Nonlinear dynamical response of embedded fluid-conveyed micro-tube reinforced by BNNTs

In the present study, nonlinear dynamical behavior and stability of an embedded fluid conveying smart composite micro-tube under imposed electric potential and thermal loadings have been investigated. The composite matrix is the poly-vinylidene fluoride (PVDF) reinforced by double-walled boron nitride nanotubes (DWBNNTs). Composite structure is modeled based on piezoelectric fiber reinforced composite (PFRC) theory and a representative volume element has been considered for predicting the elastic, piezoelectric, dielectric and thermal properties of the smart composite tube. The fluid flow is assumed to be inviscid, irrotational and incompressible. Formulation presented here is based on Euler-Bernoulli beam model with von-Karman geometric nonlinearity and nonlocal elasticity theory. The interactions between smart composite micro-tube and surrounding elastic media are simulated by Pasternak foundation model. The discretized governing equations of motion are directly obtained by minimizing the energy of the system. As a result, the eigen-values and eigenvectors (mode shapes) are to be obtained by the state-space matrix which is then solved by an iterative method to obtain nonlinear frequencies of smart composite tube. The results significantly show that imposing positive electric potential increases nonlinear stability of the system. In addition, it is concluded that applying electric and thermal loadings can be used as well as controlling parameters to improving stability of the smart composite micro-tube. (C) 2012 Elsevier Ltd. All rights reserved.