Modal characteristics of a cantilever beam with the free-end immersed in a magnetorheological fluid

Abstract

This paper presents modal characteristics of a flexible cantilever beam with its free-end immersed in a magnetorheological (MR) fluid. Immersing the beam in MR fluid allows to change boundary conditions of the free-end by controlling the magnetic field intensity across MR fluid. Hence, the modal characteristics of the beam, such as natural frequency are varied as a function of the magnetic field applied to MR fluid domain. First, a thin cantilever beam was manufactured according to a design comprising a macro fiber composite (MFC) actuator for the beam excitation. Then, the dynamic responses of the beam were measured under two conditions: the free-end vibrating in air and the free-end immersed in MR fluid with different magnetic field intensities. The changes in the dynamic characteristics, such as resonance frequency, damping ratio, and resonant amplitude were evaluated and compared for various conditions. A significant reduction in the natural frequency was observed when the free-end of the beam was immersed in MR fluid and changed further when coil current was applied. In addition, the multiphysics simulation of the system was performed using finite element method. The numerical results of the dynamic response of the system showed good agreement with experimental results.