Numerical Simulation And Experiment Of Electromagnetic Riveting And Joint Mechanical Property

Electromagnetic riveting (EMR) is a new riveting process, with thecharacteristics of high-energy load and forming in microseconds. Uniform amountof interference can be formed along the entire shank. This method can improveriveting quality, and provide effective solutions to composite material connectionsand titanium alloy or large diameter rivets forming. In this dissertation, high strainrate material models were constructed. The electromagnetic riveting numericalsimulations including electromagnetic field analysis and rivet deformation andtemperature coupling analysis, and joints shear strength test numerical simulationwere studied. Electromagnetic riveting experiments and riveted joints shear strengthtests were conducted. The impacts of process parameters on the rivet forming andjoint strength were analyzed in the combination of simulation and experimentresults.Dynamic compressive properties of2A10aluminum alloy at room temperatureand the heating state were obtained by split Hopkinson pressure bar tests. Withquasi-static mechanical test results, Johnson-Cook material model of2A10aluminum alloy and exponential model of5083aluminum alloy were constructed fornumerical simulation.Numerical simulation of electromagnetic field was studied by ANSYS/MULTIPHYSICS module. The results showed that under the equiva lent condition incapacitance, peak magnetic pressure was increasing with the continuous increase ofthe discharge energy, and intensity decay rate of magnetic pressure was increasingfrom the drive-chip center to the sides. Under the equivalent conditions in dischargeenergy, discharge cycle was increasing, and greater momentum for rivet wasprovided as the capacitance increased.Numerical simulation of rivet deformation-temperature and riveted joints sheartest were studied by ANSYS/LSDYNA module. The results showed that severaldeformation zones appeared in the rivet deformation process. In the high strain rateconditions, rivet upset head showed the characteristics of deformation localization,and formation of shear bands for the combined effects of strain and strain ratehardening effect, and temperature softening effect. Rivet deformation completiontime was greater than the time of the magnetic pressure. Under the equivalentconditions in capacitance with the discharge of energy increasing, and under theequivalent conditions in discharge energy with the capacitance increasing, the heightof upset head was decreasing, and the diameter of the rivet upsetting head, theinterference of nail, and residual stress values of riveted plates were increasing. The shear test simulation results showed that riveted structure damaged in the form ofrivets rupture. Rupture area was in the riveted plate at the junction. Under theequivalent conditions in capacitance with the discharge of energy increasing, andunder the equivalent conditions in discharge energy with the capacitance increasing,the riveted joint strength was continuously increased.Electromagnetic riveting experiments under different processing parametersand riveted joints shear performance tests were conducted. The influences ofdifferent process parameters on the upset head deformation size, the amount ofinterference, as well as the joint shear strength were studied with experiment resultsand the profile and metallographic observation of rivets. The experiment resultswere compared with the numerical simulation results. Size deviation of rivet upsethead height was less than1mm. Deviation of rivet diameter was less than1%.Deviation of rivet diameter was less than1%. Deviation of interference amount wasless than3%. Deviation of riveting joint strength was less than10%. The laws ofexperiment results and simulation results were consistent. Therefore, the simulationresults closely reflected the experimental results.