scispace - formally typeset
Search or ask a question
Topic

Critical speed

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


Papers
More filters
Journal ArticleDOI
TL;DR: In this article, the problem is recast in terms of the zero-air-speed frequencies, and a simple two-mode solution is proposed based on Reissner's shallowcylindrical-shell vibration theory and piston-theory air forces.
Abstract: The problem is first set up, based on Reissner's shallowcylindrical-shell vibration theory and piston-theory air forces. The nature of the solution and its critical dependence on frequency are illustrated hy a simple two-mode solution. The complexity of the frequency spectrum previously noted by several authors is emphasized in the inability to choose modes of maximum coupling as is commonly done in other aeroelastic problems. Based on these results, the problem is recast in terms of the zeroair-speed frequencies. The solution is then outlined in terms of Gol'denveizer's equations for thin cylindrical shells, including mid-plane inertia, and determination of frequencies and damping of the modes as a function of the aerodynamic parameters. An example is included which illustrates the above difficulties and shows the effect of structural and aerodynamic damping. x, y, z

51 citations

Journal ArticleDOI
TL;DR: In this paper, a traveling structure-traveling load system is modeled as an axially moving string that transports an attached discrete mass between two supports, and the Green's function methods for the two constituent systems, the particle and the uniform traveling string, are combined to derive a Volterra integral equation with delay that governs the interaction force in the coupled system.

50 citations

Proceedings ArticleDOI
26 Dec 2007
TL;DR: In this article, a comprehensive optimization design of PM rotor structure is introduced with multiple constraints, such as deformation, stress and critical speed, and the capacity of enclosure is the optimal goal.
Abstract: Permanent magnet (PM) machine is especially being employed in high speed machines due to its simple structure and high power density. Nowadays, the sintered neodymium-iron-boron (Nd-Fe-B) material is used in most of PM machines. This kind of PM material has large compression strength but small tensile strength, and can not withstand the large centrifugal force due to the high rotation speed. A nonmagnetic steel enclosure is needed to cover the PM material. The tensile press of PM can be reduced by pre-pressure applied to the outer surface of the PM through shrink-fitting into the enclosure. In this paper, the comprehensive optimization design of PM rotor structure is introduced with multiple constraints, such as deformation, stress and critical speed. The capacity of enclosure is the optimal goal. By finite element non-linear contact and optimization analysis, the optimized result for a high speed PM machine with rated speed of 60 000 rpm is presented.

50 citations

Journal ArticleDOI
TL;DR: In this paper, a Jeffcott rotor with a transverse breathing crack is examined, and stability of the system is investigated by Floquet theory considering the crack depth and rotating speed.
Abstract: Transverse breathing cracks have been considered a primary mode of damage in studies of rotordynamic systems In this paper, a Jeffcott rotor with a transverse breathing crack is examined, and stability of the system is investigated by Floquet theory considering the crack depth and rotating speed New breathing functions proposed in a recent publication are adopted to approximate the actual breathing mechanism of the crack Unlike previous studies wherein stability diagrams without detailed information about the stable and unstable regimes of the motion have been provided, in this work we perform a detailed study of the corresponding eigenvalues of the cracked rotor in the complex plane, and the effect of damping on the instability regions has been investigated Our study indicates that the unstable regions appear as the speed of the rotor approaches an integer fraction or an integer multiple of the critical speed of the rotor, whereas bifurcations are detected in certain unstable regimes The results also shows damping has significant influence on the structures of instability regions

50 citations

Journal ArticleDOI
TL;DR: The quantitative analysis of the post-critical performance of bridge decks may deepen the understanding of the wind-resistant performance of bridges and potentially serve as a building block for a more economic wind- resistant design framework for future long-span bridges.

50 citations


Network Information
Related Topics (5)
Torque
80.7K papers, 707.9K citations
67% related
Vibration
80K papers, 849.3K citations
67% related
Plasticity
23.1K papers, 663.6K citations
67% related
Shear stress
35.9K papers, 906.8K citations
67% related
Body movement
14.6K papers, 804.3K citations
66% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20241
202343
2022120
202182
202092
2019102