Vibrations of Bolted Flange Conical–Cylindrical Shells in Thermal Environment

Bolted thin-walled structures under temperature gradient conditions are widely used in engineering applications, but their vibration behavior has not been systematically studied. This paper investigates the vibration characteristics of conical–cylindrical shells (CCSs) with bolted flange boundary under temperature gradient conditions. A lumped-parameter model incorporating interface contact pressure is employed to characterize the mechanical properties of bolted flange connections, enabling the derivation of theoretical stiffness expressions. The theoretical framework integrates the first-order shear deformation theory, bidirectional thermal gradients, and temperature-dependent material degradation, with the governing equation derived via the Lagrange equation. To validate the model, a dedicated experimental platform with temperature gradient conditions is developed. The effects of key parameters on vibration characteristics are investigated, including temperature gradient direction, flange dimensions, cone angle, and structural parameters. The proposed framework provides the first validated methodology for predicting thermally induced vibrations in bolted CCS, offering critical insights for vibration-resistant designs in thermal environments.