Flutter and bifurcation instability analysis of fluid-conveying micro-pipes sandwiched by magnetostrictive smart layers under thermal and magnetic field

Fluid-conveying micro/Nano structures are key tools in MEMS and NEMS applications especially for drug delivery systems to attack a specific tumor like cancer cells. Vibrational characteristics of such tools play a crucial role in delivering efficient and reliable performance in various applications. As a result, vibration and instability control of such systems is of great importance. Vibration and instability response of magnetostrictive sandwich cantilever fluid-conveying micro-pipes is investigated in this paper utilizing smart magnetostrictive layers as actuators. Euler–Bernoulli beam model together with modified couple stress theory (MCST) are used to model the problem. As main properties of these smart layers, magnetic intensity effect, velocity feedback gain and thermal effects are taken into account in the modeling. The governing equation is extracted employing Hamilton’s principle. Extended Galerkin procedure is applied to discretize the governing equation and obtain the eigenvalue problem which is solved straightforwardly to reach the eigenvalues. Afterwards, eigenvalue diagrams are studied to analyze the vibrational characteristics and possible instabilities (flutter and bifurcation) occurring in first three modes of the system. Throughout this analysis, the role of various intrinsic properties of the magnetostrictive layers on the critical flow velocity and frequency is studied in detail. The numerical results show a good ability for the used smart layers to control the instability of fluid-conveying micro-pipes. Therefore, these sandwich structures may be helpful for achieving a novel design for such systems.