Abstract Friction self-piercing riveting (F-SPR), as a combination of traditional self-piercing riveting and friction stir spot welding processes, has been proposed to solve the cracking issues in riveting low ductility materials. The F-SPR process creates mechanical and solid-state hybrid joints, which are quite different from existing spot welding/joining methods. However, the roles that mechanical interlocking and solid-state bonding play upon the mechanical behavior of the joints are unknown. To fill in this gap, the current body of work investigated the tensile-shear behavior and fracture mechanism of the F-SPRed AA7075-T6 aluminum alloy sheets. The results reveal that the ring-shaped solid-state bonding between aluminum sheets enhances the overall stiffness of the joints but shows a minor contribution to the tensile-shear performance. The solid-state bonding formed between the captured aluminum in the rivet shank and the lower sheet serves as an “anchor” to hinder the rotation of the rivet, which delays the action of rivet pull-out from the lower sheet and thus strengthens the joints significantly. The combination of a hard rivet, large rivet flaring and solid-state bonding inside the rivet shank is necessary to achieve the preferred rivet pull-out fracture mode, which shows a higher peak load and larger energy absorption compared to other fracture modes.

中文翻译：

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机械和固态连接特性对摩擦自冲铆接铝合金AA7075-T6接头拉剪性能的影响

摘要 摩擦自冲铆接（F-SPR）作为传统自冲铆接和搅拌摩擦点焊工艺的结合，已被提出来解决铆接低延展性材料时的开裂问题。F-SPR 工艺创建机械和固态混合接头，这与现有的点焊/连接方法大不相同。然而，机械互锁和固态粘合对接头机械行为的作用尚不清楚。为了填补这一空白，目前的工作主体研究了 F-SPRed AA7075-T6 铝合金板的拉伸剪切行为和断裂机制。结果表明，铝板之间的环形固态结合提高了接头的整体刚度，但对拉伸剪切性能的贡献很小。铆钉柄中被捕获的铝与下板之间形成的固态结合作为“锚”阻止铆钉旋转，从而延迟了铆钉从下板拉出的动作，从而加强了接头显着地。硬铆钉、大铆钉扩口和铆钉柄内的固态结合是实现首选铆钉拔出断裂模式所必需的，与其他断裂模式相比，该模式显示出更高的峰值载荷和更大的能量吸收。