Computational evaluation of absorption characteristics of ceramic-based auxetic materials in X-band frequency range

Abstract

This research study investigates the absorption capabilities of ceramic-based auxetic metamaterials within the X-band frequency range, emphasising their potential application in stealth technology. Four distinct auxetic topologies have been chosen for this purpose: star, re-entrant, anti-tetrachiral, and missing-rib/cross-chiral while maintaining an equal cross-sectional area for comparison analysis. A computationally efficient homogenisation scheme based on the variational asymptotic method is used to evaluate the effective properties of these auxetics. The absorption spectra are then obtained by evaluating scattering matrices using these effective properties. The influence of auxetics out-of-plane thickness, incidence and polarisation angles on the proposed ceramic absorber’s absorption spectra is evaluated. One of the interesting observations is the identical absorption capabilities of star and missing-rib/cross-chiral geometries despite their distinct architectures. The star and missing-rib/cross-chiral based absorbers achieved a maximum absorption of 99.99% or a minimum reflection loss (RL) of −40 dB with a thickness of 3.50 mm. The RL is less than −10 dB (the standard for an electromagnetic (EM) absorber) for all incidence angles less than 70∘. The findings of this study hold significant potential for the advancement of ceramic-based auxetic metamaterials in EM absorption applications within the aerospace industry.