Multiphysics coupled thermal-fluid-structure behavior of piezoelectric honeycomb sandwich microplates

This study examines the vibrational behavior of closed-circuit piezoelectric sandwich microplates with hexagonal honeycomb cores, fully immersed in a fluid and subjected to nonlinear thermal gradients. To capture the size-dependent behavior at the microscale, the modified strain gradient theory (MSGT) is employed alongside the first-order shear deformation theory (FSDT). The honeycomb core is modeled as an orthotropic material, with its properties determined using a modified form of Gibson’s equation. To provide an accurate depiction of fluid–structure interaction, the surrounding fluid is idealized as incompressible, inviscid, and irrotational. The velocity potential of the fluid is derived from the governing boundary conditions, facilitating the computation of added mass effects on the microplate. By using Hamilton’s principle, the electromechanical governing equations of the system are developed, taking into account the interaction between the thermal, piezoelectric, and structural responses. A detailed parametric analysis investigates the effects of plate geometry, length-scale dependency, thermal gradients, honeycomb core characteristics, fluid density, and fluid depth on the system’s natural frequencies.