scholarly journals Non-linear vibro-impact phenomenon belying transmission idle rattle

2008 ◽  
Vol 222 (10) ◽  
pp. 1909-1923 ◽  
Author(s):  
O Tangasawi ◽  
S Theodossiades ◽  
H Rahnejat ◽  
P Kelly
Keyword(s):  
Dynamic Model ◽  
Squeeze Film ◽  
Automotive Transmission ◽  
Lumped Parameter ◽  
Squeeze Film Effect ◽  
Vibration Signature ◽  
Impact Characteristics ◽  
Gear Rattle ◽  
Lubricant Viscosity ◽  
Transmission Gear

This paper investigates automotive transmission gear rattle. Specifically, idle gear rattle, where the repetitive impacts of teeth are subject to light loads is investigated. Hydrodynamic regime of lubrication prevails in lightly loaded impact of teeth pairs. Formation of a lubricant film is due to the combined entraining motion of the lubricant and squeeze film effect. A lumped parameter inertial dynamic model, comprising hydrodynamic impact and flank friction for pairs of simultaneous teeth pairs of loose gears is developed. The overall dynamic model includes seven loose gear pairs and rigid body lateral motions of input and output transmission shafts. Therefore, the influence of fluid film behaviour on idle gear rattle is determined, which has hitherto not attracted sufficient research studies. Gear rattle is manifested by a vibration signature, which corresponds to the bands of frequencies due to torsional engine oscillations, meshing frequencies, and impact characteristics of lubricated conjunctions. The spectral contributions are affected by lubricant rheology, specifically its bulk viscosity variation with temperature. It has been found that spectral disposition tends towards lower frequency contributions with reducing lubricant viscosity because of rising temperatures and lowering lubricant stiffness. The findings conform with the experimental results, also reported in the paper. It has also been shown that squeeze film motion plays a significant role in the propensity of transmission system to rattle.

Dynamics of the Gear Train Set in Wind Turbine

2011 ◽  
Vol 697-698 ◽  
pp. 701-705
Author(s):  
D.D. Ji ◽  
Y.M. Song ◽  
J. Zhang
Keyword(s):  
Wind Turbine ◽  
Dynamic Model ◽  
Harmonic Balance Method ◽  
Planetary Gear ◽  
Gear Train ◽  
Dynamic Responses ◽  
Multi Stage ◽  
Lumped Parameter ◽  
Cartesian Coordinate ◽  
The Impact

A lumped-parameter dynamic model for gear train set in wind turbine is proposed to investigate the dynamics of the speed-increasing gear box. The proposed model is developed in a universal Cartesian coordinate, which includes transversal and torsional deflections of each component, time-varying mesh stiffness, gear profile errors and external excitations. By solving the dynamic model, a modal analysis is performed. The results indicate that the modal properties of the multi-stage gear train in wind turbine are similar to those of a single-stage planetary gear set. A harmonic balance method (HBM) is used to obtain the dynamic responses of the gearing system. The responses give insight into the impact of excitations on the vibrations.

A mixed FEM and lumped-parameter dynamic model for evaluating the modal properties of planetary gearboxes

2018 ◽  
Vol 32 (7) ◽  
pp. 3047-3056 ◽  
Author(s):  
Franco Concli ◽  
Luca Cortese ◽  
Renato Vidoni ◽  
Filippo Nalli ◽  
Giovanni Carabin
Keyword(s):  
Dynamic Model ◽  
Modal Properties ◽  
Mixed Fem ◽  
Lumped Parameter

Signature Analysis of Roller Bearing Vibrations: Lubrication Effects

1992 ◽  
Vol 206 (3) ◽  
pp. 193-202 ◽  
Author(s):  
Y-T Su ◽  
Y-T Sheen ◽  
M-H Lin
Keyword(s):  
Roller Bearing ◽  
Vibration Energy ◽  
Running Speed ◽  
Oil Film ◽  
Spacing Distribution ◽  
Surface Irregularities ◽  
Vibration Signature ◽  
Bearing Assembly ◽  
Bearing Vibration ◽  
Lubricant Viscosity

This study investigates the vibration signature of roller bearings, induced by the surface irregularities of components, under various lubricating conditions. The bearing vibration is modelled as the output of the bearing assembly which is subjected to the excitations of surface irregularities through the oil-film. The oil-film acts as a spring between the roller and race. The stiffness of oil-film under different lubricating conditions is studied from the empirical equation of minimum oil-film thickness. It is shown that the vibration spectra of a normal roller bearing may have a pattern of equal frequency spacing distribution (EFSD) whose frequency information is similar to that of a damaged bearing. Under large loading and low running speed, the vibration energy is low if the lubricant viscosity is high. On the other hand, at high running speed, the vibration energy is high with high lubricant viscosity.

