Non-local wave propagation in embedded armchair TWBNNTs conveying viscous fluid using DQM

In this study, nonlocal electro-thermo-mechanical wave propagation in an embedded armchair three-walled boron nitride nanotube (TWBNNT) conveying viscous fluid under torsional load is investigated. The interaction between two adjacent layers is considered using van der Waals (vdW) forces. The surrounded elastic medium is taken into account using Winkler and Pasternak models. The energy method and Hamilton's principle are used to establish the equations of motion. Given the relationship between the piezoelectric coefficient of armchair boron nitride nanotubes (BNNTs) and stresses, the first-order shear deformation theory (FSDT) is applied to obtain the equations of motion in terms of displacements. The set of coupled governing equations of motion for the TWBNNT are then numerically solved by the differential quadrature method (DQM). The effects of small scale, fluid flow, elastic foundation and temperature on the phase velocity of TWBNNT, critical fluid velocity and critical torsional load are presented graphically. Results show the importance of applying nonlocal elasticity theory on the phase velocity of TWBNNT.