Tensile and fatigue behaviour of self-piercing rivets of CFRP to aluminium for automotive application

Abstract

Numerical simulation and experimental validation of self-piercing riveting (SPR) of 6xxx aluminium alloys for automotive applications F Hönsch, J Domitner, C Sommitsch et al. Abstract. In this study, the tensile and fatigue behaviour of self-piercing rivets (SPRs) in carbon fibre reinforced plastic (CFRP) to aluminium 6111 T82 alloys were evaluated. An average maximum lap-shear tensile load capacity of 3858 N was achieved, which is comparable to metal-to-metal SPR lap-shear joints. The CFRP-Al SPRs failed in lap-shear tension due to pull-out of the rivet head from the CFRP upper sheet. The CFRP-Al SPR lapshear specimens exhibited superior fatigue life compared to previously studied aluminium-toaluminium SPR lap-shear joints. The SPR lap-shear joints under fatigue loads failed predominantly due to kinked crack growth along the width of the bottom aluminium sheet. The fatigue cracks initiated in the plastically deformed region of the aluminium sheet close to the rivet shank in the rivet-sheet interlock region. Scatter in fatigue life and failure modes was observed in SPR lap-shear specimens tested close to maximum tensile load.

Structural Stress Method to Evaluate Fatigue Properties of Similar and Dissimilar Self-Piercing Riveted Joints

“…The procedure employed was primarily based on the methods used by Hong [25] for spot welds. Since the fatigue failure mode in SPR joints are predominantly due to sheet failure [6,15,[26][27][28][29][30], which is similar to failure modes observed in spot welds, it is reasonable to apply the above methods for SPR joints. In our previous studies on dissimilar SPR joints [15,16], we have presented a single master S-N curve for lap-shear and cross-tension SPR joints using Rupp's structural stress method.…”

“…The introduction of CFRP in an automotive body structure can also result in weight savings of up to 10% greater than the use of aluminum and other lightweight metals and up to 50% savings when compared to steel [4,5]. Numerous studies have explored the feasibility of using SPR to join CFRP to aluminum alloys [6][7][8][9][10][11][12][13]. These studies have investigated the quality of the joint affected by die geometry [10], in-plane distance between the rivets [13], and oil pressure in a hydraulic system [11,12].…”

“…In addition to studying the joint quality solely based on the quasi-static testing, evaluating the fatigue life of weld and mechanical joints is a crucial exercise for the automotive industry in the early stages of vehicle development. However, while numerous studies have been performed on the fatigue characterization of SPR joints between similar materials (e.g., aluminum to aluminum), the fatigue characterization studies of CFRP to aluminum SPR joints are very limited [6,[14][15][16].…”

Fretting Behavior of SPR Joining Dissimilar Sheets of Titanium and Copper Alloys

“…An empirical model was developed to predict the joint strength in cross-tension loading using characteristic joint data determined directly from the SPR process (force-displacement) curve. The tensile and fatigue behavior of SPR in carbon fiber reinforced plastic (CFRP) to aluminum 6111 T82 alloys were evaluated by Kang et al [13]. The SPR lap-shear joints under fatigue loads failed predominantly due to kinked crack growth along the width of the bottom aluminum sheet.…”

Evaluation of CFRP/Steel/Aluminum Three Layer Joining with Self-Piercing Rivet

“…SPR 의 공정변수인 rivet, die, setting force를 변화하며 접합가능여부와 강도를 평가 11) 하였으며, SPR 접합 품 질판단을 위한 인자와 인장하중간의 상관관계를 분석 12) 하는 논문들이 발표되었다. 나아가 CFRP와 금속간의 SPR 이종접합 연구 13,14) 들이 진행되어 접합 가능한 소 재 범위가 한층 넓어지게 되었다. 이종금속의 3매 겹침 접합에서는 금속과 알루미늄에 대하여 소재와 공정변수 에 따른 접합성을 평가하는 연구 15,16)…”