The accuracy of numerical simulations of bolted joints depends on the correct modelling of thread geometry and the selection of an appropriate numerical model. Manufacturing tolerances and different modelling approaches may lead to significant differences in the stress state; therefore, it is important to evaluate the influence of these factors on the accuracy of predicting stress distribution and load transfer within a bolted joint. The analyzed bolted joint consisted of an M20×2,5 mm bolt and nut of property class 10.9, designed in accordance with the relevant ISO standards. Finite element analysis was performed using SolidWorks and Abaqus software. Three numerical models were developed: an axisymmetric model, an axisymmetric model with flanges, and a three-dimensional model, in which different thread overlap conditions were analyzed. The results showed that reducing thread overlap increases local stresses at the roots of the first load-bearing threads, thereby increasing the likelihood of plastic deformation and crack initiation. Furthermore, the comparison of the models demonstrated that the three-dimensional model provides a more accurate representation of the actual behavior of the bolted joint by accounting for the thread helix and enabling the analysis of eccentric loading.
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