Publication Details
Abstract
Polymer composite materials (PCMs) are increasingly used in aircraft structures because of their high specific strength, low weight, corrosion resistance, and fatigue performance; however, their anisotropic behavior and susceptibility to progressive damage under complex loading complicate strength assessment and service-life prediction. This study investigates the mechanical behavior, strength characteristics, and durability of polymer composite materials used in aircraft structures and develops an approach for evaluating their performance under variable loading conditions. The mechanical response of unidirectional, symmetrically reinforced, and quasi-isotropic composite specimens was examined under tensile, compressive, bending, and interlaminar shear loading at different fiber-orientation angles. Experimental testing was combined with analytical calculations and finite element modeling in Abaqus to determine elastic moduli, Poisson’s ratios, stress distributions, deformation behavior, and failure characteristics. The Hashin failure criterion was applied and modified to assess damage initiation and strength limits in individual layers and multilayer composite packages. The results demonstrate a strong dependence of the mechanical properties and failure mechanisms on fiber orientation and loading direction. The calculated elastic and strength characteristics showed generally good agreement with the experimental behavior, while discrepancies at particular orientation angles were associated primarily with matrix-dominated failure, shear deformation, and fiber degradation under compression. Finite element simulations reproduced the characteristic deformation response observed experimentally and provided a basis for evaluating stresses within multilayer composite structures. Based on the combined experimental and numerical analysis, an approach for estimating periodic strength and forecasting the service life of aircraft polymer composite structures under variable loads is proposed. The findings can support more reliable strength assessment, damage prediction, and durability evaluation of load-bearing composite components used in aviation structures.