Experimental Research Of Hybrid Structure On Electromagnetic Riveting

As one of electromagnetic forming technology applications, electromagnetic riveting (EMR) is a new kind of riveting technology which transforms the electromagnetic energy to the mechanical energy. Compared with the traditional riveting, EMR is characterized by high loading rate of speed, rivet shaft expansion uniform and process quality consistency, which contribute to form hard deformation material and large diameter rivet. In this dissertation, EMR was systematically studied the technology by theoretical analysis, numerical simulation and experiments combination methods.The sequentially coupling method was adopted to analyze the EMR process. The electromagnetic field coupling model was established by using ANSYS / Multiphysics module. As boundary condition of electromagnetic field simulation result, the rivet deformation analysis model was established based on the high strain rate constitutive relation by using ANSYS / LS-DYNA module. The simulation results showed that the drive plate was mainly subjected to the axial magnetic force and the distribution of axial magnetic force was un-uniform along the driver plate radial direction. The magnetic force along the driver plate thickness was a gradient distribution. The rivet deformation of EMR composed of the whole free upsetting and the local free upsetting under the action of magnetic pressure and the deformation of rivet head can be divided into three zones, and these zones are the difficult deformation zone, the large deformation zone and the small deformation zone. The rivet deformation was determined by different parameters such as discharge voltage, discharge capacitance, system resistance, amplifier mass, rivet hole size and die form. The effective stress distribution of sandwich material subjected was un-uniform along the thickness direction under one-way loading, and the effective stress of formed rivet head side was larger than that of rivet countersunk head side. The effective stress distribution of sandwich material both sides subjected was larger than that of sandwich material middle position under two-way loading, and the interference of formed rivet both sides can be improved and the joining can be sealed.Based on process simulation experiment, the electromagnetic riveting experiment was done to realize the no damage riveting of composite. The effect of discharge voltage, riveting time was analyzed. The riveting of TA1 titanium alloy rivet can be realized successfully and the lamination and dehiscence were not observed to meet the technological requirements. Compared with the pneumatic riveting, electromagnetic riveting rivet shaft deformation was uniform and fluctuations were small. At the same time, microscopic joining of electromagnetic riveting was better than that of pneumatic riveting.The shearing and strong experiment was done to compared the electromagnetic riveting with the pneumatic riveting. A new typical part of the rocket was riveted by electromagnetic riveting technology.