Coupling effects of loading state and loading rate on the nonlinear and failure behaviour of riveted joints: Experiments and modeling

Coupling effects of loading state and loading rate on the mechanical behaviour of a certain type of riveted joint are investigated experimentally and numerically. For the experiments, five types of riveted specimens including were designed to achieve various loading states. An advanced bi-directional electromagnetic split Hopkinson tensile bar system was utilized to achieve high loading rates. Subsequently, a micrographic analysis of the fractured rivets under different loading conditions was performed to understand the failure mechanism. The experimental results revealed a discernible influence of loading rate on the mechanical responses of the riveted joint, including yield force, ultimate force, energy absorption, and failure mechanism. Furthermore, it was observed that this loading rate effect exhibited a pronounced sensitivity to the loading state. Based on the physical deformation and failure mechanisms of the riveted joint, a novel simplified joint model incorporating the coupling effects of loading state and loading rate was developed. This model was further implemented into finite element program Abaqus/Explicit by adopting the user subroutine VUINTER. Through this approach, the mechanical responses of the riveted joints under different loading conditions were simulated using simplified numerical models. At last, a quantitative analysis was conducted by comparing the simulation results with experimental data. The analysis revealed a striking consistency between the simulated and experimental outcomes across various loading conditions, particularly in terms of the yield force, ultimate force and energy absorption. These findings indicate that the newly proposed joint model demonstrates excellent capability in characterizing the nonlinear and failure behaviour of the tested riveted joints over different loading states and a wide range of loading speeds. This work contributes to advancing the understanding of the complex mechanical behavior of riveted joints and provides a valuable tool for engineers to accurately predict and design the performance of riveted structures under various loading conditions.