scholarly journals Effect of Various Defects in Roller Bearings and Ball Bearings on Vibration

2019 ◽  
Vol 8 (12) ◽  
pp. 5137-5141
Keyword(s):  
Ball Bearing ◽  
Surface Defects ◽  
Roller Bearing ◽  
Vibration Response ◽  
Maintenance Cost ◽  
Artificial Defect ◽  
Outer Race ◽  
Vibration Signature ◽  
Inner Race ◽  
Load Conditions

The bearing is very important segment in any rotating machinery. It is continually running under changing speed and load conditions. Failure of bearing frequently results in extensive mechanical downtime that has monetary outcomes. Timely diagnosis of bearing breakdown is to avoid machines failure, as well as to decrease the maintenance cost of machine. To analyze failure of the bearing artificial defect were created on various elements of the bearing and using vibration signature for monitoring its condition analysis is carried.In this paper the effect of various surface defects on the vibration response of outer race and inner race of the ball bearing and Roller bearing is discussed. Vibration spectrum produced by bearing with defect on inner or outer race under different load conditions is taken and effect of defect size and load on the vibration response has been investigated. Results are presented in time and frequency domain. The results obtained by experimentations are compared with MATLAB results

Chaotic dynamics of cylindrical roller bearing supported by unbalanced rotor due to localized defects

2020 ◽  
Vol 26 (21-22) ◽  
pp. 1898-1908
Author(s):  
Pravajyoti Patra ◽  
V Huzur Saran ◽  
Suraj P Harsha
Keyword(s):  
High Speed ◽  
Nonlinear Differential Equations ◽  
Roller Bearing ◽  
Major Elements ◽  
Mass Model ◽  
Outer Race ◽  
Vibration Signature ◽  
Discrete Spectra ◽  
Cylindrical Roller ◽  
Inner Race

This article presents a nonlinear vibration signature study of high-speed defective cylindrical roller bearings under unbalance rotor conditions. Qualitative analysis is conducted considering a spall defect of a specific size on major elements such as outer race, inner race, and rollers. A spring-mass model with nonlinear stiffness and damping is formulated to study the dynamic behavior of the rotor-bearing model. The set of nonlinear differential equations are solved using the fourth-order Runge–Kutta method to predict the characteristics of the discrete spectra and analyze the stability of the system. The results show that higher impulsive forces are generated because of outer race defects than defects in the inner race and roller. This can be explained as every time the roller passes through the defect in the outer race during rotation, the energy is released. However, in the case of both the roller and inner race defects, the impulsive force generated in the load zone is averaged because of the force generated in the unloading zone. The route to chaos from periodic to quasiperiodic response has been observed and analyzed that vibration signature is very much sensitive not only to the defects of bearing components but also to the rotor speed.

Motions of an Unstable Retainer in an Instrument Ball Bearing

1994 ◽  
Vol 116 (2) ◽  
pp. 202-208 ◽  
Author(s):  
E. Kingsbury ◽  
R. Walker
Keyword(s):  
Experimental Investigation ◽  
Rigid Body ◽  
Rotation Rate ◽  
High Frequency ◽  
Ball Bearing ◽  
Stable Operation ◽  
Frequency Content ◽  
Outer Race ◽  
Group Rotation ◽  
Inner Race

We made an experimental investigation of the motions of the retainer in an instrument ball bearing during stable operation and during squeal. Radial motions of the retainer were measured with two fiber-light probes mounted 90 physical degrees apart. A signal analyzer was used to determine the phasing and frequency content of the probe signals. During squeal, a high-frequency retainer motion was found to be superimposed on the normal retainer ball group rotation rate. This high-frequency motion, which we call whirl, is a rigid-body translation in a circle. Whirl direction is opposite to the race for outer-race rotation, but in the same direction for inner-race rotation. Whirl frequency is approximately proportional to ball spin rate. The observations agree with predictions made from a squeal model based on retainer-to-ball frictional coupling that was originally presented in 1965.

scholarly journals A Computational Fluid Dynamics Simulation of Oil–Air Flow Between the Cage and Inner Race of an Aero-engine Bearing

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Akinola A. Adeniyi ◽  
Hervé Morvan ◽  
Kathy Simmons
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Ball Bearing ◽  
Flow Behavior ◽  
Dynamics Simulation ◽  
Shaft Speed ◽  
Outer Race ◽  
Fine Mesh ◽  
Entry Points ◽  
Inner Race

