Coupled finite element analysis of MIG welding assembly on auto-body high-strength steel panel and door hinge

Abstract

Automotive doors are assembled to auto-body side-frame through hinges by metal inertial gas arc-welding process. Because of thermal effect, the after-welding geometrical deformation of hinges seriously affects assembly accuracy of door position, causing functional problems such as poor sealing, abnormal sound during closing and opening, as well as large residual stress. In order to solve the complexity involved in auto-body arc-welding assembly process due to dynamic coupling between temperature field and structural field, a multi-field coupling finite element method employing the subroutine of commercial code ANSYS-APDL is proposed, and numerical analysis model is established in quantitative detail. Focusing on the arc-welding assembly process for the auto-body plate (which uses high-strength hot-dip galvanized steel), the promising lightweight material, and door hinge (which uses conventional low-carbon steel), moving heating source and birth–death element method are both adopted in this thermal–structural coupling analysis in order to obtain the complicated transient temperature distribution and mechanical stress behavior during the sequential formulation of arc-welding seam. Experiment is carried out to confirm the validity of this newly developed method, including temperature measurement by thermocouple and residual stress test by X-ray diffraction. The agreement between the experimental and numerical results is satisfactory, indicating the reasonability and feasibility of this method in lightweight auto-body assembly research. It can be concluded that the moving heating source multi-field coupling arc-welding model can strongly support the process parameters optimization for obtaining minimum weld deformation and residual stress.