Simulation of electromagnetically formed joints

The most important application of electromagnetic forming (EMF) is joining by compression of tubular workpieces. The process simulation of such high speed forming steps must consider numerous mechanical, electrical, and electro-magnetic material characteristics and sometimes a even thermal dependency generally resulting in highly nonlinear computations. One of the most important interactions of the physical fields is the mutual dependency between the acting loads and the deformation. Consequently, a coupled field simulation of structure and magnetic field is demanded. In this paper an exemplary industrial joint produced by EMF is regarded. By comparative electromagnetic field simulations it is proved that the influence of the non-linear permeability of ferromagnetic materials in EM-forming problems is small. A three-dimensional coupled simulation of the joining process is carried out by help of an EM-module in a beta version of the LS-DYNA structural explicit code. To evaluate the quality of the resulting joint already in the virtual process design, the maximum transmittable moment is computed. An experimental verification of the forming and the testing procedure concludes the paper