# A MIG Welding Clamping Scheme for Power Battery Enclosure's Deformation Restrain
## 1 Introduction  
To face with the problems of environmental pollution and energy shortage, the world's major automobile industry countries have taken the new energy automobile industry as a core strategy in strategic choice. As the core component of a new energy vehicle, the power battery system mainly consists of power battery cooling module, battery management module, and power battery enclosure. The power battery enclosure is specially designed for accommodating more batteries to increase the cruising range, so its structure size is large. To fulfill the requirement of lightweight design, it is usually made of aluminum alloy. In its welding manufacture process, due to the large thermal expansion coefficient, good thermal conductivity and fast heat dissipation rate of the aluminum alloy, the long fillet weld between the enclosure bottom plate and the frame is prone to large welding deformation during MIG welding. Excessive welding deformation will have a great impact on the welding between the lifting lug and the side of the frame. In serious cases, it would lead to failure of welding. In terms of the numerical simulation of welding, [PERSON] et al. [1] proposed a method to analyze the thermal stress and residual stress in the welding process based on the finite element method and the thermal elastoplastic model, which makes it possible toquantify the stress and deformation in the welding process. [PERSON] et al. [2] proposed an intrinsic strain method to improve computing efficiency of the thermoelastic-plastic finite element method for large components and complex structures. [PERSON] et al. [3] proposed a shrinkage volume method for large and complex structural welded members, which can quickly predict the welding deformation by linear elastic finite element method. [PERSON] [4] adopted the finite element method to simulate the laser welding process of aluminum alloy sheets and predict the welding deformation. [PERSON] et al. [5] used ABAQUS software to simulate the welding thermal process of two butted stainless-steel plates. The results showed that the largest deformation after welding appeared in the weld area, which was in good agreement with the actual measured welding deformation. Based on theory of thermoelastic finite element, [PERSON] et al. [6] established a series of key techniques for the accuracy and computational efficiency of the numerical simulation of the welding stress-strain field. [PERSON] et al. [7] applied numerical simulation technique to simulate and predict the welding deformation of the aluminum alloy car body sheet manufactured by MIG welding. Compared with the measured deformation results, the error was within 20%. [PERSON] et al. [8] proposed a thermo-elastic-plastic finite element calculation method to simulate multi-layer multi-pass welding. The stress-strain fields of butt joints with various grooves were simulated. Accuracy of calculation method was verified by the test results. [PERSON] et al. [9] conducted sensitivity analysis on MIG welding parameters using response surface method. The calculation shows that the welding current and the welding speed have the most significant effect during the MIG welding of SUS301L-HT stainless steel, while the arc voltage has a relatively weak effect on the welding. [PERSON] [10] investigated the effect of heat input and welding speed on the weld pool shape and temperature distribution. The finite element code, ANSYS along with APDL command subroutines was employed to obtain the numerical results. The result shows that the predicted temperature distribution and the size of heat-affected zone are in good agreement. [PERSON] et al. [11] found out the effect of different welding methods on the residual stress distribution by means of neutron diffraction measurements and FE model simulation. Results show that residual stresses of MIG welding process are higher than those of friction stir welding process. This paper focuses on solving the deformation problem during MIG welding between the bottom plate and frame of power battery enclosure.