In aero-engines, the shafts are supported on bearings that carry the radial and axial loads. A ball bearing is made up of an inner race, an outer race, and a cage, which contains the balls, these together comprise the bearing elements. The bearings require oil for lubrication and cooling. The design of the bearing studied in this work is such that the oil is fed to the bearing through holes/slots in the inner race. At each axial feed location, the oil is fed through a number of equispaced feedholes/slots but there are a different number of holes at each location. Once the oil has passed through the bearing, it sheds outward from both sides into compartments known as the bearing chambers. A number of studies have been carried out on the dynamics of bearings. Most of the analyses consider the contributions of fluid forces as small relative to the interaction of the bearing elements. One of the most sophisticated models for a cage–raceway analysis is based on the work of Ashmore et al. (2003, “Hydrodynamic Support and Dynamic Response for an Inner-Piloted Bearing Cage,” Proc. Inst. Mech. Eng. Part G, 217, pp. 19–28], where the cage–raceway is considered to be a short journal bearing divided into sectors by the oil feeds. It is further assumed that the oil exits from the holes and forms a continuous block of oil that exits outward on both sides of the cage–raceway. In the model, the Reynolds equation is used to estimate the oil dynamics. Of interest in this current work is the behavior of the oil and air within the space bounded by the cage and inner race. The aim is to determine whether oil feed to the bearing can be modeled as coming from a continuous slot or if the discrete entry points must be modeled. A volume of fluid (VOF) computational fluid dynamics (CFD) approach is applied. A sector of a ball bearing is modeled with a fine mesh, and the detailed simulations show the flow behavior for different oil splits to the three feed locations of the bearing, thus providing information useful to understanding oil shedding into the bearing chambers. This work shows that different flow behaviors are predicted by models where the oil inlets through a continuous slot are compared to discrete entry holes. The form and speed of oil shedding from the bearing are found to depend strongly on shaft speed with the shedding speed being slightly higher than the cage linear speed. The break-up pattern of oil on the cage inner surface suggests that smaller droplets will be shed at higher shaft speed.

A Multiphase Computational Study of Oil-Air Flow Within the Bearing Sector of Aeroengines

2015 ◽  
Author(s):  
Akinola A. Adeniyi ◽  
Hervé P. Morvan ◽  
Kathy A. Simmons
Keyword(s):  
Boundary Conditions ◽  
Computational Study ◽  
Roller Bearing ◽  
Operating Conditions ◽  
Rolling Contact ◽  
Contact Friction ◽  
Outer Race ◽  
Roller Bearings ◽  
Rolling Elements ◽  
Inner Race

The bearing chamber of an aeroengine houses roller bearings and other structural parts. The spatial limitation, high operational speeds of the HP shaft and the proximity to the combustion chamber can make the operating conditions of the bearing chamber challenging. A roller bearing consists of an inner race, an outer race and a cage constraining a number of rolling elements. In the aeroengine application, oil is introduced into the bearing chamber via the inner race regions of the bearing into the rolling elements interstices. This provides lubrication for the roller bearings. The source of heat in the bearing chamber is mainly from rolling contact friction and the high temperature of combustion. Cooling results from the oil transport within the bearing chamber and thus an efficient transport of oil is critical to maintaining the integrity of the entire structure. The bearing chamber contains the oil which is eventually scavenged and recycled for recirculation. Experiments have been conducted over the years on bearing chamber flows but often simplified to create the best emulation of the real aeroengine. The complexity of the bearing chamber structure is also challenging for experimental measurements of the oil characteristic in the roller bearing elements and the bearing chamber compartment. Previous experiments have shown that the oil continuum breaks up in the bearing chamber compartment but it is not quantitatively clear how and what parameters affect these. Previous simulation attempt of bearing chamber, also, have been limited by the boundary conditions for the oil. This work presents a computational fluid dynamics (CFD) transient simulation of flow in the bearing sector in an attempt create boundary conditions for such models. The current results show that the oil emerges in the form of droplets into the bearing chamber compartment with speed of the order of 10% of the shaft rotation.

