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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 paper, an analytical model has been developed to identify the major variables controlling the generation of impact noise in a wheel/rail system, and the validity of these models has been confirmed by both scale-model and fullscale experiments.

63 citations

Journal ArticleDOI
TL;DR: In this article, the rotordynamics of a double-helical gear transmission system with bearing and gyroscopic effect was investigated using the finite element method, in which Timoshenko beam finite element is used to represent the shaft, a rigid mass for the gear.
Abstract: The rotordynamics of a double-helical gear transmission system is investigated. The equation of motion of the system with bearing and gyroscopic effect is derived by using the finite element method, in which Timoshenko beam finite element is used to represent the shaft, a rigid mass for the gear. Natural frequencies, mode shapes and Campbell diagrams are illustrated to indicate the effects of gear input speed and time varying mesh stiffness. Besides, effects of mesh stiffness on the critical speed of the gear transmission system are analyzed. The numerical results show that the axial force has significant influence on the natural frequency and the mode shape of the double-helical gear transmission system, for which the mix whirling motion dominates the natural characteristics. There are two higher critical speed curves which increase with the mesh stiffness, but one of them is related to the gyroscopic effect.

62 citations

Journal ArticleDOI
15 Apr 2015-Wear
TL;DR: In this paper, a new polymer alloy has been developed by blending powder of UHMWPE and graphite into nitrile rubber for marine stern tube bearings, which has good self-lubrication performance, which decreases the friction coefficient under low speed conditions and the critical speed at which bearing vibration and noise occur.

61 citations

Journal ArticleDOI
TL;DR: In this paper, the influence of critical speed on the free vibration behavior of spinning 3D single-walled carbon nanotubes (SWCNT) is investigated using modified couple stress theory (MCST).
Abstract: In this article, the influences of critical speed on the free vibration behavior of spinning 3D single-walled carbon nanotubes (SWCNT) are investigated using modified couple stress theory (MCST). Moreover, the surrounding elastic medium of SWCNT has been considered as a model of Winkler, characterized by the spring. Taking into consideration the first-order shear deformation theory (FSDT), the rotating SWCNT is modeled and its equations of motion are derived using the Hamilton principle. The formulations include Coriolis, centrifugal and initial hoop tension effects due to rotation of the SWCNT. The accuracy of the presented model is validated by some cases in the literature. The novelty of this study is considering the effects of rotation and MCST, in addition to considering the various boundary conditions of SWCNT. The generalized differential quadrature method (GDQM) is used to discretize the model and to approximate the equation of motion. Then investigation has been made on critical speed and natural frequency of the rotating SWCNT due to the influence of initial hoop tension, material length scale parameter, constant of spring, frequency mode number, angular velocity, length-to-radius ratio, radius-to-thickness ratio and boundary conditions.

61 citations

Journal ArticleDOI
TL;DR: In this paper, a critical sliding speed is found by examining the conditions under which a perturbation in the temperature and stress fields can grow in time and the critical speed corresponds to a condition at which b = 0 and hence at which there is a steady-state solution involuing nonuniform contact pressure.
Abstract: The frictional heat generated during braking causes thermoelastic distortion that modifies the contact pressure distribution. If the sliding speed is sufficiently high, this can lead to frictionalfy excited thermoelastic instability, characterized by major nonuniformi-ties in pressure and temperature. In automotive applications, a particular area of concern is the relation between thermoelasticalfy induced hot spots in the brake disks and noise and vibration in the brake system. The critical sliding speed can be found by examining the conditions under which a perturbation in the temperature and stress fields can grow in time. The growth has exponential character, and subject to certain restrictions, the growth rate b is found to be real. The critical speed then corresponds to a condition at which b = 0 and hence at which there is a steady-state solution involuing nonuniform contact pressure. We first treat the heat sources Q at the contact nodes as given and use standard finite element analysis (FEA) to d...

61 citations


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