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The behaviour of a self-piercing riveted connection was investigated experimentally and numerically. An extensive experimental programme was conducted on elementary riveted joints in aluminium alloy AA6060 in two different tempers, T4 and T6. The experimental programme was focused on the influence of important model parameters such as thickness of the plates, geometry of the specimens, material properties of the plates and loading conditions. An accurate 3D numerical model of different types of riveted connections subjected to various loading conditions was generated based on the results of the numerical simulation of the riveting process. A new algorithm was generated in order to transfer all the information from the 2D numerical model of the riveting process to the 3D numerical model of the connection. Thus, the 3D model was initialized with the proper deformed shape and the current post-riveting stress-strain state. The residual stresses and the local changes in material properties due to the riveting process were an important factor in order to get the correct structural behaviour of the model. The simulations have been carried out using the explicit finite element code LS-DYNA. The model was validated against the experimental results in order to get the correct deformation modes and the force-displacement characteristics. The numerical force-displacement curves fitted the experimental ones with reasonable accuracy. Furthermore, the model seemed to be able to describe the correct structural behaviour and thus the failure mechanisms of the self-piercing riveted connections.

Many actions, such as accidental or malicious explosions, may impose high loading rates to structural frames. To enhance the knowledge of the behaviour of joints subjected to severe impulsive loading, a double-sided beam-to-column joint configuration was tested at quasi-static and dynamic loading rates. The test specimens consisted of H-section beams and columns, extended end-plates, and high-strength bolts. In both the quasi-static and dynamic tests, the fracture modes were bolt failure in combination with plastic deformation of the end-plates. However, it was observed that the joints absorbed considerably more energy before failure in the dynamic tests than in the quasi-static tests, partly due to changes in the deformation modes. Also, the ductility of the joints seemed to increase for higher loading rates. These results suggest that the tested joints behave in a preferable manner under extreme impulsive loads.

Thread failure of bolt and nut assemblies subjected to tension is generally undesired because it is a less ductile failure mode than fracture of the threaded shank of the bolt (denoted bolt fracture).Another issue is that incipient failure of the threads due to over-tightening is difficult to detect during installation. Thus, it is appropriate to investigate the causes of thread failure. A parameter that seems to govern the failure mode of bolt and nut assemblies, despite receiving limited attention in the literature, is the length of the threaded bolt shank located within the grip. This is particularly relevant for partially threaded bolts, where may be short. In the current study, direct tension tests were performed on M16 bolt and nut assemblies with different lengths . The tests showed that ≤ 9 mm resulted in thread failure, whereas ≥ 17 mm resulted in bolt fracture.For the intermediate range of , both failure modes were observed in replicate tests. Validated finite element simulations were conducted to gain insights into the mechanisms of failure. When was short, necking of the bolt occurred close to the nut so that the overlap between the threads of the bolt and the nut was reduced, which further induced thread failure. This paper suggests several practical approaches for reducing the probability of thread failure.

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