钢铝异种自冲铆接结构静载变形失效机制

Deformation failure mechanism under static loading on self-piercing rivetedstructure for dissimilar steel and aluminum

针对ST14冷轧钢与5083铝合金异种薄板组合自冲铆接结构在静态载荷作用下的变形失效机制开展研究。围绕钢铝异种自冲铆接成形质量进行对比分析,确定工艺参数。通过拉伸-剪切试验,分析搭接次序及铆点数量对接头静力学性能、瞬时刚度及失效行为的影响,探究静态载荷作用下钢铝异种自冲铆接接头的变形失效机制。结果表明:钢作上板时接头的成形质量、静力学性能以及瞬时刚度特性优于铝合金作上板时的接头。铆点数量的增加能够显著提升钢铝异种自冲铆接接头的性能,且对铝合金作上板时接头的提升效果更好。单点接头的静载失效形式均为铆钉与下板分离,双点接头的失效形式分别为双铆钉从ST14冷轧钢下板脱离以及5083铝合金下板断裂。接头失效后上板均发生翘曲变形,以塑性更好的材料作为上板,变形特征更明显,并能够获得更好的承载能力。铆点数量增加能够有效抑制板材塑性变形,并进一步提升接头的承载能力。

The deformation failure mechanism of self-piercing riveted structure for ST14 cold-rolled steel and 5083 aluminum alloy dissimilar sheet combination under static loading was studied.Then,the forming quality of steel-aluminum self-piercing riveting was compared and analyzed,and the process parameters were determined.Furthermore,by tensile-shear test,the influences of lap sequence and number of rivets on static mechanical properties,instantaneous stiffness and failure behavior of the joints were analyzed,and the deformation failure mechanism of the steel-aluminum dissimilar self-piercing riveted joints under static loading was investigated.The results show that the forming quality,static mechanical properties and instantaneous stiffness characteristics of the joints with the steel as upper sheet are better than that with the aluminum alloy as upper sheet.The performance of steel-aluminum self-piercing riveted joints can be improved significantly by increasing the number of rivets,and has a better effect on the joints with the aluminum alloys as lower sheet.The static loading failure modes of single-rivet joints are the rivet separated from lower sheet,and the failure modes of double-rivet joints are the rivet separated from ST14 cold-rolled steel lower sheet and the fracture of 5083 aluminum alloy lower sheet,respectively.The upper sheet is deformed after the failure of the joints,and the deformation characteristics are more obvious,and the better bearing capacity can be obtained when taking the better plastic material as the upper sheet.The increasing of the number of rivets can effectively restrain the plastic deformation of the sheet and further improves the bearing capacity of the joints.