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Graphical abstract Abstract The self-piercing riveting (SPR) of 1420 aluminium–lithium alloy sheets is investigated. Static tests with lap-shear loads and fatigue tests using the tension–tension loading mode were applied to obtain the joint performances and failure modes. The mechanism analysis regarding failure and fretting was employed using a scanning electron microscope (SEM) and an energy dispersive X-ray spectroscopy (EDX). The 1420 Al–Li alloy sheets can be joined effectively using SPR. The fatigue load–fatigue life curve with a 95% confidence level is obtained using a variation coefficient method. The joints failed in the rivet pulled out from the locked sheet in static trials, and the locked sheet fractured during the fatigue tests. The fretting wear can be observed at the contact interface between the rivet tail and the locked sheet or between both sheets at different load levels. The fretting region changes at a high or low load level, and it is highly relevant to the fatigue rupture paths. [ABSTRACT FROM AUTHOR]

This paper reports on studies of the fretting behavior of self-piercing riveted (SPR) joints in titanium sheet materials. Experiments were performed on SPR titanium joints to help understand the influences of sheet thickness and fatigue load level on the fatigue strength and failure mode of the joints. Failed joints were examined using a Scanning Electron Microscope and an Energy Dispersive X-ray machine to study the fretting failure mechanisms of the joints. The results showed that increasing sheet thickness could improve the fatigue strength of the joints at high load levels but less so at low load level. Three failure modes were observed, the pierced sheet failure mode, the locked sheet failure mode and the rivet failure mode. The pierced sheet failure was mainly caused by the fretting wear at the interface between the rivet head and the pierced sheet. The locked sheet failure and rivet failure were generated by the fretting wear at the interface between the rivet shank and the locked sheet. Oxidized wear debris was observed on the surfaces of all the fracture regions of the joints. The main elements of the oxidized wear debris on rivet surfaces were Ti, Zn and O. [ABSTRACT FROM AUTHOR]

The fatigue performances of self-piercing riveting (SPR) joints connecting similar and dissimilar sheets of TA1 titanium alloy (TA1), Al5052 aluminium alloy (Al5052) and H62 copper alloy (H62) were studied in this paper. The specimens of similar TA1 sheets treated with stress relief annealing were prepared to investigate the influence of relief annealing on the mechanical properties of SPR joints. Fatigue tests were conducted to characterize the fatigue lives and failure modes of the joints. Scanning electron microscopy (SEM) was employed to determine the fatigue failure mechanisms of the joints. The results showed that stress relief annealing has an apparent impact on the fatigue performances but has little influence on the static strengths of the joints. For SPR joints in similar or dissimilar sheets, joints between similar TA1 sheets possess the best fatigue resistance, which are significantly higher than the joints in dissimilar sheets. In addition, most of the joints failed in the rivet and the locked sheet through fatigue tests, except the joints between TA1 and Al5052, which failed only in the locked sheets. [ABSTRACT FROM AUTHOR]

This paper deals with the mechanical properties of self-piercing riveted joints in similar and dissimilar metal sheets of Al5052 aluminum alloy and H62 copper alloy. Force–displacement curves and S – N curves were obtained to characterize the properties of joints. The normal hypothesis tests were performed to examine the rationality of the test data. The strength, stiffness, impact resistance, failure modes and failure mechanism of joints were also studied. Results showed that the fatigue strength of the joints is influenced by the properties of the sheet materials being joined. The existence of fretting might accelerate the initiation and propagation of the cracks or change the direction of fatigue cracking. Both static strength and fatigue strength of the joints increase with the enhancement of the joint stiffness. The failure model and failure mechanism are affected by the stiffness of the joints. [ABSTRACT FROM AUTHOR]