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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, the authors investigated the dynamical response of a system consisting of a prestressed covering layer and a half-plane to a moving load applied to the free face of the covering layer.
Abstract: Within the framework of a piecewise homogeneous body model, with the use of the three-dimensional linearized theory of elastic waves in initially stressed bodies, the dynamical response of a system consisting of a prestressed covering layer and a prestressed half-plane to a moving load applied to the free face of the covering layer is investigated. Two types (complete and incomplete) of contact conditions on the interface are considered. The subsonic state is considered, and numerical results for the critical speed of the moving load are presented. The influence of problem parameters on the critical speed is analyzed. In particular, it is established that the prestressing of the covering layer and half-plane increases the critical speed.

10 citations

Journal ArticleDOI
TL;DR: In this paper, the effect of the floating bearing stiffness coefficient on the critical rotational speeds and the shaft dynamic response due to the unbalanced mass were both analyzed using rotor dynamics theory and a finite element analysis.
Abstract: During turbocharger rotor speed-up tests, the sensor installed in the compressor greatly affects the rotor dynamics. The effect of the floating bearing stiffness coefficient on the critical rotational speeds and the shaft dynamic response due to the unbalanced mass were both analyzed using rotor dynamics theory and a finite element analysis. The results illustrate that the initial sensor design reduced the 3rd order critical speed to lower than the maximum normal operating speed which leads to the rubbing and failure of the rotor during the speed-up test. The sensor structure was then optimized to reduce the negative influence of the sensor on the rotor dynamic characteristics to ensure stability during rotor speed-up tests.

10 citations

Journal ArticleDOI
TL;DR: In this article, a small, lightly damped rotor was experimentally tested for a variety of acceleration and deceleration rates, and the amplitude response was plotted as a function of operating speed, with the acceleration rate considered.
Abstract: A small, lightly damped rotor (ζ=0.0088) was experimentally tested for a variety of acceleration and deceleration rates. In each case, the amplitude response was plotted as a function of operating speed, with the acceleration rate considered. In each case the results are compared with theoretical predictions. The results agree within 6% at the peak response. The results of the analysis indicate that for high acceleration rates the critical amplitude response may be reduced by a factor of four or more. The frequency of the effective critical speed may be shifted by up to 20%. Furthermore, a beating frequency was observed in the amplitude data after the rotor had passed through the critical speed. This phenomenon is shown to be the vector sum of a synchronous component of amplitude and a nonsynchronous transient component (at the critical speed). The transient nonsynchronous component is shown explicitly via electronic band-pass filtering, as is the forced response component. Finally, spectral analyses were performed over a range of operating speeds, yielding waterfall diagrams and further verification of the existence of the two components.

10 citations

01 Jan 1988
TL;DR: In this article, the critical speed of the standing wave in the tread band of aircraft bias tires is predicted using the theory of a straight beam on an elastic foundation, under tension.
Abstract: : This report describes the derivation and validation of the critical speed equation that predicts the inceptive speed of the standing wave in the tread band of aircraft bias tires. The critical speed equation is based on the classical theory of a straight beam on an elastic foundation, under tension. Derivations of relations describing each term of the critical speed equation are also presented. These relations describe the effective tire structural properties such as the tread band bending stiffness, the elastic foundation linear spring constant, the belt tension due to inflation pressure, and the tread band effective density. Dynamometer tests of a 49x17/26PR Type VII Goodyear tire was conducted to validate the critical speed equation. Trends relating critical speed with inflation pressure, tread depth, and loaded vertical deflection were correctly predicted, yielding an average of 2.9-percent error. Keywords: Critical speed, Tire dynamics, Aircraft tire, Standing wave, Tire structural properties, Traction wave.

10 citations

Journal Article
TL;DR: In this article, a dynamic model of a single-span blade-rotor-casing coupling system is established based on finite element (FE) method, where the bearing, bladed rotor, discs and casing are simulated using spring-damping element, beam element, shell element and beam element suitable for curved beam separately.
Abstract: Based on finite element (FE) method, a dynamic model of a single span blade-rotor-casing coupling system is established. The bearings, bladed rotor, discs and casing are simulated using spring-damping element, beam element, shell element and beam element suitable for curved beam separately (the casing stiffness and damping using spring-damping element). The blade-casing rub-impact is simulated using point-point contact elements; here the corresponding nodes of the blades and the casing are identified as the contact points. To deal with contact constraint conditions and simulate blade-casing frictional characteristics, the augmented Lagrangian method and the coulomb friction model are adopted, respectively. The responses of the system are analyzed under two loading conditions by using variable-step Newmark-β integral method combined with Newton-Raphson iteration. The results show that the rub-impact at the second critical speed (case 2) is more serious than that at the first critical speed (case 1). 4× (× denotes the rotating frequency) and its edge frequency components, combination frequency components about 1× can be viewed as distinguishable rub-impact features for cases 1 and 2, respectively. Results can provide theoretical basis for rub-impact diagnosis in blade-rotor-casing coupling systems.

10 citations


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