Research Papers: Applications

A New Approach to Modeling Surface Defects in Bearing Dynamics Simulations

[+] Author and Article Information
Ankur Ashtekar, Farshid Sadeghi

School of Mechanical Engineering, Purdue University, West Lafayette, IN 47906

Lars-Erik Stacke

 SKF Engineering Research Centre, MDC RKS-2, 41550 Göteborg, Sweden

J. Tribol 130(4), 041103 (Aug 12, 2008) (8 pages) doi:10.1115/1.2959106 History: Received December 22, 2007; Revised April 30, 2008; Published August 12, 2008

A dynamic model for deep groove and angular contact ball bearings was developed to investigate the influence of race defects on the motions of bearing components (i.e., inner and outer races, cage, and balls). In order to determine the effects of dents on the bearing dynamics, a model was developed to determine the force-deflection relationship between an ellipsoid and a dented semi-infinite domain. The force-deflection relationship for dented surfaces was then incorporated in the bearing dynamic model by replacing the well-known Hertzian force-deflection relationship whenever a ball/dent interaction occurs. In this investigation, all bearing components have six degrees-of-freedom. Newton’s laws are used to determine the motions of all bearing elements, and an explicit fourth-order Runge–Kutta algorithm with a variable or constant step size was used to integrate the equations of motion. A model was used to study the effect of dent size, dent location, and inner race speed on bearing components. The results indicate that surface defects and irregularities like dent have a severe effect on bearing motion and forces. Furthermore, these effects are even more severe for high-speed applications. The results also demonstrate that a single dent can affect the forces and motion throughout the entire bearing and on all bearing components. However, the location of the dent dictates the magnitude of its influence on each bearing component.

Copyright © 2008 by American Society of Mechanical Engineers
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Figure 8

Unit contact force vector schematics: (a) Case I; (b) Case II

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Figure 9

Dent location on outer race

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Figure 10

Contact force (N, radial axis) between ball-race at angle(deg) about bearing axis: (a) DBM without dent; (b) DBM with dent

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Figure 11

Inner race center of mass motion

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Figure 12

Contact force between ball-cage: (a) DBM without dent; (b) DBM with dent

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Figure 13

Contact force (N, radial axis) between ball-race at angle (deg) about bearing axis for various dent sizes; (a) DBM with small dent; (b) DBM with large dent

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Figure 14

Contact force (N, radial axis) between ball-race at angle (deg) about bearing axis for various IR speed is: (a) IR speed of 1000rpm; (b) IR speed of 10,000rpm

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Figure 15

Contact force between ball-cage for various dent locations: (a) dent offset by 2deg from centerline; (b) dent offset by 10deg from centerline

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Figure 16

Contact force (N, radial axis) between ball-race at angle (deg) about bearing axis for various IR speed is: (a) dent cluster (b) DBM with cluster at 135deg

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Figure 2

Example Hertzian contact profiles: (a) circular contact area; (b) elliptical contact area

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Figure 3

Pressure profile for a dented contact: (a) pressure profile; (b) section along Y=0.0

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Figure 4

Pressure profile for a shallow dented contact

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Figure 5

Variation of exponent nmax with dimensionless load, ellipticity, dent depth, and diameter: (a) effect of load and ellipticity; (b) effect of dent depth and diameter

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Figure 6

Variation of n over dented area

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Figure 7

Offset distance ε between the dent center and ball center



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