This paper investigates the vibrational characteristics of lattice-core sandwich annular spherical shells. An effective analytical model, based on the Smeared Stiffener technique, is employed to integrate the stiffness contributions of the core with those of the shells. Helical stiffeners are modeled as beams capable of bearing axial forces and bending moments. The governing equations are derived from Donnell's classical thin shell theory. The Galerkin method is applied to extract the natural frequencies. To validate the analytical results and conduct a comprehensive parametric study, a 3D finite element model is developed using ABAQUS CAE software. Comparisons demonstrate a satisfactory agreement between the analytical and numerical results. Additionally, the effects of the spherical shell's geometric parameters, lamination angle, stiffener orientation angle, and various lattice core configurations are examined.
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