Influence of pattern of stiffeners and cutouts on the stability characteristics of composite laminates under non-uniform load

Abstract

Perforated panels in thin-walled structural components often face stress concentration issues due to free edges, potentially leading to delamination or premature failure at lower stress levels. However, strategically placed stiffeners around the cutout can mitigate these failures. This study employs finite element analysis to assess how different stiffener arrangements affect the stability of composite laminates with cutouts under non-uniform edge loads. The analysis considers shear deformation and rotary inertia by modeling the panel skin and stiffeners with specific element types. Stiffener displacement is related to plate displacement through compatibility conditions, and various transformation matrices accommodate stiffener eccentricity and orientation. A new mesh configuration is implemented to explore different stiffener patterns around the cutout. A dynamic approach, utilizing two sets of boundary conditions, is adopted to solve buckling problems. The investigation evaluates diverse stiffener patterns under non-uniform edge loads and analyzes the impact of stiffener eccentricity and cutout dimensions. The study concludes that adjusting stiffener eccentricity within specific arrangements can significantly enhance perforated panel buckling strength and identifies optimal stiffener configurations for maximizing strength.