Instability Simulation Of Friction Stir Welded Components In Rail Vehicle Field

In recent years,with the rapid development of rail transportation,rail vehicles have begun to use aluminum alloy materials that are light in weight,corrosion-resistant,and have a good appearance.At the same time of material replacement,there are more and more quality problems in the traditional welding technology,so the friction stir welding(FSW),which has good welding quality and wide adaptability,is gradually promoted to the production and manufacturing of rail vehicles.The components after FSW are not easy to have welding defects,but its residual state and other factors will affect the stability of the component itself and its service process,and then affect the use of rail vehicles.Therefore,the research on the instability of components after FSW has important scientific significance and engineering application value.In this paper,in order to analyze the mechanism and influencing factors of component instability,Abaqus finite element analysis software is used to simulate the instability of components during welding and service based on thermo-elastoplastic method and stress equivalent method.The main contents include:(1)The residual state analysis of thin plate based on thermo-elastoplastic method.Establish a three-dimensional thin plate model,and simulate the FSW welding process of thin plate by the sequential thermal mechanical coupling method,then compare with the test results to verify the effectiveness of the numerical model,analyze the influence of release time and release mode on the residual state simulation results in detail,and gave suggestions.(2)The instability analysis of thin plate welding process based on stress equivalent method.Explore the basic principle of stress equivalent method,and use this method to analyze the instability of FSW welded thin plate and verify its accuracy.In addition,this part discuss the calculation cost,grid sensitivity and constraints of the model,and select the optimal simulation scheme.Analyze the influence of process parameters on the instability of thin plates after welding by controlling the peak value of equivalent stress and its action width.(3)The instability analysis of thin plate in service process based on the stress equivalent method.A new constitutive relation is introduced to analyze the influence of the new constitutive relation on the result of components service stability,because the change of material properties after welding.Discuss the influence of the assembly process on the stress and deformation state of the sheet after welding,and superpose it with the welding residual state.Finally,introduce the stress state of components before service by stress equivalent method,on this basis,simulate the stress instability in the process of component service,anddeeply analyze the influence of process and assembly operation on the stability of components in service.