Analysis of the Variation of the Discharge Circuit Parameters During Electromagnetic Forming Processes

Discharge circuit parameters vary during the electromagnetic forming process. The variation of these parameters with time during the electromagnetic tube expansion is analyzed here. A coupled analytical model is developed to predict the parametric variation of discharge circuit and corresponding tube radial displacement. In the analytical model, discharge current updated in response to tube deformation at each time step. The electromagnetic forming experiment is performed on 1.5mm thick aluminum tube using 7 turns helical coil to validate the analytical model. Analytically estimated variation of inductance, resistance and the current waveform of the discharge circuit are well agreed with experimental observations. A 2D sequentially coupled simulation model is also developed using COMSOL, and the simulations results are compared with analytical and experimental results. It is observed that the error in estimated tube displacement is reduced from 17 to 9% when the dynamic nature of discharge circuit parameters is considered in the input excitation of the numerical model.