investigation and numerical calculation of deformation in a three-layer panel with an irregular honeycomb core structure under external loading

Аuthors

Kotovich I. V.^1*, Vlasov D. D.²

1. Moscow Aviation Institute (National Research University), 4, Volokolamskoe shosse, Moscow, А-80, GSP-3, 125993, Russia
2. Mechanical Engineering Research Institute of the Russian Academy of Sciences, 4, M. Khariton'evskii per., Moscow, 101990, Russia

*e-mail: ilyakot@bk.ru

Abstract

This paper addresses the problem of determining the stress–strain state of three-layer sandwich panels with a honeycomb core containing local irregularities. The relevance of the research is driven by the widespread use of such structures in aerospace engineering, where an optimal balance between low weight and high stiffness and strength is critical, as well as the need to ensure reliability in the presence of defects or structural inhomogeneities. An analytical–numerical methodology is proposed, based on the first-order Timoshenko–Reissner theory for sandwich plates, expansion of the unknown displacement and rotation fields into double Fourier series, and the method of small perturbations to account for weak spatial variations in the shear stiffness of the core. The approach enables efficient incorporation of both simply supported boundary conditions and external mechanical loading, as well as thermal gradients. The thermal effect is modeled through equivalent bending moments proportional to the temperature difference between the face sheets. The experimental component includes tes-ting of four panel specimens with varying honeycomb geometries under vacuum-induced uniform pressure; deformations were measured using the non-contact Digital Image Correlation (DIC) technique. Comparison between numerical predictions and experimental data demonstrates excellent agreement in terms of deflection fields, confirming the validity and practical applicability of the developed method. The proposed framework offers a reliable tool for the design and analysis of lightweight composite structures, enabling improved accuracy in structural assessment and potential weight reduction without compromising safety.

Keywords:

sandwich panels, honeycomb core, stress–strain state, irregular structure, method of small perturbations, double Fourier series, Timoshenko–Reissner theory, Digital Image Correlation

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