Study On Lap FSW Of Linear Induction Motor Secondary Conductor

Maglev rail transit is a new type of transportation that is green,safe and intelligent.The linear motor is used as the traction and braking system of the maglev rail transit system and is the core component of the maglev rail transit.The induction board is an indispensable part of the linear motor.The quality of the induction board of the linear motor plays an important role in the maglev rail transportation.The research on the processing method of the induction board of the linear induction motor is of great significance to the development of the maglev rail transportation.In this topic,the friction stir welding（Friction Stir Welding,FSW）technology of the lap method is used to replace the traditional explosive welding technology for the composite processing of the linear motor induction plate.The subject takes 2024-T3 high-strength aluminum alloy and Q235steel plate as the research object.Through the combination of experimental analysis,theoretical calculation and numerical simulation,the optimal process parameters of aluminum/steel dissimilar materials FSW lap are determined Joint forming,the influence of microstructure and mechanical properties,analysis of the internal relationship between Intermetallic Compound（IMC）and joint fracture behavior;and a new method combining metallographic structure analysis,three-dimensional reconstruction numerical simulation and experiment The mechanical/metallurgical bonding strength of the joint is obtained;the residual stress distribution of the plate is studied by means of numerical simulation.FSW lap experiment was conducted on 3mm-thick 2024-T3 high-strength aluminum alloy and Q235 sheet.The orthogonal test analysis method was used to determine the FSW process parameters of aluminum/steel dissimilar materials.The optimal process parameters are n=1000r/min and v=80mm/min.The mechanical properties of the joint are analyzed.The maximum tensile shear load of the mechanical properties of the joint is 4.28 kN.Using OM,SEM,XRD and other analytical testing methods to characterize the structure and interface characteristics of aluminum/steel lap joints,it was determined that FeAl and FeAl₃intermetallic compounds were produced during the FSW connection process of aluminum/steel dissimilar metals;the joint fractures were analyzed A river-like cleavage step was found,and FeAl,FeAl₃,Fe₃Al,and FeAl were detected from the aluminum and steel side fractures,respectively.It was confirmed that the fracture form of the aluminum/steel dissimilar metal FSW joint is brittle fracture and the cause of the crack is Formation of intermetallic compounds.For the aluminum/steel lap joints obtained by 3mm 2024-T3 high-strength aluminum alloy and5mm Q235 steel at n=1000 r/min,v=80mm/min,△h=0.3 mm,observe the aluminum/steel through a metallurgical microscope The microstructure and morphology of the joint area of the joint material.Take a length of joint to analyze the layered metallographic structure,obtain the metallographic picture of the joint,and use MATLAB software to three-dimensionally reconstruct the material mixing in the length of the joint to obtain the three-dimensional distribution of the joint material and the joint structure corresponding to the three-dimensional distribution of the joint material Perform numerical modeling to obtain the corresponding mechanical structure.Based on ANSYS static analysis calculation,perform numerical simulation on the obtained mechanical structure and calculate the mechanical structure strength to obtain the maximum tensile shear load of 1859.5N,comparing the maximum obtained by the static tensile test With a tensile shear load of 4.28kN,the contribution of the metallurgical bonding strength of the joint to the joint strength is 56.55%.For the friction stir lap welding of 3mm 2024-T3 high-strength aluminum alloy and Q235 steel,a numerical simulation method was used to simulate the temperature change during the FSW process,and the FSW heat source model with the rotation speed of the stirring head and the welding speed as variables was established and Based on this,the FSW temperature field numerical simulation of aluminum/steel dissimilar metals is carried out,and then the overall residual stress value of the welded plate is obtained,and the residual tensile stress is mainly concentrated at the center of the weld seam of the welded plate.Clamping force is provided within an appropriate range.The magnitude of the clamping force will offset the influence of part of the tensile stress.The outwardly spread tensile stress is cancelled by the clamping force,but the residual compressive stress on both sides of the weld will also increase.The speed can be increased by controlling the temperature,which will significantly increase the residual stress in the joint.