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A non-destructive technique was proposed for geometrical parameters' measurement of self-piercing riveting (SPR) joints based on ultrasonic C-scan image. Firstly, in order to enhance the detection precision, the characteristics of the ultrasonic echo signal at the edge of internal structure were analysed, and a theoretical formula on its sound intensity distribution was established. Then, an image segmentation process for the detection of SPR expansion diameter was suggested. Results showed that taking the greyscale value at the 'inflection point' from the C-scan image as the threshold of the segmentation, the non-destructive test results can get good correlation with the metallographic cross section, which provides a new method on the quality evaluation of SPR by using non-destructive test. [ABSTRACT FROM AUTHOR]

In order to investigate the durability corrosion behavior and mechanical properties of steel aluminum heterogeneous self-piercing riveting adhesive joint (adhesively riveted composite joint) in salt environment, 0. 6 mol/L NaCl solution was used as corrosion solution to carry out the accelerated corrosion test of DP590-5052 adhesively riveted composite specimen by dry wet cycle immersion, combined with corrosion dynamics, statics and SEM. The results show that the loss of weight of the steel aluminum specimen increases all the time and the corrosion rate decreases gradually in the sat environment; at the initial stage of corrosion, the static strength and impact resistance of the butt joint in the sat environment have not been adversely affected; the sat environment has not changed the failure mode of the steel aluminum heterogeneous adhesive riveted composite joint, which s that the rivets are pulled off from the lower plate, and with the increase of corrosion time, a large number of hollows appear in the inner lock structure area. PIs and bulges affect the deformation characteristics of joints during failure. [ABSTRACT FROM AUTHOR]

In order to enhance the strength of adhesively bonded single-lap joints (SLJs), the adhesively bonded SLJs with reinforcements were proposed. Adhesively bonded SLJs of different substrates and with different reinforcements were investigated experimentally and numerically. Scanning electron microscopy was performed on the fracture surfaces of the joints to analyze the failure mechanism. Shear stresses and peeling stresses of the adhesive layer were calculated with finite element analyses (FEA). Results showed that the deformation of the joints decreased with an increase in stiffness at the end of the overlap region. The strength increase in adhesively bonded SLJs with reinforcements was validated by the results from experimental tests and FEA. [ABSTRACT FROM PUBLISHER]