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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.


Papers
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01 Jan 2007
TL;DR: The paper reviews the criteria for nonlinear assessment of vehicle stability based on the simulation of vehicle response to random track irregularity, showing the need for more objective criteria than the ones based on physical testing for vehicle homologation.
Abstract: Considering the specific case of a concentrated power locomotive with motors mounted on the bogie frame, the paper reviews the criteria for nonlinear assessment of vehicle stability based on the simulation of vehicle response to random track irregularity, showing the need for more objective criteria than the ones based on physical testing for vehicle homologation. The effect of elastic motor connection on the bogie frame is examined by linear and nonlinear calculations, which shows that stiffness and damping properties of motor connection have a strong influence on vehicle stability.

31 citations

Patent
13 Mar 2008
TL;DR: In this article, a control method and apparatus for critical rotational speed avoidance in a compressor-expander set in a gas refrigeration system is presented, where an antisurge valve for a recycle compressor is opened upon a trip or shutdown of one compressor.
Abstract: A control method and apparatus for critical rotational speed avoidance in a compressor-expander set in a gas refrigeration system. By varying an opening of an antisurge or recycle valve, a shaft power used by the compressor in the compressor-expander set may be varied, thereby varying the rotational speed of the compressor-expander set to move it away from its critical speed zone. Additionally, a feedforward signal may be provided by a compressor-expander set control system to cause an antisurge valve for a recycle compressor to open upon a trip or shutdown of one compressor-expander set.

31 citations

Journal ArticleDOI
TL;DR: In this article, the effects of bearing support flexibility on rotor stability and unbalance response were investigated using a flexible rotor supported by fluid film bearings on flexible supports with fifteen support configurations.
Abstract: An experimental study of the effects of bearing support flexibility on rotor stability and unbalance response is presented. A flexible rotor supported by fluid film bearings on flexible supports was used with fifteen support configurations. The horizontal support stiffness was varied systematically while the vertical stiffness was kept constant. The support characteristics were determined experimentally by measuring the frequency response functions of the support structure at the bearing locations. These frequency response functions were used to calculate polynomial transfer functions that represented the support structure. Stability predictions were compared with measured stability thresholds. The predicted stability thresholds agree with the experimental data within a confidence bound for the logarithmic decrement of ±0.01. For unbalance response, the second critical speed of the rotor varied from 3690 rpm to 5200 rpm, depending on the support configuration. The predicted first critical speeds agree with the experimental data within -1.7 percent. The predicted second critical speeds agree with the experimental data within 3.4 percent. Predictions for the rotor on rigid supports are included for comparison.

31 citations

Journal ArticleDOI
TL;DR: In this paper, a criterion guaranteeing asymptotic stability of non-conservative, linear gyroscopic systems is derived, which applies to linear systems with internal damping, external damping and circulatory forces as well as systems with negative definite stiffness matrix.

31 citations

Journal ArticleDOI
TL;DR: The findings enable a comprehensive understanding of friction characteristics for several classes of two-dimensional materials, which is important to elucidate the feasibility of using these materials as protective and solid-lubricant coating layers for nanoscale devices.

31 citations


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