Angular wave propagation through one-dimensional phononic crystals made of functionally graded auxetic nanocomposites

Abstract

Composites reinforced with graphene origami nanofillers possess negative Poisson's ratio and obtain multifunctional features offering unique mechanical properties such as tunable auxeticity, high impact resistance, better indentation resistance, and improved fracture toughness. This paper introduces such novel nanocomposites into functionally graded multilayered phononic crystals and numerically investigates the propagation characteristics of normally and obliquely incident waves in the structures containing components with negative Poisson's ratio. Theoretical models of present structures are formulated and solved by the state space approach. The transfer matrix method is used to obtain dispersion relations of normally and obliquely incident waves. A comprehensive parametric study is conducted to discuss the propagation characteristics of elastic waves in the structures with auxetic and non-auxetic components which can be tuned by the weight fraction and hydrogen coverage of graphene origami fillers. The results indicate that introducing components with negative Poisson’ ratio into unit cells can significantly affect wave propagation features. Wave modes have different sensitivities to the weight fraction and hydrogen coverage of graphene origami fillers. Weigh fraction can manipulate all wave modes simultaneously, while hydrogen coverage only influences longitudinal modes and keeps transverse modes nearly undisturbed. Theoretical results shed insights into the design of high-performance multifunctional phononic crystals.