A prediction model for axial installation force of interference-fit bolt in CFRP bolted joint and its deformation mechanism of contact interface at bolt-hole under static loading

This paper investigates the “brush-like” deformation phenomenon of the contact interface at the bolt-hole during the interference-fit installation of high-locking bolts under static loading in CFRP connection structures. An innovative theoretical model is proposed to predict axial installation force, specifically designed for moderate interference-fit. This model is based on the “brush-like” deformation of the hole wall, with the axial installation force predicted through force analysis and theoretical calculations, effectively overcoming the limitations of prior models that idealized the contact interface at the bolt-hole. The predictions generated by this theoretical model align closely with experimental data, confirming its efficacy in accurately forecasting the curve of installation force for interference-fit bolts during the static installation within the moderate interference-fit range. Additionally, a comprehensive analysis of the relationship between deformation of the hole wall and curves of installation force across small, moderate, and large interference-fit levels are presented. It is demonstrated that the degree of deformation within the moderate interference-fit range is more suitable than that in the small and large interference-fit ranges, making it a reliable alternative for installation force tests within this range during static installation. The moderate interference-fit domain [1.00%, 1.24%] is established as a validated and optimal range of interference-fit bolts for the static installation.