VIBRATION CHARACTERISTICS OF HOLLOW CANTILEVERED BEAMS CONTAINING AN ELECTRORHEOLOGICAL FLUID

Electro-rheological (ER) fluids undergo a phase change when subjected to an external electric field, and this phase change typically manifests itself as a many-order-of-magnitude change in the rheological behavior. This phenomenon permits the global stiffness and energy-dissipation properties of the beam structures to be tuned in order to synthesize the desired vibration characteristics. This paper reports on a proof-of-concept experimental investigation focused on evaluating the vibration properties of hollow cantilevered beams filled with an ER fluid and, consequently, deriving an empirical model for predicting field-dependent vibration characteristics. A hydrous-based ER fluid consisting of corn starch and silicone oil is employed. From the observation of modal characteristics, the beams are considered to be uniform viscoelastic materials and are modeled as a viscously-damped harmonic oscillator. Natural frequency, damping ratio and elastic modulus are evaluated with respect to the electric field and compared among three different beams: two types of different volume fraction of ER fluid and one type of different particle concentration of ER fluid by weight. Transient and forced vibration responses are examined in the time domain to demonstrate the validity of the proposed empirical model.