Microfluid-induced nonlinear free vibration of microtubes

The microfluid-induced nonlinear free vibration of microtubes is studied in this paper. A derivation of the nonlinear equation of motion is presented based on Hamilton's principle and a modified couple stress theory. The geometric nonlinearity, arising from the midplane stretching, is taken into account. The modified couple stress theory is used to capture the micro-structure dependent size effects when the microtubes are at micron- and submicron scales. The static postbuckling problem is then studied and the size-dependent postbuckling configurations are analyzed. The approximate solution to the nonlinear free vibration is obtained using the homotopy analysis method. The influences of internal material length scale parameter, outer diameter, flow velocity, and Poisson's ratio on the dynamic behavior are discussed in detail. (C) 2013 Elsevier Ltd. All rights reserved.