Enhanced parameterization for variable stiffness laminated composite panels: Buckling optimization based on a semi-analytical model

Abstract

© 2026 The AuthorsDue to tailored stiffness distribution and enhanced performance, variable stiffness composites (VSC) have been a recent research focus. Variable angle tow (VAT) panels have improved buckling from curvilinear fiber paths within laminae. However, manufacturing still presents challenges. Overlaps and gaps are common in automated fiber placement (AFP); continuous tow shearing (CTS) may present irregular thicknesses. This work presents an alternative fiber tow path parameterization named the QP (quasi-parallel), inspired by fused filament fabrication (FFF), which generates offset curves from a reference path, minimizing overlaps and gaps, while maintaining constant thickness. Buckling performance is investigated for VAT and QP parameterizations, comparing optimal VSC to constant stiffness composites (CSC). Linear buckling of cylindrical panels is evaluated with a semi-analytical framework based on Sanders’ shell formulation and Rayleigh–Ritz solution, including compression-shear combinations, enabling efficient optimization. Numerous case studies are investigated, considering variations in loading, aspect ratio and panel curvature. Graphical search and simulated annealing (SA) optimization are employed to identify optimal designs. Both QP and VAT parameterizations show buckling improvement over CSC. The QP method delivers up to 40% increases for a square compressed plate. Advantages and limitations, such as the need for tow curvature constraint, are discussed for insights on VSC design.

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