On wave propagation in piezoelectric-auxetic honeycomb-2D-FGM micro-sandwich beams based on modified couple stress and refined zigzag theories

Abstract

In the present paper, wave propagation of micro-sandwich beams is investigated. The sandwich beam is consisted of the core, top, and bottom layers which are corresponding to auxetic honeycomb, piezoelectric, and Two-Dimensional Functionally Graded Material (2D-FGM), respectively. The material properties of the 2D-FGM layer differ in both thickness and axial directions. The structure is under the electric field with respect to the existence of piezoelectric material. Giving the hypothesis of modified couple stress theory (MCST) for size effects and the refined zigzag theory (RZT) for mathematical modeling, the equations of motion are gained based on Hamilton’s principle. The wave velocity, escaping frequency, and cut-off frequency of the structure are computed through the analytical method. The influences of different components (e.g. geometric parameters, electric field, auxetic honeycombs core, electric field, size parameter, and gradient index) of 2D-FGM layer on the wave velocity of the micro-sandwich beam are evaluated. The results illustrate that the wave velocity which is calculated by the modified couple stress theory increases by about 2.5 times than that in classic theory. Moreover, the phase velocity increases as the geometrical components of auxetic honeycombs core are enhanced.