CFRP Countersink Hole Size And Error Influence Of Fatigue Performance On The Connection Structure

The countersink bolt connection is one of the most common connection modes in aircraft structure of Carbon Fiber Reinforced Polymer/Plastic(CFRP).The composite bolt connecting member countersink hole is equivalent to a potential source of fatigue damage,but the domestic and foreign scholars have little research for effect of composite countersink hole size and error on the fatigue property of connection structure.Therefore,the load transfer process,the fatigue failure process,the damage generation and the evolution method of the composite head bolt connection structure were studied in this paper.The main contents are as follows:Based on the three-dimensional constitutive model of CFRP and the failure criterion of Hashin,a finite element model for fatigue simulation of composite head countersink bolt connection structure was established.The stress field distribution in the connection area was studied,and the load transfer behavior of CFRP head countersink bolt connection structure was revealed.Based on the static load and dynamic load test of composite head sinking bolt connection structure,in fatigue process the stress distribution of joints was analyzed through test and simulation.Besides,the cause of connection structure defect was found.The influence of countersink hole fillet size,countersink hole depth error,countersink hole slope error and countersink hole axis eccentric error,on head bolt fatigue performance of composite sink were studied.By prediction and analysis of fatigue life of composite material connection structure,the different countersink hole size and the error influence of connection structure fatigue performance were revealed.Based on the test and simulation analysis of the composite head bolt connection structure,the damage form and evolution process of the connected component were studied.The fatigues failure mechanism of composite material bolt connection structure was revealed.In this paper,the fatigue failure mechanisms of countersink hole joint was analyzed.The influence of different countersink hole on connection structure fatigue performance was studied.the change law of fatigue life is revealed.Those researches can be used in optimize the connection component countersink holes manufacturing process and the connection process.Besides,the reaches provide theoretical support for the countersink hole geometric error evaluation criteria.