Deformation and strategy analysis of single-bolt and double-bolt assembly for aerospace engine casing connection systems

This article investigates the assembly deformation mechanism of single- and double-bolt preload conditions in the bolted joint system of aerospace engine casings. A theoretical model was established to describe nozzle center-of-mass displacement induced by bolt preload, validated through finite element simulations. Results demonstrate the model accurately predicts tail nozzle displacement trajectories and center-of-mass shifts during assembly. Utilizing this model, the study systematically analyzed how preload sequence, magnitude, and multi-step loading strategies affect assembly accuracy under single- and dual-bolt conditions. The study demonstrates that the preload sequence significantly influences assembly deformation, with rational loading methods effectively reducing center-of-mass displacement and residual deformation. Multi-step preloading significantly improves assembly accuracy compared to single-step loading. Although dual-bolt preloading is more challenging to control, its deformation patterns can be clearly elucidated. The findings provide the theoretical support for the design and process optimization of bolted structures in high-precision assembly scenarios.