In this paper, the effectiveness of stiffness and damping of bearing is investigated on the natural frequencies of the rotor-bearing system. The rotor-bearing system consists of a shaft, two bearings and a disk between two bearings. Parallel spring-damper in horizental and vertical directions is considered for modeling the stiffness and damping of bearings. The gyroscopic effect is also conside...

Air-film damping, which dominates over other losses, plays a significant role in the dynamic response of many micro-fabricated devices with a movable mass suspended by various bearing mechanisms. Modeling the damping characteristics accurately will be greatly helpful to the bearing design, control, and test in various micromotor devices. This paper presents the simulated and experimental squeez...

A theoretical investigation into the prediction and measurement of squeeze film stiffness and damping for double hole entry hybrid journal bearings has been undertaken together with a review of previous work to identify critical bearing parameters. The analysis used a partial differentiation of the Poiseuille and Hagen-Poiseuille flow equations to develop a mathematical model for the bearing sq...

Rolling bearing noise has become an aspect of increasing importance for the performance of rotating machinery, like electric motors and gearboxes. Generally, two aspects are important with regard to bearing noise, i.e. the transmission characteristics and the vibration generation characteristics. A potential source of vibrations are for example manufacturing imperfections of the di erent bearin...

Squeeze Film Dampers (SFD) are commonly used for passive vibration control of rotor-bearing systems. The Magnetorheological (MR) and Electrorheological (ER) fluids in SFDs give a varying damping characteristic to the bearing that can provide active control schemes for the rotor-bearing system. A common way to model an MR bearing is implementing the Bingham plastic model. Adding this model to th...

There will be presented a model of a passive magnetic bearing. The model uses the ring with molecular current as a source of external magnetic field (the unmovable magnet mounts in a case of machine). The next ring with molecular current moves in external field generated by unmovable ring (the magnet connects with the shaft of machine). The density of magnetic field is obtained from the Biota-S...

In order to simulate the Stirling engine more easily, the stiffness and damping ratio of the crankshaft bearing are assumed to be steady-state in the research before, but this assumption is contrary to the real condition. Therefore, in this paper, a time-varying stiffness and damping ratio of the crankshaft bearing simulation method has been proposed. Compared with the simulation results of the...

In conventional rotordynamic modeling, hydrodynamic bearings are often characterized by a set of linear stiffness and damping coefficients obtained from a first-order Taylor series expansion of bearing reactions. Theoretically, these coefficients are only valid for small amplitude motion about an equilibrium position. In this paper, a nonlinear dynamic model that overcomes the small amplitude a...

When a piezoelectric transducer is incorporated in a mechanical structure, it is possible to damp the structural vibrations of the base structure by passive energy dissipation in the electrical domain [1]. Due to the strong electromechanical coupling in piezoelectric elements, the mechanical energy can be efficiently converted to electrical energy. By shunting the piezoelectric element to a pas...

A design process comprising aspects of modelling and analysis is developed, implemented and verified for a flexible rotor active magnetic bearing system. The system is specified to experience the first three critical frequencies up to an operating speed of 10,000 rpm. Rotor stability at critical frequencies places specific constraints on the equivalent stiffness and damping parameters of the ac...