【摘要】 带衬套沉头螺栓连接已经在复合材料连接结构中得到了一定的应用,需要对其疲劳性能进行研究。本研究对一种单搭接3钉带衬套碳纤维复合材料/钛合金沉头螺栓连接接头进行了静态拉伸试验,测量了接头的载荷-位移曲线、拉伸极限强度与条件挤压强度。在此基础上,确定67%接头极限载荷为拉伸疲劳最大载荷,按应力比为0.1的循环载荷对接头进行疲劳试验,并与对应的无衬套接头进行了对比,研究了衬套对该接头疲劳性能的影响。结果表明,衬套的引入改善了应力分布情况,使结构疲劳寿命延长了98.4%。同时,静态拉伸试验中发生层合板的钉孔挤压以及净截面拉伸破坏,疲劳试验中发生钛合金板的拉伸疲劳破坏,部分无衬套接头还发生了螺栓疲劳破坏。经分析发现,两类材料的疲劳性能表现差异较大,复合材料/金属机械连接接头的疲劳破坏模式会因载荷水平的不同而发生变化,在低于一定载荷水平下容易出现金属结构的破坏。更多还原

【Abstract】 Countersunk bolt joints with sleeves have been used in composite connection structures, and the fatigue properties need to be studied. In thisstudy,a static tensile test is carried out on a single lap CFRP/titanium alloy bolted joint with 3-countersunk head bolt and sleeves, and thel oad-displacement curves, ultimate tensile strength and off-set bearing strength of the joint are measured. On this basis, 67% of the joint’s ultimate load is determined as the maximum tensile fatigue load. The joint is tested with a stress ratio of 0.1 and compared with the joint without sleeves to investigate the sleeves’ influence on the joint’s fatigue performance. The results show that the use of the sleeves improves the stress distribution and increases the fatigue life of the structure by 98.4%. At the same time, hole bearing and net section tensile failure of the laminate occurred in the static tensile test. In the fatigue test, tensile fatigue failure of the titanium alloy plate occurred, and bolt fatigue fracture also occurred in some joints without sleeves. It is found that the fatigue failure mode of the composite/metal mechanical joint varies with the load level due to the large differences in the fatigue performance of the two types of materials, and the metal structure is prone to damage when the load is lower a certain level.更多还原