A novel graded auxetic honeycomb core model for sandwich structures with increasing natural frequencies

Abstract

A novel angle graded auxetic honeycomb (AGAH) core is designed for sandwich structures in the present study. The angle of the cells is varied through the thickness of the AGAH core using linear functions. Therefore, the thickness of the cell walls is kept constant along the gradation of the cell angle, and the length of the cell walls is changed through the core thickness as the result of angle variation. New analytical relations are proposed to predict the equivalent elastic properties of the AGAH core. The performance of the new proposed core is analytically assessed for the vibrational behavior of a sandwich plate. The governing equations are deduced adopting Hamilton’s principle under the assumption of quasi-3D exponential plate theory. Three-dimensional finite element (3D-FE) simulation is accomplished to verify the analytical results of the vibrational response of the sandwich structure. The influence of variation of the cell wall, the cell angle and cell aspect ratio of AGAH core, and geometric parameters of the sandwich structure are investigated on the vibration response of the sandwich panel. The present graded design of the auxetic honeycomb enhances the specific stiffness (i.e., stiffness to density ratio) and consequently increases the natural frequencies of sandwich structures with this type of core.

Compressive properties of a modified re-entrant chiral auxetic structure (MRCA) under uniaxial quasi-static loading

“…Auxetic structures are a unique class that reveals negative values of Poisson's ratio (NPR) as results of their counterintuitive deformation behavior. Under uniaxial stretching or compression, auxetic cellular structures reveal lateral expansion or contraction, respectively [10][11][12][13][14][15]. Compared to the traditional materials/structures, it was stated that the auxetic feature (i.e.…”

Experimental and finite element analyses of a 3D printed sandwich with an auxetic or non-auxetic core

“…Xu and Deng 23 analytically determined the effects of negative Poisson's ratio and shear factor on the dynamic properties of auxetic and conventional thick cell structures, and also cite work on auxetic structures. 24,25 Following the large deviation theory, Wan et al 26 provided a theoretical method to determine the Poisson's ratio of honeycombs. Essassi et al 22,[27][28][29] extensively studied the static and dynamic behavior of bio-sourced sandwich structures with a re-entrant honeycomb core.…”

4D printed shape memory sandwich structures: experimental analysis and numerical modeling

“…For this purpose, additive manufacturing technologies are very beneficial in order to design and fabricate complex shape structures as well as metamaterial design with particular functionality [24,25]. In particular, if there is a need for energy and vibration damping, the new studies show that the application of auxetic structures with a negative Poisson's ratio can effectively improve the resistance and vibration properties and also increase the energy absorption rate of the structures [26][27][28][29][30]. In recent years, these structures, well-known as meta-sandwich structures, have been widely used for energy absorption applications such as sports equipment, protective packaging, or automotive protection parts [31,32].…”