Free vibration analysis of variable-stiffness composite cylindrical panels with complex cutout geometries

A unified computational framework for the free vibration analysis of variable-stiffness composite laminated cylindrical panels with complex cutout geometries, non-uniform thickness distributions, and multi-region laminates is presented. Based on first-order shear deformation theory, the framework enables the singledomain analysis of cylindrical panels containing multiple cutouts of arbitrary shape, without introducing independent subdomain fields or interface continuity constraints. Geometric complexity is handled through implicit level-set descriptions combined with high-order quadrature schemes, enabling accurate numerical integration over irregular domains. The accuracy of the framework is assessed through comparisons with high-fidelity finite element solutions, showing very good agreement with reference solutions across a range of benchmark configurations. Representative applications demonstrate its capability to analyse cylindrical panels with complex stiffness distributions and geometric discontinuities, and to investigate the influence of stiffness variability and cutout geometry on the dynamic response. For the configurations examined, the results show that stiffness tailoring through spatially varying fibre orientations enables mode-dependent tailoring of the natural frequencies of cylindrical panels with cutouts. Overall, the proposed framework provides an accurate and versatile tool for the vibration analysis of composite cylindrical panels with variable stiffness and complex cutout geometries, and establishes a sound basis for future developments in the design, optimization, and performance tailoring of advanced lightweight structures.