Prediction of stress distribution in press-fit process of interference fit with a new theoretical model

Interference fit is widely used in many industrial fields for its high ability to transmit an axial force or torque between a shaft and hub. But the performance of interference fits during their life in service is limited by stress concentrations and surface wear. Nowadays, theoretical methods based on thick-walled cylinder theory become increasingly abundant. However, the prediction results of stress distribution in press-fit process are not accurate for ignoring the stress concentrations. Since the stress distribution is significant for analysis of surface wear and assembly quality, especially for precision assembly of small parts, the purpose of this study is to build a new theoretical model to predict the stress distribution. The stress distribution equation was deduced based on a simplified model that a nonuniform linear load acts on a portion of semi-infinite plane. Finally, the stress distribution in the press-fit process was analyzed by the theoretical model, as well as the stress distribution of different material pairs (Ni36CrTiAl–50Ni-50Fe, AISI 1045–AISI 1045) under full contact condition. The comparison between theoretical and numerical results shows that the new theoretical model has high accuracy in predicting stress distribution and maximum stress, and the relative error is less than 17%. Therefore, the new theoretical model can give more reasonable results and provide a more reliable approach for design of interference fits. Furthermore, the model provides a method for the optimization of interference analysis under different structures and working conditions, and gives a theoretical basis for real-time estimation of assembly quality.