Dynamic stability of nanocomposite viscoelastic cylindrical shells coating with a piezomagnetic layer conveying pulsating fluid flow

In this study, the dynamic stability of an embedded viscoelastic composite cylindrical shell reinforced by boron nitride nanotubes (BNNTs) is investigated. The composite cylindrical shell is coated by a viscoelastic piezomagnetic layer and subjected to combined magneto-electro-mechanical loads. The composite polymer matrix and the coating layer are made of polyvinylidene fluoride (PVDF) and iron oxide (CoFe2O4), respectively. The composite cylindrical shell conveys pulsating fluid flows, which results in harmonic oscillations. The equivalent characteristics of composite are determined using micro-electro-mechanical models. Considering the magneto-electro-mechanical coupling, motion equations are obtained using Hamilton's principle. Results show the influences of fluid velocity, geometrical parameters of shell, viscoelastic foundation, orientation angle and percentage of BNNTs on the resonance frequency and stability of a PVDF-coated nanocomposite shell. The result of this study may be used for the design of rotating machines, hydraulic systems and motors.