Analytical and Numerical Analysis of Stress Concentration Singularities in Perforated Composite Wing Ribs

Abstract

Aeronautical structures commonly use perforated skin panels and wing ribs to reduce weight while maintaining satisfactory mechanical performance. However, the combined influence of aperture size, material anisotropy, and fiber orientation on global and net stress concentration factors in orthotropic composites remains insufficiently quantified. This work aims to analyze the stress concentration behavior of perforated panels made of isotropic and orthotropic composites. A uniaxial tensile load is modeled using the finite element method (Abaqus) and classical analytical models (Heywood, Lekhnitskii, and Green-Zerna), supplemented by parametric calculations in MATLAB for glass/epoxy and carbon/epoxy plates. The results show a maximum stress concentration factor of K_tg ≈ 6.6 for a geometric ratio d/W = 0.5 under an applied stress of 10 MPa, with a maximum error of 5% between the analytical and numerical models. A reduction of approximately 60% in the concentration factor is observed for a fiber orientation of 0°. Finally, the study proposes global and local stress concentration maps that incorporate fiber geometry/orientation compatibility limits, enabling the optimization of composite wing ribs while preserving the advantages of lightness, stiffness, and control of local stress amplifications, and opening up prospects for the study of damage and fatigue.