In order to address the problems of insufficient load capacity and rotor vibration, an active fluid-film bearing lubricated with magnetorheological fluid (MRF) is proposed. First, geometry MRF designed its intelligent lubrication mechanism analyzed clarify advantages. addition, mathematical model bearing-rotor system derived, FEM utilized obtain stiffness damping coefficients supplement model. ...

This work presents a technique that allows the calibration of mathematical models in rotating systems. The method is based on the application of a hybrid meta-heuristic search, which employs genetic algorithm and simulated annealing. The capabilities of the method are evaluated by means of experimental results obtained in the test-rig of Politecnico di Milano. The experimental set up consists o...

This paper presents a mathematical model to investigate the nonlinear dynamic behavior of a high speed rotor-bearing system due to defects of rolling elements. Two defects have been considered for the study, one defect as off-sized rolling elements and other defect as rolling element waviness. In the formulation, the contacts between rolling elements and inner/outer races are considered as nonl...

The dynamic behaviour of a high speed balanced rotor supported on deep groove ball bearings (SKF-6205) has been studied by numerically simulated results. Since, internal radial clearance (IRC) is inevitably present in all class and types of bearing, in this paper it (IRC-C3) is considered as main source of nonlinearity with speed as control parameter. The complex mathematical model simulates no...

The Gilbert damping of ferromagnetic materials is arguably the most important but least understood phenomenological parameter that dictates real-time magnetization dynamics. Understanding the physical origin of the Gilbert damping is highly relevant to developing future fast switching spintronics devices such as magnetic sensors and magnetic random access memory. Here, we report an experimental...

In the present paper the behavior of an elastically mounted cylinder in low and high mass-damping ratio is investigated. For high mass-damping ratio, a classical wake oscillator model is used. At the first, by neglecting all damping and nonlinear terms of this model, the possibility of using a linear model for determination of the lock-in range and the dominant mode is investigated. Then, w...

Different expressions have been developed to determine damping of structures based on various hysteretic models and ductility levels. Since Slenderness ratio is an important parameter on the hysteretic behavior of special concentrically- braced frames (SCBF), in this paper new expressions for determination of damping of such frames are developed based on slenderness ratio and ductility. Two typ...

In tribology, the Rayleigh step bearing has maximum load capacity of any feasible geometry. Traditional tribology resources have demonstrated that an ideal geometry which maximizes capacity. Both in nature and technology, rough textured surfaces are essential for lubrication. While surface roughness enhances performance bearings as efficiency measure, it still a significant impact on load-carry...

A comprehensive approach to the design of UPFC controllers (power-flow controller, DC-voltage regulator and damping controller) is presented. Studies reveal that damping is adversely affected by the incorporation of a DC-voltage regulator. Investigations were carried out to understand the relative effectiveness of modulation of thc UPFC control signals inR, SB, niE and <5£ on damping of the sys...

Self-excited vibration of the tool, regenerative chatter, can be predicted and eliminated if the stability lobe diagram of the spindle–holder–tool assembly is known. Regardless of the approach being used, analytically or numerically, forming the stability lobe diagram of an assembly implies knowing the point frequency response function (FRF) in receptance form at the tool tip. In this paper, it...