基于自冲铆接（SPR）技术，从降低板材硬度和提高铆钉硬度两个角度，实现了对TA1钛合金薄板的有效连接，并制备了TH（降低板材硬度）和TR（提高铆钉硬度）两组钛合金自冲铆接头。通过力学试验研究了两组接头的静力学和疲劳性能，并且基于三参数经验公式采用S-N曲线拟合法绘制出接头S-N曲线。最后，从宏观角度分析两组接头的失效行为，并利用高真空扫描电镜（SEM）进行TR接头的微观断口分析。结果表明：从自冲铆接技术优势和工程实际角度考虑，TR接头的铆接方式比TH接头更具实际操作意义。TH接头的静失效载荷和能量吸收性能均优于TR接头；且两组接头的静力学失效形式均为铆钉断裂。而TR接头疲劳性能更优，且两组接头均出现了下板断裂和铆钉断裂的多种疲劳失效形式。此外，依据SEM观测结果推断出因下板断裂而失效的TR接头，其疲劳裂纹源于铆钉脚应力集中点，且首先沿板宽方向扩展，后沿板厚方向延伸，直至接头完全断裂失效。而因铆钉断裂而失效的TR接头，其断口呈现出典型的疲劳脆性断裂特征。
Based on self-piercing riveting (SPR) technology, the effective connection for TA1 titanium alloy sheets is realized. And TH and TR joints are fabricated with reducing the sheet hardness and raising the rivet hardness, respectively. The static and fatigue performances are studied, and the S-N curves are fitted using the S-N curve fitting method. Finally, the failure behaviors of the joints are analyzed in a macro perspective, and the micro fracture analysis for TR joints is conducted with a scanning electron microscope (SEM). The results showed that:TR joints are more practical than TH joints. The peak load and energy absorption value of TH joints are superior to those of TR joints, and their static failure modes are all rivet fracture. TR joints had a better fatigue performance than TH joints, they both failed because of locked sheet fracture or rivet fracture. Furthermore, it can be referred that the fatigue cracks of TR joints, which failed due to locked sheet fracture, initiated at the stress concentration point of the rivet feet, and extended along the sheet width direction first, and then along the thickness direction of the plate until the joints are completely broken. And the rivet fracture surfaces of TR joints are the typical fatigue brittle fracture characteristics.
[1] 何阳,屈孝和,王越,等. 钛合金的发展及应用综述[J]. 装备制造技术, 2014(10):160-161. HE Yang, QU Xiaohe, WANG Yue, et al. The development and application of overview of titanium alloy[J]. Equipment Manufacturing Technology, 2014(10):160-161.
[2] HE X C, GU F S, ANDREW B. A review of numerical analysis of friction stir welding[J], Progress in Materials Science, 2014, 65:1-66.
[3] HE XC, PEARSON I T, YOUNG K. Self-pierce riveting for sheet materials:State of the art[J]. Journal of Materials Processing Technology, 2008, 199(1-3):27-36.
[4] CALABRESE L, PROVERBIO E, POLLICINO E, et al. Effect of galvanic corrosion on durability of aluminum/steel self-piercing rivet joints[J]. Corrosion Engineering Science and Technology, 2015, 50(1):10-17.
[5] CALABRESE L, PROVERBIO E, POLLICINO E, et al. Failure behavior of SPR joints after salt spray test[J]. Engineering Structures, 2015, 82:33-43.
[6] KANG S H., KIM H K. Fatigue strength evaluation of self-piercing riveted Al-5052 joints under different specimen configurations[J]. International Journal of Fatigue, 2015, 80:58-68.
[7] DI FRANCO G, FRATINI L, PASTA A. Fatigue behavior of self-piercing riveting of aluminum blanks and carbon fiber composite panels[J]. Proceedings of the Institution of Mechanical Engineers Part L-Journal of Materials-Design and Applications, 2012, 226(3):230-241.
[8] MUCHA J. The effect of material properties and joining process parameters on behavior of self-pierce riveting joints made with the solid rivet[J]. Materials and Design, 2013, 52:932-946.
[9] MUCHA J. The numerical analysis of the effect of the joining process parameters on self-piercing riveting using the solid rivet[J]. Archives of Civil and Mechanical Engineering, 2014, 14:444-454.
[10] GAY A, FABIEN L, SEBASTIEN B, et al. Fatigue performance of a self-piercing rivet joint between aluminum and glass fiber reinforced thermoplastic composite[J]. International Journal of Fatigue, 2016, 83:127-134.
[11] ZHAO L, HE X C, XING B Y, et al. Influence of sheet thickness on fatigue behavior and fretting of self-piercing riveted joints in aluminum alloy 5052[J]. Materials and Design, 2015, 87:1010-1017.
[12] HUANG L, JOHN B, JOHN L, et al. Fatigue and fretting of mixed metal self-piercing riveted joint[J]. International Journal of Fatigue, 2016, 83:230-239.
[13] HUANG L, SHI Y D, GUO H D, et al. Fatigue behavior and life prediction of self-piercing riveted joint[J]. International Journal of Fatigue, 2016, 88:96-110.
[14] ZHANG X L, HE X C, XING B Y, et al. Influence of heat treatment on fatigue performances for self-piercing riveting similar and dissimilar titanium, aluminum and copper alloys[J]. Materials and Design, 2016, 97:108-117.
[15] MA Y W, LI Y B, HU W, et al. Modeling of friction self-piercing riveting of aluminum to magnesium[J]. Journal of Manufacturing Science and Engineering, 2016, 138(6).
[16] KIM K W, KIM D, CHO H Y. Finite element analysis for design of divided shank of self-piercing rivet[J]. Journal of Welding and Joining, 2016, 34(2):54-58.
[17] 何晓聪,何家宁,柯建宏,等. 自冲铆接头的质量评价及强度可靠性预测[J]. 湖南大学学报, 2010, 37(12):1-4. HE Xiaocong, HE Jianing, KE Jianhong, et al. Quality evaluation and strength reliability prediction of self-pierce riveted joints[J]. Journal of Hunan University, 2010, 37(12):1-4.
[18] 高镇同,傅惠民,梁美训. S-N曲线拟合法[J]. 北京航空航天学报, 1987, (1):115-119. GAO Zhentong, FU Huimin, LIANG Meixun. A method for fitting S-N curve[J]. Journal of Beijing University of Aeronautics and Astronautics, 1987, (1):115-119.
