Determination of Coulomb Viscous And Particle Damping Parameters From Harmonically Forced Linear Oscillator

Abstract

Mechanical vibration systems with viscous and Coulomb friction are of importance in the applications of dynamics and control problems. Friction dampers are used in gas turbine engines, high speed turbo pumps, large flexible space structures under carriage of railway bogie, vehicle suspension systems etc. These dampers are used to reduce resonant stresses by providing sliding contact between points experiencing relative motion due to vibration, thereby dissipating resonant vibration energy. Den Hartog first solved the forced response of a SDOF with both viscous and dry friction damping. Hundal studied a base excitation frictional oscillator in which close form analytical solutions of the equation of motion were obtained and results were presented in non-dimensional form as magnification factors versus frequency ratios as functions of viscous and Coulomb friction parameters. Conventional passive damping techniques include viscous fluid damping, eddy current damping, visco-elastic damping, Coulomb friction damping, particle impact damping etc. Particle Vibration Damping (PVD) is a combination of impact damping and friction damping. In a PVD, metal or ceramic particles or powders of small size (0.05 to 5 mm in diameter) are placed inside cavities within or attached to the vibrating structure. Metal particles of high density such as lead or Tungsten give high damping performance due to dissipation of kinetic energy. Particle damping involves the potential energy absorptions and dissipation through momentum exchange between moving particles and vibrating walls, friction impact restitution. The problem of identification of content of each type damping in a given system is a major research area. newlineOutline of proposed work newlineWhen a vibrating system is damped with more than one type of models of damping, it is necessary to determine which of these types of damping are more effective to control the resonant response. In such case, it is important to identify damping parameters from the responses of a vibrating system. Theref