PNNL

Abstract

In recent years there has been interest in better understanding the electromagnetic forming (EMF) process with a goal of expanding its use beyond the small and axisymmetric shapes that dominate the industry. The main driver for this interest has been the auto industry desire to increase the use of aluminum in automobiles. In traditional automotive stamping processes, aluminum is generally less formable than steel. The high velocities achieved in EMF result in enhanced formability. In EMF an electromagnetic driving force results from eddy currents in the work piece that are induced by a transient magnetic field generated by a nearby coil. A mathematical treatment of the electric and magnetic fields results in Maxwell's equations. The deformation and thermal response of the materials is strongly coupled to the electromagnetic fields. Hence a multiphysics environment exists requiring simultaneous trreatment of models based on Maxwell's equations, finite deformation elastoplasticity or elastoviscoplasticity, as well as adiabatic heating. As Maxwell's equations are significantly affected by the deformation field in the deforming medium, an incremental formulation of the boundary-value problem of electromagnetics is required. This, along with a conventional metal plasticity model and finite deformation mechanics, render this simulation environment computationally intensive. In this paper we describe the theoretical and numerical challenges associated with the numerical solution of Maxwell's equations in deforming media. A non-exhaustive review of existing capabilities for such solutions is presented. Different theoretical/numerical approaches to the problem are discussed and finally we discuss the future modeling needs for the advancement of EMF as a manufacturing process.