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Keywords

Sandwich panel, Re-entrant auxetic core, Honeycomb structure, Free vibration, Natural frequency, Negative Poisson's ratio (NPR)

Document Type

Article

Abstract

In this paper, an analytical study is performed along with a numerical method to analyze free-vibration behavior of sandwich panels composed of aluminum face sheets and a polymer-based re-entrant auxetic core. An analytical model based on Classical Plate Theory (CPT) was formulated using equivalent orthotropic elastic properties derived from the re-entrant unit-cell geometry. Theoretical predictions were validated using three-dimensional finite element simulations in ANSYS 2025 R1, with SOLID186 elements under supported boundary conditions. The results indicate that if the core thickness is increased from 4 mm to 12 mm, there is roughly a 90% increase in the fundamental natural frequency. This trend is attributed to the significant enhancement in bending stiffness relative to the corresponding increase in mass, thereby improving the stiffness-to-mass ratio. Across core thicknesses up to 8 mm, high agreement was observed between analytical results and numerical results (1.27%–3.37%) for thin and moderately thick panels. When the thickness reached 12 mm, the deviation increased to 6.5%, indicating the growing influence of transverse shear deformation and rotary inertia, which are neglected in CPT. A comparison with a non-auxetic core of identical density (850 kg/m3) showed a 2.43% difference in the fundamental frequency, confirming that the negative Poisson's ratio mechanism alters the effective bending–shear interaction within the sandwich structure. The study demonstrates the potential of auxetic polymer cores to tailor dynamic performance. It provides an integrated analytical–numerical framework that enhances understanding of vibrational behavior in advanced lightweight sandwich structures.

DOI

10.30684/2412-0758.1547

First Page

1

Last Page

27

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