Tradespace Exploration of Geometry for a Spacesuit Hip Bearing Assembly

2020 ◽  
Author(s):  
Patrick McKeen ◽  
Leia Stirling
Keyword(s):  
Bearing Assembly ◽  
Tradespace Exploration

The importance of bearing stiffness and load when estimating the size of a defect in a rolling element bearing

2018 ◽  
Vol 18 (5-6) ◽  
pp. 1527-1542 ◽  
Author(s):  
Francesco Larizza ◽  
Alireza Moazen-Ahmadi ◽  
Carl Q Howard ◽  
Steven Grainger
Keyword(s):  
Large Data ◽  
Rolling Element Bearing ◽  
Static Stiffness ◽  
Data Set ◽  
Rolling Element ◽  
Bearing Stiffness ◽  
Bearing Assembly ◽  
Element Bearing ◽  
Vibration Signatures ◽  
Force Displacement

The change in the static stiffness of a bearing assembly is an important discriminator when determining the size of a defect in a rolling element bearing. In this article, the force–displacement relationships for defective bearings under various static radial loadings at various cage angular positions are analytically estimated and experimentally measured and analyzed. The study shows that the applied load has a significant effect on the static stiffness variations in defective rolling element bearings. The experimental measurements of the effect of the defect size on the varying stiffness of the bearing assembly, which has not been shown previously, provides valuable knowledge for developing methods to distinguish between defective bearings with defects that are smaller or larger than one angular ball spacing. The methods and results presented here contribute to the wider experimental investigation of the effects of loadings on the varying static stiffness of defective bearings and its effects on the measured vibration signatures. A large data set was obtained and has been made publicly available.

Introducing Cost Models to Conceptual Tradespace Exploration

2018 ◽  
Vol 28 (1) ◽  
pp. 16-29 ◽  
Author(s):  
E. Alex Baylot ◽  
Drew Kelley ◽  
James Richards ◽  
Deanna Hardin
Keyword(s):  
Cost Models ◽  
Tradespace Exploration

A Test Facility for the Measurement of Torques at the Shaft to Seal Interface in Brush Seals

1999 ◽  
Vol 121 (1) ◽  
pp. 160-166 ◽  
Author(s):  
P. E. Wood ◽  
T. V. Jones
Keyword(s):  
Contact Pressure ◽  
Indirect Measurement ◽  
Test Facility ◽  
Axial Loads ◽  
Rotating Shaft ◽  
Brush Seal ◽  
Wide Range ◽  
Bearing Assembly ◽  
Brush Seals ◽  
Wide Speed Range

An important factor in the performance of brush seals for a wide range of gas turbine applications is the rate of wear at the seal to shaft interface, which is dependent on the contact pressure that exists between the bristles and rubbing surface. This is dependent on a variety of effects. Principally, these are the aerodynamic forces bending the bristles onto the rubbing surface, frictional effects within the bristle pack and at the backing ring that arise with the application of pressure differential, geometrical changes due to centrifugal and thermal growths, and transient differential movements of the rotor that develop in flight manoeuvres. In order to investigate the effect of these phenomena on contact pressure, a test facility has been devised in which the torque exerted by a brush seal on a rotating shaft is used as an indirect measurement of contact pressure. This has necessitated the design of a test facility in which all system torques can be fully calibrated. Consequently, a pressure balanced design has been adopted in which applied seal differential and pressure levels have a minimal effect on axial loads at the rotor bearing assembly. The primary method of torque measurement is the instantaneous deceleration of the rotor. Thus, measurements over a wide speed range are acquired with high frequency instrumentation. The means whereby small parasitic torques are evaluated and corrected is given. Results demonstrating the dependence of contact pressure on seal differential and pressure levels are presented.

Design and Analysis of Main Bearing Assembly for Thermal Power Plant's Ventilation Equipment

2013 ◽  
Vol 1 (1) ◽  
pp. 129-138
Author(s):  
Hyeong-Ryong Ryu ◽  
In-Ho Cho ◽  
Seong-Gwan Kim ◽  
Seong-Il Jeon ◽  
Young-Sik Pyoun
Keyword(s):  
Thermal Power ◽  
Main Bearing ◽  
Bearing Assembly

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.

Traction Characteristics of a Rolling Element Bearing Under Rapid Acceleration and Implications for Auxiliary Operation in Magnetic Bearing Systems

2006 ◽  
Author(s):  
Matthew O. T. Cole ◽  
Theeraphong Wongratanaphisan
Keyword(s):  
Dynamic Behavior ◽  
Magnetic Bearing ◽  
Rolling Element Bearing ◽  
Elastic Behavior ◽  
Friction Forces ◽  
Auxiliary Operation ◽  
Rolling Element ◽  
Rolling Elements ◽  
Auxiliary Bearing ◽  
Bearing Assembly

The application of rolling element bearings for auxiliary operation in magnetic bearing systems is quite common, yet such operation is very different to that for which standard bearings are designed. During initial touchdown of a spinning rotor with an auxiliary bearing, rapid acceleration of the bearing inner race results in large inertial and friction forces acting on the rolling elements. Complex dynamic behavior of the bearing assembly and resulting traction forces are difficult to predict but, nonetheless, have important implications for both rotor dynamic behavior and thermo-elastic behavior of the bearing components. The aim of this work is to obtain an insight into bearing behavior by analyzing component interaction forces that would arise based on the assumption that the overall bearing traction torque is dependent only on instantaneous load, speed and acceleration. How such an analysis can be verified by experimental measurements of traction during rapid acceleration is discussed and some initial experimental results are presented. The implications for modeling and prediction of rotor-magnetic bearing system behavior during touchdown are also discussed.

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