Process optimization–oriented deformation control of large aluminum alloy structures from high-speed EMU

Predicting and controlling the welding deformation of large aluminum alloy structures are crucial to ensure the accuracy during the manufacturing of high-speed electric multiple units (EMUs). On the basis of heat source calibration, the dual ellipsoid heat source model and simplified equation parameters were used for metal-inert gas (MIG) welding, and the simulation of residual stresses obtained from the three numerical simulation methods was compared with the experimental values, and it was determined that the thermoelastic-plasticity method was used as a method to establish a high-precision inherent strain database. Based on this database, the welding deformation of the entire sidewall (23 m, 44 welds) was predicted and compared with the experimental data, and the error of the two results was less than 1 mm, and the simulation model was able to reflect the actual situation. Meanwhile, on the basis of this model, the effects of welding sequence, spot fixing method, and number of clamps on welding deformation were investigated separately, and the results showed that the reasonable welding sequence reduced the maximum deformation by 30.90%; the appropriate spot fixing method reduced the maximum deformation by 12.56%; and the reduction of the number of clamps by 9% could get the same effect as the original scheme, and the reduction of the number of fixtures by 18% could still ensure that the overall deformation was basically unchanged. Thus, process optimization can effectively control welding deformation, providing insights for improving the welding quality of aluminum alloy-based high-speed EMU structures.