Modeling stick-slip in bolted joint tightening process

Abstract

Stick-slip affects torque-preload relationship during bolted joint tightening process. Its occurrence is not always possible to avoid and it can lead to an unreliable joint. In this study, tightening process was investigated and, in a first approach, modeled through theoretical analysis. In a second approach, experimental data was explored statistically using Analysis of Variance (ANOVA) and F-Test. Coefficient of global friction and stick-slip parameters were modeled and added to the first model. The final semi-empirical model was able to reproduce the variation of the friction and to predict stick-slip occurrence. Low errors were obtained in the comparison with experimental data for both cases, with and without the occurrence of stick-slip. The proposed semi-empirical model provides mathematical approach for accurately predicting stick-slip and its characteristics in a specific condition of bolt-nut surface treatment.