Research on the Numerical Calculation Method for Antiloosening Performance of Screwed Joints under Complex Working Conditions

This study aimed at addressing the difficulties entailed in accurately determining the working loads of screwed joints (SJs) by establishing mechanical models and verifying the accuracy of the numerical calculation model of antiloosening performance under complex working conditions. First, considering the slip state of the interface and the stress state of the thread surface, a corresponding mechanical model was established to investigate the quantitative model of the interaction amongst structural parameters, complex working loads, and antiloosening performance of SJs. The applicability of existing models is expanded by this new model. Second, a load calibration test, an actual working condition test, and a dynamic simulation were combined to accurately determine the load under complex working conditions. A new experimental scheme for measuring the critical residual preload was employed to verify the reliability and accuracy of the numerical calculation model. The results confirmed that structural safety is ensured and that accident risk is reduced. Finally, based on this model, the transverse load, axial load, bending moment, torque about the bolt axis, clamping eccentricity, loading eccentricity, and coefficient of friction in the thread and at the interface were analyzed in terms of the antiloosening performance. The results of this study are expected to provide significant guidance to engineering practices. Moreover, the numerical calculation model can accurately predict the antiloosening performance and failure and also provide technical support for improving the structural reliability, particularly for key screwed-joint structures (SJSs), under complex working conditions loading.