力(23 MPa、34.6 MPa、53 MPa、64.5 MPa)、齿深(0.5 mm、1 mm、2 mm)、齿长(8 mm、16 mm、24 mm)和齿数(1道齿、3道齿和6道齿)为变化参数,进行了共计68个预紧力齿连接接头拉伸试验。根据荷载-位移曲线、应变及破坏模式的测试结果,分析了各参数变化对复合材料预紧力齿连接接头力学性能的影响。研究结果表明:CFRP预紧力齿连接接头存在4种破坏模式−剪切破坏、压溃破坏、纵向劈裂和纤维拉断;接头荷载-位移曲线有两种特征,荷载在达到极值后突然下降及荷载在达到极值后缓慢下降,前者接头发生剪切或纤维拉断破坏,后者接头发生压溃或劈裂破坏;预紧力多齿接头荷载分配不均匀,发生压溃破坏的接头比发生剪切破坏的接头内力分配更均匀,不管接头发生压溃破坏还是剪切破坏,第一道齿承担的载荷分配比最大,齿数越多,接头的最大载荷分配比越小,当预紧力超过53 MPa时,预紧力变化对接头破坏时第一道齿的影响不明显;当预紧力、齿深和齿长分别小于53 MPa、2 mm和16 mm时,接头连接强度分别随预紧力、齿深和齿长的增加而增加,当预紧力和齿长分别超过53 MPa和16 mm时,接头连接强度变化不大,在6齿范围内,接头连接强度随齿数的增加而增加。

To investigate the failure modes and load-bearing performance of pre-tightened tooth connections of carbon fiber reinforced polymer(CFRP)in the bridge engineering,a total of 68 tensile specimens were carried out with transverse pre-tightened force(23 MPa,34.6 MPa,53 MPa,64.5 MPa),tooth depth(0.5 mm,1 mm,2 mm),tooth length(8 mm,16 mm,24 mm)and tooth number(one tooth,three teeth and six teeth)as variable parameters.According to the test results of load displacement curve,strain and failure mode,the effects of various parameters on the mechanical properties of the joint were analyzed.The results show that there are four failure modes for CFRP pre-tightened tooth joints:Shear failure,crushing failure,longitudinal splitting failure and fiber breaking failure.There are two characteristics of the load-displacement curves of the joint:The load drops suddenly after reaching the extreme value and the load decreases slowly after reaching the extreme value.The former joints are subjected to shear failure or fiber breaking failure,while the latter joint is subjected to crushing failure or splitting failure.The load distribution ratio of pre-tightened multi-tooth joints is uneven,the load distribution ratio of the joint with crushing failure is more uniform than that of joint with shear failure.Whether the joint is crushing or shear failure,the load distribution ratio of the first tooth is the largest.The more the number of joint teeth,the smaller the maximum load distribution ratio of the joint.When the pre-tightened force,tooth depth and tooth length are less than 53 MPa,2 mm and 16 mm respectively,the joint strength increases with the increase of pre-tightened force,tooth depth and tooth length.When the pre-tightened force and tooth length exceed a certain value of 53 MPa and 16mm respectively,the joint connection strength changes little.In the range of 6 teeth,the joint strength increases with the increase of the number of teeth.