A FINITE-ELEMENT ANALYSIS OF THE ELECTROMAGNETIC TUBE-COMPRESSION PROCESS

The present study aims to analyse the wrinkling phenomena of the tube wall during the electromagnetic tube-compression processes. An analysis of dynamic plastic buckling during the high-velocity tube-compression process is developed. For this purpose, the initial radial imperfections of circular tubes were measured and used in an elasto-plastic finite-element analysis. The irregular buckling shapes along the circumferential direction can be traced by use of random phase angles. Also, by varying the phase angle along the axial direction, typical buckling shapes can be explained. As an application, the wrinkling reduction procedure with mandrels was analysed by introducing an impact-contact algorithm. In order to verify the validity of the present theory, experiments were carried out with pure aluminium tubes (Al 1050) of several different dimensions. The ratios of thickness to radius ranged within 9.29 - 37.68 and the heights were 35mm. The experiments were performed with various forming conditions, such as charging energies and mandrel diameters. The results of the analysis and of the experiments showed good agreement. It was found that the basic assumptions and the scheme of analysis of the present analysis are valid for the electromagnetic tube-compression process.