Research On Friction Stir Welding Technology Of Metro Sleeper Beam Based On Numerical Simulation

The pillow beam is an essential load-bearing component of the front end of the subway.Its production quality directly impacts the operational safety of the vehicle.As a friction stir welding structure,the control of welding deformation and residual stress is one of the key concerns in the process design and production.Due to the large size of the pillow beam and complex welding process,the use of traditional experimental methods to achieve process design and optimization for the control of welding deformation and residual stress,the period is long,the material and labor and other related costs are high.Therefore,numerical simulation methods for welding deformation and residual stress distribution law for scientific and quantitative prediction,and as a basis for targeted control or elimination of residual stress-strain,the production of rail vehicles such as the metro has a significant value.In this paper,based on the finite element numerical simulation method,a model of aluminum alloy subway sleeper beam as the object of study,set up different process parameters,welding sequence of the friction stir welding process test program,the control of its welding deformation and residual stresses to study.First,the establishment of the subway pillow beam local and overall structure of the finite element model,based on the establishment of the combined heat source model,the use of sequential thermal coupling method for the local pillow beam structure of the numerical simulation of the welding process to extract the local model of the plastic strain value of the stable welding interval;and then use the "local-overall" mapping method for full-size Pillow beam model for elastic-plastic calculations,the residual stress,deformation results of the subway pillow beam structure,and the simulation results and test results of comparative analysis,the results show that: the simulation results and test results are consistent with the trend of distribution,simulation and test compared to the maximum amount of error within 15 %,the maximum error value of deformation within 0.5 mm,to verify the heat source model and stir friction welding process simulation model and calculation method reliability.Based on the above,the design of different stir friction welding process parameters under the orthogonal test,the results of multiple non-linear regression analyses,the residual stress,deformation,and process parameters between the mathematical model,and the model for particle swarm optimization calculations,the optimal solution for stir friction welding parameters under certain conditions;design different welding sequence scheme,the use of life and death unit technology to obtain the residual stress,deformation under each scheme Deformation results,through a comparative analysis of the results of the pillow beam structure of the optimal welding sequence program of friction stir welding.The results show that the particle optimization algorithm can be used to obtain the optimal process parameters for friction stir welding under certain conditions.The higher the constraint value,the more significant the optimization effect;scheme V is the optimal scheme in the designed welding sequence scheme.The conclusions obtained in this paper are expected to provide theoretical reference and technical support for selecting friction stir welding process parameters and developing the welding sequence scheme for the subway sleeper beam.