Research CFRP-metal Transmission Shaft Connection And Hole Making Process

Multi-rotor aircraft is a new aircraft type in recent years,which featuring multi-function and flexible take-off and landing.Multi-rotor aircraft and has been widely used in military,agriculture and other fields.The oil-powered rotor craft has good development prospects because of its outstanding advantages of heavy load and long flight time.In order to increase the load capacity and enhance the mechanical property of the transmission system of oil-powered rotor craft,the carbon fiber reinforced polymer(CFRP)is used to make transmission shaft.The CFRP has been served as the optimum material for weight reduction and efficiency improvement in the field of aerospace because of the advantages of high specific strength,high specific rigidity and property designability.In order to improve the torsional strength of CFRP-metal transmission shaft,this paper studies from two aspects:improving the quality of hole making and optimizing the connection mode.The model of binary right-angle free cutting force was established and the main factors that caused delamination damage during drilling of CFRP were analyzed.The formula was derived under the condition that the drill had a positive rake angle and a fiber direction angle was0~0<θ<90~0.The results show that the magnitude of the axial force is determined by the carbon fiber material,the geometry of the drill bit and the processing parameters.The method of hole-making test is used to obtain the influence of drill geometry and processing parameters on delamination damage.In order to suppress the delamination damage of CFRP,based on the micro-bending behavior of carbon fiber in the process of drilling CFRP,the processing method of aluminum alloy bushing inside and outside the CFRP tube was proposed.The processing methods with or without bushings were compared and analyzed by combinating of finite element simulation and experimentations.The adjust delamination factor was used to quantitatively calculate the hole quality.The results show that the addition of the inside and outside aluminum alloy bushing of CFRP tubes can effectively reduce the delamination damage during drilling.The quality of the entrance and exit of holes was increased by 4.4%and 8.3%.Meanwhile,the torque of the transmission shaft is increased from 443N·m to 499N·m,which proves that the structural strength is affected by the quality of hole.In order to improve the torsional strength of the drive shaft based on CFRP-metal.In this paper,based on the torsion failure of the pin-connected CFRP-metal transmission shaft,a hybrid connection method with inside and outside bushings was proposed.The results show that the addition of the inside and outside aluminum alloy bushing of CFRP tubes can suppress the extrusion effect of the pins on the connecting holes is restrained.The torque values of the optimized transmission shaft is increased from 499N·m to 952N·m.