Theoretical Calculation and Experimental Verification of Wear Prediction During the Tightening Process of Bolted Joint

Abstract

Thread seizure is a common failure mode for bolted joints during the process of tightening, significantly influencing their reliability and detachability. Research results have demonstrated that the accumulation and blocking of wear debris are the main reasons for thread seizure. This study proposed a theoretical model to predict the wear volume on thread surface in the tightening process for the first time. First, many sub-regions on the thread surface were divided. The real contact force and area on each region were calculated considering the nonuniform axial load distribution in a bolted joint. Second, for each sub-region, the micro morphology was characterized by fractal function. Based on the fractal contact theory, the contact model of single asperity was built, and the contact force and area of single asperity were calculated in the stages of elastic, elastoplastic, and plastic deformations. Subsequently, the contact force and contact area of each sub-region were obtained by integral on single asperity. The former was compared with the contact force of sub-region calculated by nonuniform axial load distribution to determine the termination condition of iteration. The latter was brought into the wear prediction model based on Archard wear theory. According to the theoretical model of predicting the wear volume on thread surface, the effects of axial load distribution coefficient, preload, fractal parameters, friction coefficient, and thread pitch on the wear volume of thread surface were analyzed and discussed. Finally, experiments were conducted to validate the reliability of the proposed theoretical prediction model for wear volume.