Cancelation of acoustic scattering from a smart hybrid ERF/PZT-based double‐wall composite spherical shell structure

Abstract

A coupled multiphysics vibroacoustic model is developed for axisymmetric scattering of plane progressive time-harmonic sound waves from a fluid-filled and submerged smart hybrid double concentric composite spherical shell that incorporates noncollocated piezoelectric (PZT) and electrorheological fluid (ERF) actuator layers. The dynamic equations of motion for the PZT- and ERF-based sandwich shells are independently derived using Hamilton’s variational principle, Kirchhoff-Love thin shell formulation, Maxwell's electrodynamics equations, and Kelvin-Voigt viscoelastic constitutive model. The frequency-domain multi-input/multi-output (MIMO) sliding mode control (SMC) strategy is then applied to activate the sound scattering cancelation capability of the triply-coupled smart structure through collaborative active/semi-active operation of the built-in actuator elements. Extensive numerical simulations reveal the remarkable broadband attenuation of both types of wide and narrow resonance peaks arising in the calculated far-field backscattering spectra that are primarily linked to various types of interacting fluid- and shell-borne peripheral waves. Also, the near-field effectiveness and cloaking potentials of proposed smart hybrid design in realizing partial or complete acoustic invisibility with respect to the incident sound field are explored at selected frequencies. In particular, the superior 3 D acoustic cloaking capabilities of the PZT/ERF and ERF/ERF configurations are established noting the low actuation energy advantage of the ERF element.