Buckling modeling and numerical validation of composite panels for sandwich structures

Sandwich structures with composite laminate panels have gained increasing prominence in the aerospace, automotive, and transportation industries, particularly in the design of high-performance components such as aircraft fuselages, automotive bodies, and transportation infrastructure. Their exceptional specific strength, stiffness, and improved structural stability make them critical in these industries for enhancing performance while reducing weight. However, accurately predicting their buckling behavior under compressive loads remains a significant challenge, as traditional isotropic plate models are often inadequate. To address this issue, this study develops an innovative theoretical buckling model for composite laminate sandwich panels, integrating the stress function method with first-order shear deformation theory (FSDT) to capture the unique characteristics of laminated composites. The model produces exact closed-form solutions for global buckling and wrinkling, offering valuable insights into the underlying buckling mechanisms. A sufficiently broad range of material parameter ratios, including face-to-core stiffness ratio, thickness ratio, and aspect ratio, were selected based on realistic engineering conditions. The closed-form analytical solution was rigorously validated against a three-dimensional finite element model (FEM) of the laminated composite sandwich structure with orthotropic face sheets, demonstrating high agreement with FEM simulations, with a maximum deviation of less than 6%. This proposed approach provides a rapid and effective means for verifying numerical simulation accuracy, establishing a robust theoretical foundation for the design and optimization of composite structures.