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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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TL;DR: Batchelor et al. as discussed by the authors studied the relationship between the angular velocity of the inner cylinder and the torque transmitted by fluid friction to an outer cylinder and found that the torque has the functional form where a and b are constants determined from the data.
Abstract: An empirical relationship for the torque transmitted by fluid friction to an outer cylinder as a function of the angular velocity of the inner cylinder has been obtained by analysis of experimental data published by Wendt, Taylor and Donnelly. With one exception it is found that the torque G has the functional form where Ω1 is the angular velocity of the inner cylinder and a and b are constants determined from the data. The formula applies to a range of values of Ω1 above the onset of instability extending to about 10 times the critical angular velocity. The experiments also show that the finite amplitude analysis recently advanced by Stuart gives the correct variation of torque over a short range above the critical speed. At speeds well beyond critical it is found that G varies approximately as Ω1.51, and that the variation of torque with gap width can be expressed as a simple power law with exponent about 0.31. In an appendix Dr G. K. Batchelor shows that these latter relations are consistent with the supposition that the flow is steady and consists of inviscid cores surrounded by boundary layers.

125 citations

Journal ArticleDOI
TL;DR: In this paper, the Coulomb's law was used to analyze the response of a single-degree-of-freedom system with dry friction under a constant velocity of the base and/or harmonic driving force.

123 citations

Journal ArticleDOI
TL;DR: In this article, an Euler-Bernoulli beam under the excitation of moving mass is considered and the dynamics of the uncontrolled system is governed by a linear, self-adjoint partial differential equation.

118 citations

Journal ArticleDOI
TL;DR: In this paper, a method for determining the critical sliding speed of axisymmetric clutches or brake is presented. Butler et al. developed a linear eigenvalue problem on the two-dimensional cross-sectional domain for the exponential growth rate for each Fourier finite element.
Abstract: A › nite-element method is developed for determining the critical sliding speed for thermoelastic instability of an axisymmetric clutch or brake. Linear perturbations on the constant-speed solution are sought that vary sinusoidally in the circumferential direction and grow exponentially in time. These factors cancel in the governing thermoelastic and heat-conduction equations, leading to a linear eigenvalue problem on the two-dimensional cross-sectional domain for the exponential growth rate for each Fourier wavenumber. The imaginary part of this growth rate corresponds to a migration of the perturbation in the circumferential direction. The algorithm is tested against an analytical solution for a layer sliding between two half-planes and gives excellent agreement, for both the critical speed and the migration speed. Criteria are developed to determine the mesh re› nement required to give an adequate discrete description of the thermal boundary layer adjacent to the sliding interface. The method is then used to determine the unstable mode and critical speed in geometries approximating current multi-disc clutch practice.

118 citations

Journal ArticleDOI
TL;DR: In this article, the effects of various parameters influencing the dynamic response of railway bridges are investigated and a versatile and computationally efficient numerical model was developed for this purpose, which incorporates three-dimensional multi-body train and finite element bridge subsystems.

118 citations


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