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Critical speed

About: Critical speed is a research topic. Over the lifetime, 2764 publications have been published within this topic receiving 31365 citations.


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Journal ArticleDOI
TL;DR: In this article, an extensive study has been made of a broad range of polymeric materials, by the instrumented high speed puncture method, and the range of strain rates prevalent in these tests has been related to the strain rates in parts subjected to normal abuse.
Abstract: An extensive study has been made of a broad range of polymeric materials, by the instrumented high speed puncture method. The range of strain rates prevalent in these tests has been related to the strain rates in parts subjected to normal abuse. It has been further demonstrated that at some critical test speed each material exhibited a load maximum which is accompanied by a change in the mode of failure and loss of ductility. This “critical speed” has been shown to be characteristic of the material under test.

11 citations

Journal ArticleDOI
TL;DR: In this article, a fuzzy logic control algorithm is developed and experimentally applied to a rotor test rig, which is suitable to deal with problems of uncertainties and non-linearity, and the experimental results show the ability of the developed fuzzy logic controller to eliminate the oil whip instability when applied to an industrial rotor through an integrated bearing prototype which was designed and manufactured.
Abstract: Oil whip is a self-excited sub-synchronous vibration which limits the range of operating speed of Journal Bearings (JB). JB have wide range of applications due to their high loading capacity, simple geometry, and lubrication. When the speed of rotation increases, the oil whip instability is excited with a frequency corresponding to the rotor critical speed which causes excessive undesirable vibration.A solution for this instability is implemented through this paper. The control action is implemented through a new integrated bearing device. The bearing consists of JB and Electromagnetic Actuator (EMA). The oil whip control action is applied through the EMA.A fuzzy logic control algorithm is developed and experimentally applied to a rotor test rig. The fuzzy logic controller is suitable to deal with problems of uncertainties and non-linearity.The experimental results show the ability of the developed fuzzy logic controller to eliminate the oil whip instability when applied to a test rig which simulates industrial rotor through an integrated bearing prototype which was designed and manufactured.© 2014 ASME

11 citations

Journal ArticleDOI
01 Feb 2018
TL;DR: In this paper, the effect of nonlinearity on vibration of a rotating shaft passing through critical speed excited by nonideal energy source is investigated, where the interaction between a nonlinear gyroscopic continuous system (i.e. rotating shaft) and the energy source was considered.
Abstract: In this paper, the effect of nonlinearity on vibration of a rotating shaft passing through critical speed excited by nonideal energy source is investigated. Here, the interaction between a nonlinear gyroscopic continuous system (i.e. rotating shaft) and the energy source is considered. In the shaft model, the rotary inertia and gyroscopic effects are included, but shear deformation is neglected. The nonlinearity is due to large deflection of the shaft. Firstly, nonlinear equations of motion governing the flexural–flexural–extensional vibrations of the rotating shaft with nonconstant spin are derived by the Hamilton principle. Then, the equations are simplified using stretching assumption. To analyze the nonstationary vibration of the nonideal system, multiple-scale method is directly applied to the equations expressed in complex coordinates. Three analytical expressions that describe variation of amplitude, phase, and angular acceleration during passage through critical speed are derived. It is shown that...

11 citations

Journal ArticleDOI
TL;DR: In this article, it was shown that the critical speed for stability is slower for motion in a circle than for the straight line, which is a common example of a nonholonomic problem of Lagrangian mechanics.

11 citations

Journal ArticleDOI
TL;DR: In this paper, the ride behavior of a coupled vertical-lateral 9 degree of freedom model of a three-wheel vehicle formulated using Lagrangian dynamics is analyzed. But the mathematical model is validated by simulating PSD vertical and lateral acceleration of three-wheeled vehicle sprung mass and comparing the same obtained from actual testing results.
Abstract: This research paper studies the ride behaviour of coupled vertical-lateral 9 degree of freedom model of a three wheel vehicle formulated using Lagrangian dynamics. The mathematical model is validated by simulating PSD vertical and lateral acceleration of three-wheel vehicle sprung mass and comparing the same obtained from actual testing results. The natural frequencies, i.e., eigenvalues of main rigid bodies, i.e., sprung mass, front wheel steering arm and rear unsprung mass of the system are determined through MATLAB simulations. Critical speed of the vehicle is also determined in order to investigate the dynamic stability, and parameters which influence the critical speed are analysed.

11 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20241
202343
2022120
202182
202092
2019102