Rod Control Assemblies Wear Mechanisms

2002 ◽  
Author(s):  
Damien Kaczorowski ◽  
Jean-Mary Georges ◽  
Sandrine Bec ◽  
Andre´-Bernard Vannes ◽  
Andre´ Tonck ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Squeeze Film ◽  
Third Body ◽  
Body Effect ◽  
Principal Role ◽  
Squeeze Film Effect ◽  
Steel Surfaces ◽  
Contact Pressures ◽  
Tubular Components

In nuclear power plants, slender tubular components are subjected to vibrations in a PHTW environment. As a result, the two contacting surfaces, tubes and their guides undergo impact at low contact pressures [1]. The components are usually made of stainless steel and it was found that the influence of the PHTW, combined with other actions (such as corrosion, erosion, squeeze film effect, third body effect and cavitation) leads to a particular wear of the material [2] [3]. Therefore, this paper aims to show that the colloidal oxides, formed on the steel surfaces in PHTW, play a principal role in the wear of the surfaces. Actually, due to the specific kinematic conditions of the contact, the flow of compacted oxides abrades the surfaces.

scholarly journals Experimental Evaluation of Squeeze Film Supported Flexible Rotors

1982 ◽  
Author(s):  
M. D. Rabinowitz ◽  
E. J. Hahn
Keyword(s):  
Theoretical Model ◽  
Experimental Evaluation ◽  
Measurement Errors ◽  
Vibration Amplitude ◽  
Squeeze Film ◽  
Experimental Investigations ◽  
Flexible Rotors ◽  
The Mean ◽  
Lubricant Viscosity ◽  
Theory And Experiment

This paper describes the experimental investigations which were conducted to verify existing theoretical vibration amplitude predictions for centrally preloaded, squeeze film supported flexible rotors. The influence of measurement errors and operating condition uncertainties are quantified. The agreement between theory and experiment was excellent, and it is shown that any discrepancy can be explained in terms of errors in determining the mean lubricant viscosity and the orbit magnitudes. Hence, for the range of parameters investigated, the theoretical model and predictions therefrom are validated.

The Effect of Shape and Distribution of Perforations on Squeeze-Film Damping in Parallel Plate Capacitors

2009 ◽  
Author(s):  
Weili Cui ◽  
Ronald N. Miles ◽  
Dorel Homentcovsci
Keyword(s):  
Parallel Plate ◽  
Internal Heat ◽  
Optical Switches ◽  
Squeeze Film ◽  
Mems Devices ◽  
Capacitive Sensing ◽  
Squeeze Film Damping ◽  
Squeeze Film Effect ◽  
Capacitive Mems ◽  
Stationary Plate

The effect of the shape and distribution of perforations in parallel plate capacitive MEMS devices on squeeze-film damping is presented. The squeeze film effect is the most important damping effect on the dynamic behavior of most MEMS devices that employ capacitive sensing and actuation, which typically employ narrow air gaps between planar moving surfaces [1, 2]. The stationary plate of a capacitive device is often perforated to reduce the damping and sensor noise and improve the frequency response. The formula for determining the total viscous damping in the gap contains a coefficient Cp that is associated with the geometry and distribution of the holes on the stationary plate. In this study, the coefficient Cp is determined using the finite element method using ANSYS by analogy with heat conduction in a solid with internal heat generation. Round, elliptical, rectangular, and oval holes that are distributed either aligned or offset are analyzed and compared. It is shown that the surface fraction occupied by the perforations is not the only factor that determines Cp. Both the shape and distribution strongly affect the damping coefficient [3, 4]. By using elongated perforations that are properly distributed, the squeeze film damping could be minimized with the minimum amount of perforation. The analysis performed in this work is quite general being applicable to a very large spectrum of frequencies and to various fluids in capacitive sensors. These results can facilitate the design of mechanical structures that utilize capacitive sensing and actuation, such as accelerometers, optical switches, micro-torsion mirrors, resonators, microphones, etc.

The Effect of Viscosity on Cement Penetration in Total Knee Arthroplasty, an Application of the Squeeze Film Effect

2014 ◽  
Vol 29 (10) ◽  
pp. 2039-2042 ◽  
Author(s):  
Edward J. Silverman ◽  
David C. Landy ◽  
Dustin H. Massel ◽  
David N. Kaimrajh ◽  
Loren L. Latta ◽  
...  
Keyword(s):  
Total Knee Arthroplasty ◽  
Knee Arthroplasty ◽  
Squeeze Film ◽  
Squeeze Film Effect ◽  
Cement Penetration ◽  
Total Knee

Effect of a Circumferential Feeding Groove on the Dynamic Force Response of a Short Squeeze Film Damper

1994 ◽  
Vol 116 (2) ◽  
pp. 369-376 ◽  
Author(s):  
G. L. Arauz ◽  
L. San Andres
Keyword(s):  
Flow Model ◽  
Dynamic Pressure ◽  
Squeeze Film ◽  
Dynamic Force ◽  
Force Response ◽  
Squeeze Film Damper ◽  
Circumferential Groove ◽  
Damping Characteristics ◽  
Radial Forces ◽  
Lubricant Viscosity

The effect of a circumferential feeding groove on the dynamic force response of a short length, open end squeeze film damper is studied experimentally. Damper configurations with increasing groove depths and journal orbit radii were tested for several conditions of whirl frequency and lubricant viscosity. Significant levels of dynamic pressure were measured at the circumferential groove, and relatively large tangential (damping) forces are produced at the groove which contribute considerably to the damping characteristics of the SFD test articles. Radial forces of substantial magnitude are determined at the groove and at the thin film land where the squeeze film Reynolds number is typically less than 1. The circumferential groove is thought to induce an inertia like effect into the film land. The experimental results correlate well with the predictions from a groove volume-circumferential flow model developed.

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