A novel reluctance electromagnetic riveting process: Multi-field coupling numerical and experimental studies

Abstract

This study proposes a novel reluctance electromagnetic riveting (REMR) process based on the magnetization of a ferromagnetic projectile, aimed at addressing the low energy conversion efficiency of traditional induction electromagnetic riveting (IEMR). A multi-field coupled electromagnetic-dynamic-mechanical finite element model was established, and an REMR experimental device was constructed. The driven head dimensions obtained from simulations and experiments matched well, with an error margin of within 6.3 %. By combining numerical simulations with comparative experiments against IEMR, the effects of seven key process parameters on REMR energy conversion efficiency was analyzed. The results revealed that REMR exhibits higher energy conversion efficiency, riveting force, and strain rate at lower voltages. For riveting Φ5 mm 2A10 aluminum alloy rivets to similar driven head dimensions, the voltage required by REMR was 145 V lower than that of IEMR, resulting in a 156 % increase in energy conversion efficiency. Furthermore, microstructural observation showed that REMR rivets undergo plastic deformation through an adiabatic shear mechanism, forming adiabatic shear bands (ASBs). The ASBs formed by REMR are narrower and exhibit more severe grain deformation compared to those formed by IEMR due to the increased strain rate.