Study On Laser Stir Welding Technology Of Carbon Fiber Reinforced Thermal Polymers And Aluminum Alloy

The composite structure of carbon fiber reinforced thermal polymers(CFRTP)and aluminum alloy is an effective structure that achieves lightweight manufacturing of aircraft and has reliable strength.In recent years,with the increasing application of laser processing technology,laser welding technology has become a popular method to achieve CFRTP-aluminum alloy hybrid structure join.However,when traditional laser welding is used to weld aluminum alloy,it is easy to cause some thermal damage such as pores and micro cracks,which becomes a potential threat to the failure of CFRTP/aluminum alloy joints.In order to reduce the thermal damage of the aluminum alloy surface and improve the joint strength,this article innovatively used laser stir welding technology to join the CFRTP-aluminum alloy composite structure.And the influence of micro-textured assisted join on the joint strength was studied.First,the finite element model of CFRTP/aluminum alloy laser stir welding was established,and the temperature field of the aluminum alloy weld seam was analyzed.It was found that the temperature field on the surface of the aluminum alloy changed smoothly in the form of non-constant oscillation,changing the temperature field of traditional laser heating.This is one of the reasons why laser stir welding can reduce the thermal damage of aluminum alloy.The comparison between the simulation and the experimental results showed that the weld depth and weld width errors are within 9.87%,and the change trend was consistent.Through the research on the temperature field of the join interface,it was found that the melting depth of the interface resin was consistent with the change trend of the joint strength from the actual test,which proved that the model can predict the joint strength.Secondly,the experimental study of CFRTP/aluminum alloy was carried out using laser stir technology.Compared with traditional laser linear welding,under the condition of the same heat input,the thermal damage of the aluminum alloy surface has been significantly improved by laser stir welding,and the joint strength is 3.25 times that of conventional laser linear welding.The single-factor method was used to study the influence laser stir welding of joint strength.Finally,the effect of interface micro-texture assisted join on the strength of CFRTP/aluminum alloy heterostructure joints was studied,and the effects of different micro-texture morphology,dimensions and thicknesses of added PA material on the strength of CFRTP/aluminum alloy joints were discussed respectively.Compared with the strength of the joint without any surface treatment,the joint with the micro-texture assisted join method of the interface is slightly improved by 260%.When the scanning pitch of the cross micro-texture is 0.1 mm and the thickness of the added PA material is 80 ?m,the laser power is 200 W,the welding speed is 5 mm/s,the stirring amplitude is 0.8 mm,and the stirring frequency is 40 Hz.Under this welding process parameters,the highest joint strength of 37.5 MPa was obtained.