Surface stress eects on dynamic stability ofdouble-walled boron nitride nanotubes conveyingviscose uid based on nonlocal shell theory

In the present study, the dynamic stability of double-walled boron nitride nanotubes (DWBNNTs) including surface stress eects, is investigated, based on the Gurtin-Murdoch continuum theory. Nonlocal piezoelasticity is incorporated into shell theory to develop a non-classical model for DWBNNT. The eects of van der Waals (vdW) forces, viscose uid passes through the inner nanotube and visco-Pasternak medium are evaluated. Fluid-DWBNNT interaction is evaluated considering the slip boundary condition and bulk viscosity. Hamiltonʹs principle is utilized to derive governing equations with regard to von Karman geometric nonlinearity. Finally, the Incremental Harmonic Balance Method (IHBM) indicates the Dynamic Instability Region (DIR) of DWBNNT. A detailed parametric study is conducted, focusing on the combined eects of the surface parameters, nonlocality, uid velocity, Knudsen number, thermal changes, vdW forces and surrounding medium on the DIR of DWBNNT. Numerical results indicate that considering surface stress eects shifts the DIR to a higher frequency zone.