Assessment for structural stiffness and fatigue life on self-piercing rivet of car bodies

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Assessment for structural stiffness and fatigue life on self-piercing rivet of car bodies

Kim, Min Gun / Kim, Jin Hak / Lee, kun Chan / Yi, Won

Self-Piercing Rivet (SPR) has been spotlighted in the automobile industry as an alternative method to resistance spot welding and arc welding, and has drawn designers' keen interest as one of the potential lightening technology of the car body. Therefore the structural stiffness and fatigue life of SPR joint specimens was evaluated experimentally and numerically by FEM modeling in accordance with the FEMFAT guidelines. The tested SPR specimens showed that the rivets were disjoined from die-side sheet except for the Series E (5J32/SAPH), which exhibits the tear-type fracture of punch-side sheet from the rivets. This result implies that the thicker die-side sheet strongly hold the rivet rather than punch-side sheet. As a result, the tearing of punch-side sheet takes place. The Series E exhibits the highest riveting strength. The SPR specimens made up of aluminum-steel (Series B, C, D and E) show the higher riveting strength approximately 50% than that of aluminum-aluminum specimen (A series). Even though the structural stiffness of an SPR joint specimen is roughly the same with another type of joint, the fatigue life is different according to sheet material and its thickness. The results of numerical analysis are nearly identical to those of experiments. Thus, it can be that FEM modeling in accordance with FEMFAT is effective in assessing the stiffness and fatigue life of SPR joints, and can be an alternative to experimental analysis.