A Numerical Investigation about the Effects of the Riveting Operation on the Strength of Joints

Abstract

A new interest has been increasingly directed in recent years to study the behaviour of joints provided with various kinds of fasteners and the mechanism of load transfer; profiting of the present capabilities of computing systems and analysis codes, which appear such as to deal with models built with more than one million elements, thanks to new numerical techniques which can solve huge systems of equations. However, the main interest has been limited to the case of bolted joints, for which several models are now available, while a few results are known for the case of riveted joints, where more complex mechanisms are involved. In the present paper a full set of analyses has been reported, with reference to both normal and blind rivets, where the manufacturing operation has been simulated through Ls-Dyna to evaluate the stress and strain states induced into the jointed sheets, varying the dimensional and riveting load characteristics of the joint. A subsequent investigation is presented, which aims to evaluate the effects of the compressed zone over the behaviour of an approaching crack.

About the Effects of Residual Stress States Coming from Manufacturing Processes on the Behaviour of Riveted Joints

“…In order to investigate on the influence of the riveting process, it has been necessary at first to transfer the residual stress-strain distribution around the hole coming from the riveting process, which was obtained by means of the FE explicit analysis of the riveting operation illustrated in [8], to the model of the riveted joint (sheets dim. 28.5 x 200 x 1 mm , hole diam.…”

“…3a) and in the subsequent recovery of the real interference as the first steps of the implicit FE analysis; some of the results obtained by using this technique are shown in figures 3 and 4 where rivet and sheets results coming from the implicit analysis after interference recovery (fig. 3b and 4a) can be compared with those obtained from explicit analysis [8] after riveting operation (fig. and 4b).…”

“…modelling and simulation of the riveting operation, with reference to a solid rivet; 2. development of bearing experimental tests in order to set-up numerical model of each sheet of the riveted joint (especially for what concerns material properties); 3. assessment of a numerical procedure to transfer stress/strain state from the FE explicit analysis of the riveting process to the FE implicit analysis of the joint structural behaviour; 4. investigation of the influence of the riveting process on the bearing resistance of a riveted joint. For what concerns the modelling and the simulation of the riveting operation, the adopted procedure is illustrated in [8].…”