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Self-piercing riveting (SPR) has been used to join similar and dissimilar materials for vehicle body application. In order to understand the failure mechanism and develop a method to estimate the shear strength of SPR similar and dissimilar materials, finite element modeling was conducted in this study. In the modeling, the contact conditions between the rivet and the workpieces were taken into account to establish the failure criteria of SPR of steel and aluminum sheets. It was found that the failure procedure of riveted dissimilar materials was different from that of riveted similar materials. Furthermore, the experiments were conducted to validate the modeling results. It was shown that the shear strength and failure mode of SPR joints were in agreement with the modeling results. These results suggested that the model could be used to estimate the shear strength of SPR joints. The factors influencing the failure mode and shear strength of SPR joints were discussed in detail. For rivet pull-out mode, the rivet open angle at the upper sheet, friction coefficient between the rivet and sheet, and the yield strength of the substrate were the key factors. For sheet tearing mode, failure occurred at the weaker sheet and the shear strengths mainly depended on the sheet gage and strength grade of the weaker sheet. [ABSTRACT FROM AUTHOR]

The zirconium alloy cladding tube and end plug used for nuclear fuel rods are usually joined by pressure resistance welding. And the service performance of the fuel rod cladding is directly influenced by the welded joint. In order to understand the forming process deeply, an axisymmetric electro-thermal–mechanical process finite element model was established in this paper. The current density distribution, temperature field evolution, and joint forming process during pressure resistance welding were all simulated by this model. It was shown that due to the contact resistance, a concentrated heat flow was rapidly generated on the tube-plug contact surface caused by welding current. A heat conduction was established on both sides of the welding surface. The high-temperature region on the side of the cladding tube was larger than the end plug. The metal of the tube extruded to both inside and outside of the joint under the coupled loading of heat and pressure. The location of the highest instant temperature on the welding surface moved from the inside to the outside of the joint. The highest temperature was 1568 °C, not reaching the melting point of zirconium alloy. The joining area and the highest temperature increased with welding current increasing, the welding time had little effect on them. Based on the numerical model, two structural design schemes to improve the joint forming quality were proposed. They were expected to provide a guide line for the joint design. [ABSTRACT FROM AUTHOR]