Analysis of Forced and Free Vibration Characteristics of Laminated Conical Shells and Combined Shell Structures

This study presents a comprehensive investigation into the vibration characteristics of composite laminated conical shells and combined structures through the integration of laminated thin shell theory and spectral element method. The dynamic model of the combined shell structure is constructed by combining the boundary conditions of individual conical shells and the variation of semi-vertex angles. A novel vibration analysis methodology is formulated, establishing the dynamic stiffness matrix for multi-layered conical shell structures. The validity of both the computational framework and dynamic modeling approach has been rigorously verified through comparative analyses of natural frequencies and vibration responses against finite element method (FEM) simulations, demonstrating excellent agreement. The systematic parametric investigation examines critical factors influencing vibrational behavior, including: elastic boundary constraints at shell extremities, ply orientation angles, number of laying layers and semi-vertex angle configuration. Key findings reveal that ply orientation and boundary stiffness significantly influence natural frequency spectra. Semi-vertex angle variation demonstrates frequency-dependent effects, where increased semi-vertex angles induce progressive downward shifts in resonance peaks toward lower frequency ranges. The developed methodology offers valuable analytical tools for vibration prediction and parametric optimization in laminated conical shell and combined shell structures design. This research particularly contributes to the accurate modeling of complex boundary conditions and anisotropic material effects in composite shell structures, providing essential insights for aerospace, mechanical, and civil engineering applications requiring precision vibration control.