Electromagnetic riveting process (EMR) is a high-speed impact connection technology with the advantages of fast loading speed, large impact force and stable rivet deformation. In this work, the axisymmetric sequential and loose electromagnetic-structural coupling simulation models were conducted to perform the electromagnetic riveting process of a Ti-6Al-4V titanium rivet, and the parameter analysis of the riveting setup was performed based on the sequential coupled simulation results. In addition, the single-objective optimization problem of punch displacement was conducted using the Hooke–Jeeves algorithm. Based on the adaptive remeshing technology adopted in air meshes, the deformation calculated in the structural field was well transferred to the electromagnetic field in the sequential coupled model. Thus, the sequential coupling simulation results presented higher accuracy on the punch speed and rivet deformation than the loose coupling numerical model. The maximum relative difference of electromagnetic force (EMF) on driver plate and radial displacement in the rivet shaft was 34.86% and 13.43%, respectively. The parameter analysis results showed that the outer diameter and the height of the driver plate had a significant first-order effect on the response of displacement, while the platform height, transition zone height, angle, and transition zone width of the amplifier presented a strong interaction effect. Using the obtained results on the optimal structural parameters, the punch speed was effectively improved from 6.13 to 8.12 m/s with a 32.46% increase. Furthermore, the displacement of the punch increasing from 3.38 to 3.81 mm would lead to an 80.55% increase in the maximum radial displacement of the rivet shaft. This indicated that the deformation of the rivet was efficiently improved by using the optimal rivet model.

As a main component of the magnetic pulse welding (MPW) system, the working coil exerts a great influence on the electromagnetic force and its distribution, which, in turn, affects the quality of the MPW joints. This study proposes a structural parameter optimization of the MPW coil, with the objective of achieving a higher induced current density on the flyer plate. The optimal Latin hypercube sampling technique (OLHS), Kriging approximate model, and the Non-Linear Programming by Quadratic Lagrangian (NLPQL) algorithm were employed in the optimization procedure, based on the finite element model built in LS-DYNA. The results of the sensitivity analysis indicated that all the selected parameters of the coil had a specific influence on the induced current density in the flyer plate. The optimized coil structure serves to refine the pulse current flowing path within the coil, effectively reducing the current loss within the coil. Additionally, the structure reduces the adverse effect of the current within the coil on the induced current within the flyer plate. Numerical results show the peak-induced current of the flyer plate increasing by 25.72% and the maximum Lorentz force rising by 58.10% at 25 kJ with the optimized coil structure. The experimental results show that with the same 25 kJ discharge energy, the optimized coil could increase the collision velocity from 359.92 m/s to 458.93 m/s. Moreover, 30 kJ of discharge energy should be needed to achieve the failure mode of base material failure with the original coil, while only 15 kJ should be applied to the optimized coil. These findings verify the optimization model and give some outline for coil design.

: With the increasing applications of multi-material structures in lightweight vehicle, traditional joining techniques are highly challenged in joining dissimilar materials. To meet the multimaterial structures requirements of lightweight design, electromagnetic joining (EMJ) technology, including electromagnetic riveting (EMR) and magnetic pulse welding (MPW), developed rapidly in recent years, which can achieve good connection performance for complex-shaped structures and dissimilar materials. This paper presents a comprehensive review of the research progress of the EMJ technology in China. Moreover, this review aims at providing a guideline for researchers engaged in electromagnetic joining technology and other connecting processes to further improve the level of lightweight vehicle design and manufacture. Firstly, the development history and status of EMJ were presented. Then the basic joining principles and characteristics of EMR and MPW were analyzed in detail. Subsequently, the investigation of joints formation mechanism, mechanical properties of joints and equipment development of EMR and MPW techniques were reviewed and analyzed. Specially, the operating principle is described along with various factors affecting the mechanical and microcosmic properties of joints. Finally, the future development trend of the EMJ technology based on the current research progress is highlighted.