A COMPARATIVE STUDY OF PARAMETRIC MODELS OF MAGNETORHEOLOGICAL FLUID SUSPENSION DAMPERS
Magnetorheological dampers more commonly called, MR dampers, are being developed for a wide variety of applications where controllable damping is desired. MR damper is an intelligent damper, which is used as automobile suspension for vibration control. MR fluids represent a class of smart materials whose rheological properties change in response to the application of a magnetic field. MR fluid dampers are new type of vibration control elements, having the advantages of rapid damping and stiffness changing in the presence of an applied magnetic field. MR dampers have received a great deal of attention in the last two decades due to their being a potential technology to conduct semi-active control. It is therefore vitally important to understand the dynamic behavior of such devices whose nonlinear hysteresis is a rather complicated phenomenon. Models can accurately represent the behaviour of MR dampers are essential in understanding the operation and working principles of the device. Such models can eliminate a great deal of uncertainties during the design process, which can subsequently enable control strategies for the damper to be developed efficiently and reliably. In this paper, MR fluid structure, damper description and parametric models have been presented.
EFFECT OF FLUID PHYSICAL PROPERTIES ON ROLLOVER STABILITY IN TERMS OF DAMPING OF DYNAMIC FORCES & MOMENTS IN FLUID SLOSHING
Fluid sloshing inside a moving container is often responsible for rollover accidents. In a partially filled container, the liquid moves from side to side resulting in the sloshing phenomena. This can cause the rollover of the container because the sloshing amplifies the forces exerted by the inside fluid on the walls of container. Container's shape, size and fluid properties such as viscosity, density and surface tensions are of paramount importance regarding fluid sloshing. The effect of kinematic viscosity on the damping of dynamic forces and moments, generated as result of fluid sloshing in a moving fuel container, is analyzed in this study. Computational fluid dynamic (CFD) models for different shapes (circular & elliptical) and size of container were developed in CFD GEOM. Different fluid properties were applied and simulations were run in CFD ACE. The increase of kinematic viscosity of the fluid was found to have no effect on peak dynamic forces and moments for each fill level. On the other hand with the increase of density of the fluid the peak dynamic forces and moments increased. Damping factors were calculated for dynamic forces and moments for each fill level and different kinematic viscosities and densities of the fluids. An increasing trend was found in the damping factor for each fill level with the increase of kinematic viscosity and densities of the fluid, but this increase of damping was of insignificant magnitude. It was also found on the basis of peak forces and peak moments generated for the same fill levels that the elliptical containers are suitable for the shipment of fluid material.
Representation of systems disturbed by wide band noise
In this paper, a method of handling and working with wide band noise is developed. We represent wide band noise as a distributed delay of white noise and use it to reduce a nonlinear system disturbed by wide band noise to a nonlinear system disturbed by white noise. An application of this reduction to a nonlinear filtering problem under a wide band noise disturbance is discussed.