Performing an Indirect Coupled Numerical Simulation for Capacitor Discharge Welding of Aluminium Components

Abstract

Capacitor discharge welding (CDW) for projection welding provides very high current pulses in extremely short welding times. This requires a quick follow up behaviour of the electrodes during the softening of the projection. The possibilities of experimental process investigations are strongly limited because of the covered contact zone and short process times. The Finite Element Method (FEM) allows highly resoluted analyses in time and space and is therefore a suitable tool for process characterization and optimization. To utilize this mean of optimization, an indirect multiphysical numerical model has been developed in Ansys Mechanical APDL. This model couples the physical environments of thermal–electric with structural analysis. It can master the complexity of large deformations, short current rise times and high temperature gradients. A typical ring projection has been chosen as the joining task. The selected aluminium alloys are EN-AW-6082 (ring projection) and EN-AW-5083 (sheet metal). This paper presents the investigated material data, the model design and the methodology for an indirect coupling of the thermal–electric with the structural physic. The electrical contact resistance is adapted to the measured voltage in the experiment. The limits of the model in Ansys Mechanical APDL are due to large mesh deformation and decreasing element stiffness. Further modelling possibilities, which can handle the limits, are described.

Eddy Current Analysis in the Capacitor Discharge Welding

“…S. Chiozzi et al the fatigue lifetime of CDW welded bars of Inconel 718 and TiAl6V4 superalloys [6]. Numerous computer simulation work had been conducted to the CDW process; [7][8][9][10][11] as examples; none of them were found to deal with eddy currents generated in the welded parts. Based on the foregoing review, it would be clear that; among the considerable plentiful literatures carried out on the capacitor discharge welding process, no study was documented about the role of the eddy current in the process.…”

Case Study About Resistance Projection Welding of Aluminized Steel Parts

“…In projection welding the nut leg geometry is decisive for the joint resistance (the optimum value is less than 0.2mm) [4]. Due to the fast decrease in the yield strength value of the material during heating, many tests are required to adjust the right values of the welding parameters [5]- [7]. The surface preparation of the samples before welding is an important factor that affects the weld quality.…”