Numerical Simulation And Process Research For Electromagnetic Forming High-strength Steel Metal

In purpose of reducing energy consumption and environment pollution, light-weighting of structure and material has become the mainstream of modern technologicaldevelopment. And the effective method and technological approach for automobilelightening is the utilization of high strength and high performance steel sheets.However, there exists some forming problems, for instance, high yield strength,superfluous spring back, easier cracking, more wrinkling and warping, for the reasonthat forming property of high strength steel panel presents inferior at roomtemperature. Therefore, it is hard for traditional cold-forming process to adoptadvanced high strength steel panel in the procession of auto body parts withcomplicated structure and shape. Electromagnetic forming (EMF) is a high-speed(strain rates=103/s~104/s) and impulse forming technology. Compared withconventional rigid mold forming process, EMF has the advantages of no contact, lessspring back, higher forming limit, good combination of other technology and so on,which may contribute a lot to cold-forming of advanced high strength steel in aneffective way.Electromagnetic forming of high strength steel must be with the aid of driverplate made of high electric conductivity materials due to its low electric conductivity.The driver plate has impacts on sheet in both force and collision. In this paper, DP600sheet was indirect loaded with driver plate. The deformation process of sheet anddriver using Johnson-Cook constitutive model under pulsed electromagnetic forcewas simulated, including circuit analysis, electromagnetic field analysis and dynamicdeformation analysis of sheet and driver plate structure, in other words, analysis ofstructure field.By using the analysis module EMAG in ANSYS, discharge circuit simulationanalysis and3D electromagnetic field model of driver plate and planar spiral coilwere established. The simulation process analyses the induced current,magnetic field intensity, the result of electromagnetic simulation when the currentreached the maximum value and how electromagnetic force of5nodes on the radiusof driver plate change over time. ABAQUS explicit analysis method was introduced after reasonable docking of ANSYS and ABAQUS in order to establishthree-dimensional structure model of deformation process of driver plate and highstrength steel sheet under the effect of pulsed electromagnetic force. The results ofelectromagnetic deformation process of high strength steel were analyzed from theaspects of deformable contours, electromagnetic force and impact force,deformation velocity, effective strain and energy.In this paper, the effect of one technological parameter on electromagneticdeformation of high strength steel was analyzed systematically by maintaining otherfactors constant, including the thickness of driver plate, the space between driverplate and sheet, the space between driver plate and coil, shape of driver plate, thematerial of driver plate, die radius and coefficient of friction. The influence oftechnical parameters on sheet bulging height, the minimum thickness of sheet andeffective strain were analyzed, and provided some guidance on parameters selection.This paper discussed the effect of technical parameters by calculating the effectivestrain rate of nodes for the first time which provide references to the establishment ofconstitutive model considering strain rate response.