A Study on the Critical Thickness of the Inner Tube for Magnetic Pulse Welding Using FEM and BEM

Abstract

Due to high efficiency and quality in welding dissimilar metals, Magnetic Pulse Welding (MPW) has attracted much attention. In this study, 3A21 aluminium alloy used as outer tube was welded to 20Fe tube by MPW. In order to investigate the critical thickness of the inner tube (20Fe) which is subjected to huge impact pressure from the outer tube (3A21), both numerical simulations and experiments were carried out. For the purpose of investigating the critical thickness of the inner tube under various impact velocities, four discharge voltages (9 kV, 11 kV, 13 kV and 14 kV) were employed in the MPW experiment. The diameters of inner tube at different locations were measured to obtain its plastic deformation at various discharge voltages. The simulations considering the coupled effects of the mechanical, thermal and electromagnetic process were performed to research the impact velocity and deformation of tubular fittings in the electromagnetic module (EM) in LS-DYNA. An inverse method was proposed to find the dynamic yield stress of inner tube, and the predicted yield stress was then employed in models with critical thickness. Both of the impact velocity and deformation were verified experimentally.