Method for loose bolt positioning and prediction of bolt axial force in bolt group

[Display omitted] •The mutual influence of the bolt axial force in the bolt group is revealed and the quantitative relationship model among the bolt axial forces in the bolt group is established.•The precise localization method for identifying loosened bolts in a bolted joint is presented.•A method is proposed for predicting the axial force of each bolt in a bolted connection in the event of a bolt loosening. Bolt-looseness reduces the stiffness of the structure and poses safety risks. The accurate monitoring of bolt axial force is crucial for ensuring the service performance of components. However, existing methods are less suitable for large-scale bolt axial force detection owing to unclear mechanisms of force interaction among bolts and limited vision-based detection methods for identifying slight angle loosening and cycle rotation. This paper proposes a bolt-set simulation model to investigate the influence of loose bolts on the axial force of tight bolts, and model the correlation between loose and tight bolts. Based on the established model, a method for accurately positioning loose bolts and predicting the axial force was developed and validated through experiments. The method's accuracy in locating the loosened bolt exceeds 99%, with the error between the predicted axial force and experimental results being less than 4%. The proposed method allows a more precise evaluation of structural health.