Numerical Simulation Research On Single-sided And Double-sided Arc Welding Of Aluminum Alloy Traction Beam

Aluminum alloy traction beam was mainly welded by aluminum alloy thick plates. Currently it was welded by single-sided MIG welding process and the efficiency was relatively low. Because of the symmetric heat resource and high efficiency of double-sided MIG welding process, the double-sided MIG welding process was studied in this paper. According to the key butt joint and T joint weld of aluminum alloy traction beam, the numerical simulation with finite element analysis software ANSYS on the single-sided MIG multi-pass welding process and the double-sided MIG multi-pass welding process was conducted in this paper. Through simulating the welding temperature and stress field of aluminum alloy thick plates, analyzing the temperature and stress distribution laws as well as comparing the temperature and stress distribution difference of different welding processes, the simulation support was provided for the companies to employ the advanced welding process of aluminum alloy traction beam.The thermal and mechanical finite element models of aluminum alloy thick plates were created. The double ellipsoid heat source model was chosen. The birth and death method was used. The welding temperature and stress fields on the single-sided MIG multi-pass welding process and the double-sided MIG multi-pass welding process were simulated. Its temperature and stress distribution laws were studied. On the one hand, the temperature distribution of different time points of the two joints on the single-sided MIG process and the double-sided MIG process was compared and analyzed in this paper, on the other hand, some sample dots’ heat recycle curves were compared and analyzed and these sample dots separately located along the center line of the weld and located on the vertical center line of the weld. It was revealed that, the temperature was highest in the center of weld pool and as the distance from the center of weld pool was longer, the temperature was lower; the isotherm of weld pool’s front was more concentrated than the isotherm of weld pool’s end, and also the temperature gradient was bigger; in the certain range of time, the peak temperature was almost constant and the welding stayed at quasi-state stage; the peak temperature of arc suppression was higher than that of quasi-state stage; the area with big temperature change of double-sided MIG process was bigger than that of single-sided MIG process; the high temperature zone of double-sided MIG process located at two sides of the joints, but the high temperature zone of single-sided MIG process only located at one side of the joints.The equivalent residual stress fields of two joints on the single-sided MIG process and the double-sided MIG process were compared and analyzed in the paper. The weld center line paths were chosen and the longitudinal stress curves of the single-sided MIG process and the double-sided MIG process were compared. It was revealed that: the equivalent residual stress was mainly concentrated in the weld zone and heat affected zone, exactly the equivalent residual stress near to starting arc and stopping arc was relatively big and residual stress away from the weld zone was relatively small; on the whole, the equivalent residual stress in the weld zone presented the trend that big in the middle but small at both ends; the peak residual stress of double-sided MIG process was lower than that of single-sided MIG process, furthermore, the concentrated residual stress zone of double-sided MIG process was smaller than that of single-sided MIG process. The longitudinal stress along the weld center line paths was tensile stress and presented the trend that big in the middle but small at both ends; the peak longitudinal stress at the firstly welded side of single-sided MIG process was lower than that at the secondly welded side; the longitudinal stress distribution at two sides of double-sided MIG process was almost same and the peak longitudinal stress of double-sided MIG process was lower than that of single-sided MIG process.It was revealed that: in terms of the residual stress distribution of aluminum alloy thick plates’ butt joint and T joint, compared with the single-sided MIG process, the double-sided MIG process could not only make the residual stress distribution of the weldments’ two sides to be symmetric, but also reduce the residual stress’ s peak value of the weldments on the whole. In a word, the double-sided MIG process had obvious advantages in some ways of improving the residual stress distribution and controlling the welding deformation.