The analytical model of rheological fluid for vibration and noise control

Abstract

Rheological fluids (RF) also known as controllable viscosity fluids (CVF) introduced in the area of vibration control of mechanical systems, make possible a more efficient control of both transient and continuous vibration. They are used in the design of sound barriers to control noise transmission loss and of diaphragms for the modification of noise absorption characteristics of sound absorbing materials. Their apparent viscosity is controllable by the use of an external (electrical in electro-rheological (ER) or electromagnetic in magneto-rheological (MR) fluids) field. In the absence of an applied external field, the RF exhibits Newtonian-like behavior. An applied external field changes this behavior and the RF shows an additional yield shear stress which depends on strength of this field. In the proposed model the shear stress is expressed as a superposition of two components. One of them is proportional to the viscosity and the relative velocity of the base fluid, the second one depends on the strength of the applied external field. Modification of the external field strength according to selected design parameters (velocity, time, distance or combination) allows the development of a family of vibration or sound attenuating devices which were not achievable before.