Damage behavior and mechanical performance analysis of CFRP/DP590 joints in electromagnetic and conventional pre-holed self-piercing riveting processes

Self-piercing riveting (SPR) has been widely used as an effective joining method for carbon fiber reinforced polymer (CFRP)-steel hybrid structures in lightweight applications. However, CFRP damage always occurs during riveting process, affecting the mechanical performance of the joints. To address this issue, an electromagnetic pre-holed self-piercing riveting (EPH-SPR) technique was developed for high-quality CFRP/DP590 structures. A comparative analysis was conducted between EPH-SPR and traditional PH-SPR joints, focusing on joint cross-sectional morphology, material damage, microhardness, shear mechanical properties, and failure behavior. The finite element (FE) method was employed to explain the joining and damage evolution process of joints. Results demonstrated that the EPH-SPR showed a 16.1% increase in interlocking, achieving a 17.2% reduction in CFRP damage compared with PH-SPR joints. Electromagnetic loading promoted more uniform stress distribution in rivet legs, resulting in greater riveting force. For CFRP sheets, compressive damage was markedly more severe than tensile damage. The joint shear strength was increased by 15.6%, and the energy absorption capacity showed an improvement of 63.2%. The results showed that the increase of interlocking and the reduction of CFRP damage can significantly improve the mechanical properties of the joints. These demonstrated the advantages of the electromagnetic loading PH-SPR technique. These findings provide a solid theoretical foundation for improving joint quality and valuable insights for the optimization and technological advancement of related processes.