Vibration Analysis of Fluid-Loaded Sandwich Microshells with Fluid-permeated High-performance Porous Core and Piezoelectric Face Sheets Coatings on Spatially Varying Elastic Substrates

This study presents a comprehensive vibration analysis of fluid-loaded sandwich microshells, featuring fluid-permeated high-performance porous cores and piezoelectric face sheet coatings supported on spatially varying Winkler–Pasternak elastic substrates. A fluid-saturated porous core with adjustable fluid permeation qualities is positioned between two piezoelectric face sheets in the sandwich microshell arrangement. The porous core demonstrates outstanding performance features. The impact of fluid saturation in the porous core is examined by the Skempton coefficient, which measures the correlation between pore pressure and applied stress in the fluid-saturated medium. The velocity potential function technique is used to explain the irrotational flow characteristics, and the fluid motion is controlled by the assumption of perfect fluid behavior. To account for size-dependent effects present in microstructures, the analytical framework combines modified strain gradient theory (MSGT) with first-order shear deformation theory (FSDT). Analytical solutions are obtained by applying Fourier series expansions to the governing equations of motion, which are derived from Hamilton’s principle. Extensive parametric studies show that the factors that significantly affect frequency fluctuations include the liquid level, applied electric voltage, MSGT length scale parameters, elastic medium characteristics, imperfection type and Skempton coefficient.