Theoretical prediction model for residual preload of annular homogeneous multi-bolt group considering bolted joint stiffness and elastic interaction

Bolted joints are widely used in the connection of components in the aerospace industry. Due to the effect of elastic interaction, the preload of bolt joints will change. For this reason, establishing a prediction model of the residual preload of the bolt group is very essential. The model is based on the “spring-node” model and elastic interaction theory. This paper presents a theoretical prediction model of residual preload for single-step preload, multi-step preload and simultaneous preload of two bolts of a bolt group, which is capable of predicting the distribution of residual preload of a bolt group under any initial preload and tightening sequence. Meanwhile, the model was compared with the FEM model and the experimental model, and its prediction results were consistent, which completely proves the efficacy of the established prediction model of the residual preload force of the bolt group. In addition, the influence of system material constitutive and connection thickness on the residual preload of bolt group is also analyzed. Based on Matlab App Designer, a multi-bolt residual preload theoretical prediction modeling software system is developed, which can significantly improve the analysis efficiency and save economic costs. The residual preload prediction model of bolt group considering elastic interaction in this paper can provide a very effective reference for the design and optimization of bolt connection assembly process and the prediction of connection system performance in aero-engine.