铝合金自冲铆接微动行为研究

选择两组不同厚度铝合金板制成SA15和SA25自冲铆接头并进行疲劳实验,用威布尔分布验证实验数据有效性,用疲劳三参数经验公式拟合接头S-N曲线并对比分析接头疲劳性能,用扫描电子显微镜研究接头微动行为以探索疲劳失效与微动磨损的关系。实验数据服从威布尔分布,表明数据可靠。三参数经验公式较好地拟合接头S-N曲线,SA25接头疲劳性能优于SA15接头,且在中低疲劳寿命区域SA25接头疲劳性能的优越性更为突出。SA15接头失效于上板靠铆钉头,而SA25接头失效于下板沿纽扣。SA15接头在铆接区两板间微动磨损较严重,SA25接头在下板与铆钉腿部微动磨损较严重。疲劳失效部位与微动磨损剧烈部位重合,表明微动磨损是导致接头疲劳失效的重要因素之一。

Fretting Behavior of Self-piercing Riveted Aluminum Alloy Joints

Two groups of Al alloy substrates with different thicknesses were selected to prepare SA15 and SA25 self-piercing riveted joints and fatigue tests were conducted. The validity of fatigue data was verified by two-parameter Weibull distribution. Fatigue behavior of the joints was analyzed by S-N curves, which were fitted by empirical formula of fatigue three-parameter. The relation between fretting wear and fatigue failure was investigated by a scanning electron microscope (SEM). The results revealed that experimental data were valid because of they obeyed Weibull distribution. S-N curves of the joints can be well fitted by the empirical formula, the fatigue performance of SA25 joints is superior to that of SA15 joints. SA25 joints have excellent fatigue performance during middle-low fatigue life domain. SA15 joints failed in the upper substrate near rivet head, and SA25 joints fractured at the bottom substrate along the button. SA15 joints appeared severer fretting behavior at the riveting interface between two substrates, while SA25 joints appeared severer fretting wear at the interface between bottom substrate and rivet leg. Fatigue failure position coincided with the severer fretting wear position, which reveals that fretting wear is one of the significant factors for the fatigue failure of the joints.