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 nitridenanotubes (dwbnnts) including surface stress eects, is investigated, based on thegurtin-murdoch continuum theory. nonlocal piezoelasticity is incorporated into shelltheory 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 mediumare evaluated. fluid-dwbnnt interaction is evaluated considering the slip boundarycondition and bulk viscosity. hamilton's principle is utilized to derive governing equationswith regard to von karman geometric nonlinearity. finally, the incremental harmonicbalance method (ihbm) indicates the dynamic instability region (dir) of dwbnnt.a detailed parametric study is conducted, focusing on the combined eects of the surfaceparameters, nonlocality, uid velocity, knudsen number, thermal changes, vdw forces andsurrounding medium on the dir of dwbnnt. numerical results indicate that consideringsurface stress eects shifts the dir to a higher frequency zone.