Temperature Field Analysis Of Welded Structure Of High-speed Train And Its Influence On Adhesive Properties

With the development of lightweight and high-speed train,elastic bonding technology gradually replaces mechanical bonding technology.However,the coating,assembly,commissioning and subsequent operation and maintenance stages of the car body are all related to the change of the design structure of the car body,which requires the welding change of the car body.The welding high temperature generated by the welding modification may affect the bonding performance.Therefore,it is necessary to analyze the temperature field of the welding structure of high-speed train.With the development of computer simulation experiment platform,finite element simulation can simulate the welding temperature field very well.In this paper,the finite element analysis theory of welding thermal process is systematically discussed.Three typical welding joints(butt joint,lap joint,T-joint)are taken as the object.The simulation calculation of all welding changed structures of 6005a-t6 aluminum alloy,q345nqr2 weathering steel and 06cr19ni10 stainless steel is carried out by using the finite element software SYSWELD.The welding process of changing structures is online combined with the typical welding The comparison of temperature measurement test,metallographic test and thermal cycle curve verifies that the heat source model of each structure check is feasible.The adhesive strips were placed on the test pieces of the typical welding changed structure at the positions of 50 mm,100mm,150 mm and 200 mm away from the weld.The temperature of each adhesive strip position was measured by fluke thermal imager during the welding process of the typical welding changed structure.The results show that the temperature measured by the test of each adhesive strip position is in good agreement with the temperature simulated by simulation,and the codes were obtained The temperature change rule of the modified structure.Referring to the heat source model and temperature measurement test of the typical modified structure,the simulation calculation is carried out for the rest of the modified structure,and the temperature change of each adhesive strip position in the welding process of the rest of the modified structure is given.Through the analysis of the temperature field of the other welding structure,it is concluded that the method of multi-layer and multi pass welding can reduce the maximum temperature of the welding process 50 mm away from the weld.In this paper,infrared spectrum,XRD spectrum analysis and SEM observation were carried out on the stripping interface through the strip stripping test,and the performance of adhesive after welding was analyzed.The results showed that the adhesive performance of the strip at all positions of the test piece coated with white top coat was unqualified,while the adhesive performance of the strip at all positions of the test piece coated with red primer was qualified.The possible reason was that the surface of the white top coat was too smooth,It has an effect on the performance of the adhesive,not on the welding temperature.In this paper,the experiment and finite element simulation are combined to provide theoretical basis and experimental reference for the formulation of the modified elastic bonding repair scheme.It promotes the application of finite element analysis technology in welding temperature field analysis and engineering.