Investigation of Dynamic Processes in Ball Bearings with Defects

2013 ◽  
Vol 198 ◽  
pp. 651-656 ◽  
Author(s):  
Marijonas Bogdevičius ◽  
Viktor Skrickij
Keyword(s):  
Mathematical Model ◽  
Ball Bearing ◽  
Dynamic Processes ◽  
Experimental Investigations ◽  
Ball Bearings ◽  
Outer Race ◽  
Rolling Element ◽  
Inner Race

The paper considers the dynamics of ball bearings with defects. A mathematical model of a ball bearing with defects is offered. The performed theoretical and experimental investigations of ball bearings with defects are described. Five cases of various defects are investigated, including the defective outer race, the defective inner race, the defective rolling element, the defective inner and outer races, the rolling element and a separator, the worn-out ball bearing.

Numerical investigation of the oil–air distribution inside ball bearings with under-race lubrication

2021 ◽  
pp. 135065012110105
Author(s):  
Le Jiang ◽  
Yaguo Lyu ◽  
Wenjun Gao ◽  
Pengfei Zhu ◽  
Zhenxia Liu
Keyword(s):  
High Speed ◽  
Ball Bearing ◽  
Volume Fraction ◽  
Volume Flow Rate ◽  
Ball Bearings ◽  
Outer Race ◽  
Rotating Speed ◽  
Oil Distribution ◽  
Hole Configuration ◽  
Inner Race

Oil distribution inside the under-race lubricated bearing is crucial for lubrication and cooling of high-speed ball bearings. An under-race lubricated ball bearing is modeled to numerically investigate the effects of operating parameters and feed hole configuration on the distribution behavior of lubricant oil. The results of the numerical simulation indicate that the average oil volume fraction changes with a convex trend as the outer race rotating speed increases, while it changes monotonically with the inner race rotating speed, oil volume flow rate, and oil temperature. The extent of oil spreading on the outer race, cage, ball, and inner race decreases successively. Optimizing the feed hole configuration according to the average oil volume fraction is helpful to achieve precise lubrication of the under-race lubricated ball bearing.

Determination of Rolling Contact Stress Distribution by X-ray Diffraction

1989 ◽  
Vol 33 ◽  
pp. 341-352
Author(s):  
David L. Milan
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Contact Stress ◽  
Rolling Direction ◽  
Roller Bearing ◽  
Rolling Contact ◽  
Outer Race ◽  
Contact Stress Distribution ◽  
Inner Race

AbstractAn investigation was conducted of the potential for detection of the contact stress distribution in tapered roller bearing components made of carburized steel. Various raceway stress distributions were created by control of the profile and alignment of the rolling surfaces. Determination of residual stress in the rolling direction and peak breadth were made using a multiple tilt sin2 ψ technique. The measurements were made at the surface and at depths below the surface. It was found that the distribution of residual stress and peak breadth perpendicular to the rolling direction in the layers below the surface of the inner race correlated highly with the imposed contact stress distribution. The correlation was less in the case of the outer race. The residual stress distribution measured on the surface of the inner race was observed to be inversely proportional to the contact stress distribution.

Nonlinear vibration response analysis of a double-row self-aligning ball bearing due to surface imperfections

2020 ◽  
Vol 234 (3) ◽  
pp. 514-535
Author(s):  
Vivek Parmar ◽  
VH Saran ◽  
SP Harsha
Keyword(s):  
Ball Bearing ◽  
Contact Stiffness ◽  
High Amplitude ◽  
Vibration Response ◽  
System Response ◽  
Response Analysis ◽  
Double Row ◽  
Outer Race ◽  
Rolling Element ◽  
Intermediate Value

This work attempts to study the vibration response of a double-row self-aligning ball bearing due to surface and localized imperfections. For the contact deformation at the ball–race interactions, the Hertzian load–deflection relation is used for the evaluation of time-varying contact stiffness. The elastohydrodynamic theory is applied to find out the central film thickness. For both the inner and outer race waviness cases, the system response is observed as periodic (with vibrations of high amplitude) at [Formula: see text], i.e. multiples of Nb and its vicinity, but gradually turns to quasi-periodic as the value of waviness order reach some intermediate value. In the case of a localized defect, the double impulse phenomenon marks the entry and exit events of the rolling element in and out of the rectangular spall. Hence, this analysis can be used as a diagnostic tool with system dynamic characteristics for distributed and localized defect identification.

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