Flow induced vibrations of microcantilevers

Abstract

This thesis is focused on the study of flow-induced vibrations of microcantilevers. A flow chamber for testing microcantilevers under different flow rates is designed and constructed. Several cantilevers of different linear dimensions and resonant fre- quencies are subsequently exposed to turbulent air flow. The resulting vibrations are measured using an optical lever technique. The time traces of the vibrations are recorded as a function of flow rate. This vibration data are subsequently analyzed in frequency and time domains. It is found that the vibrations begin at Reynolds numbers (in cantilever dimensions) substantially lower than those expected for classi- cal vortex-induced vibrations. The flow induced vibration frequencies depend wealdy on the flow rates; the amplitudes increase strongly with increasing flow rates. Given that the flow in the flow chamber is turbulent, it is proposed that the vibrations result from an interaction of the resonant body with the turbulent flow. Further experiments are proposed to confirm or refute this hypothesis of turbulence-driven vibrations of microcantilevers.