Effect of Pillow Block Deformation on Ball Bearing Load Distribution

2004 ◽  
Author(s):  
Patrick A. Tibbits
Keyword(s):  
Load Distribution ◽  
Variable Stiffness ◽  
Hertzian Contact ◽  
Spring Element ◽  
Bearing Life ◽  
Bearing Load ◽  
Solid Finite Elements ◽  
Program Output ◽  
Bearing Rings ◽  
Geometric Changes

Support structure deflection distorts bearing rings, redistributes loads over bearing balls, and affects bearing life. In this study, solid finite elements modeled a shaft, bearing inner ring, outer ring, and pillow block. A nonlinear spring element represented each of the bearing balls. The force-versus-deflection curve of the spring element modeled the variable stiffness of the ball/raceway Hertzian contact. The curve also incorporated the diametrical clearance of the bearing to determine if each ball contacted the raceways. Further modification of the curve compensated for the compliance of the nodes of solid elements that modeled raceways. This construct avoided computationally expensive surface-to-surface contact calculations. Program output included deflection of the pillow block and a listing of spring element forces, which characterized the ball loads. The maximum ball load decreased for a bearing installed in a pillow block, and life increased. Material or geometric changes that reduced pillow block stiffness further improved life.

Effects of Load Distribution on Life of Radial Roller Bearings

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
Takafumi Nagatomo ◽  
Ken Takahashi ◽  
Yoshiaki Okamura ◽  
Takehiko Kigawa ◽  
Shoji Noguchi
Keyword(s):  
Load Distribution ◽  
Rolling Bearing ◽  
Outer Ring ◽  
Contact Conditions ◽  
Internal Load ◽  
Load Distributions ◽  
Bearing Life ◽  
Rolling Elements ◽  
Endurance Tests ◽  
Bearing Rings

An external load applied to a radial rolling bearing is distributed among the rolling elements. In many applications, the bearing internal load distribution may be altered by the elastic deformations of the bearing rings. This alteration can have an effect on bearing life. The objective of this study is to investigate the effect of load distribution on bearing life, both theoretically and experimentally, using several housing models which provide different contact conditions between the housing bore and the outer ring. This paper first presents a newly developed method of determining dynamic load distributions with an optical fiber strain sensor. The measurements of the load distribution for the housing models by using this method have shown that the contact condition between the housing bore and the outer ring affects the load distribution, and the effect of the load distribution on the bearing life has been confirmed by the theoretical calculation of the bearing life. Furthermore, endurance tests using dented bearings were performed to validate the effect of load distribution on bearing life. The results of the tests have substantiated that the bearing life is substantially affected by the load distribution; moreover, it has been shown that there is a linear relationship between the calculated lives and the experimental ones.

FEM Simulation and Life Optimization of Tandem Roller Thrust Bearing

2005 ◽  
Author(s):  
Patrick A. Tibbits
Keyword(s):  
Contact Stress ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Fem Simulation ◽  
Rolling Contact ◽  
Spring Element ◽  
Contact Fatigue Life ◽  
Solid Finite Elements ◽  
Rotary Equipment ◽  
Program Output

Tandem thrust roller bearings carry high axial loads in rotary equipment such as mud pumps or extruders. Deflection of the bearing plates redistributes loads over rollers, and affects bearing life. In this study, solid finite elements modeled a shaft, housing and two stages of bearing plates. A line of spring elements represented each row of rollers. The stiffness of the line of spring elements modeled the stiffness of each roller/raceway non-Hertzian line contact. Modification of the spring element stiffness compensated for the compliance of the nodes of solid elements that modeled the bearing plates. This construct avoided computationally expensive surface-to-surface contact calculations. Further computational savings accrued from modeling the bearing and shaft assembly as axisymmetric. Program output included deflection of the bearing plates and a listing of spring element forces, which characterized the distribution of load over the length of the rollers. Bearings with optimized geometry had decreased maximum contact stress, more uniform distribution of contact stress over the length of each roller, and longer estimated rolling contact fatigue life.

Load Calculation and Life Prediction for Auto Water Pump Bearing

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
Zhengmei Li ◽  
Qiong Zhou ◽  
Jianping Tang ◽  
Jianwen Wang ◽  
Qi An
Keyword(s):  
Load Distribution ◽  
Normal Load ◽  
Analytical Calculation ◽  
Engineering Application ◽  
Water Pump ◽  
Bearing Load ◽  
Calculation Results ◽  
Bearing Design ◽  
Bearing Loads

Taking the water pump bearing with one roller row (WR)-type auto water pump bearing as a research sample, an analytical calculation method is developed to improve the accuracy and efficiency of the current calculations for the bearing loads and life in engineering application. Considering the misalignment due to the deflection of the bearing spindle, the bearing internal loads and deformations under the action of the complicated external space loads are obtained. The bearing fatigue life including the lives of the rollers and the balls is also calculated with considering the non-normal load distribution caused by the spindle deflection and the roller tilt. The bearing load and life calculation results are compared with those calculated by the traditional method in which the deflection of the bearing spindle and the roller tilt are ignored. The effects of the bearing spindle deflection on the load distribution and the life of the auto water pump bearing are analyzed and discussed. The life decrease in the auto water pump bearing is significant due to the deflection of the bearing spindle and it is recommended to give more attention to this deflection for the high quality of the bearing design and calculation.

Rolling Element Bearing Non-Linearity Effects

2000 ◽  
Author(s):  
N. S. Feng ◽  
E. J. Hahn
Keyword(s):  
Equations Of Motion ◽  
Rolling Element Bearing ◽  
Radial Clearance ◽  
Rotor Systems ◽  
Bearing Life ◽  
Rolling Element ◽  
Bearing Load ◽  
Rolling Elements ◽  
Element Bearing ◽  
Negative Clearance

Non-linearity effects in rolling element bearings arise from two sources, viz. the Hertzian force deformation relationship and the presence of clearance between the rolling elements and the bearing races. Assuming that centrifugal effects may be neglected and that the presence of axial preload is appropriately reflected in a corresponding change in the radial clearance, this paper analyses a simple test rig to illustrate that non-linear phenomena such as synchronous multistable and nonsynchronous motions are possible in simple rigid and flexible rotor systems subjected to unbalance excitation. The equations of motion of the rotor bearing system were solved by transient analysis using fourth order Runge Kutta. Of particular interest is the effect of clearance, governed in practice by bearing specification and the amount of preload, on the vibration behaviour of rotors supported by ball bearings and on the bearing load. It is shown that in the presence of positive clearance, there exists an unbalance excitation range during which the bearing is momentarily not transmitting force owing to contact loss, resulting in rolling element raceway impact with potentially relatively high bearing forces; and indicating that for long bearing life, operation with positive clearance should be avoided in the presence of such unbalance loading. Once the unbalance excitation is high enough to avoid such contact loss, it is the bearings with zero or negative clearance which produce maximum bearing forces.

Analytical determination of the optimal clearance for the fatigue life of ball bearing under different load conditions

2021 ◽  
pp. 1-28
Author(s):  
Bin Fang ◽  
Jinhua Zhang
Keyword(s):  
Fatigue Life ◽  
Load Distribution ◽  
Life Prediction ◽  
Ball Bearing ◽  
Operating Conditions ◽  
Analytical Determination ◽  
Parameters Selection ◽  
Bearing Life ◽  
Structural Design Optimization ◽  
Load Conditions

Abstract In this paper, a comprehensive analytical model for the fatigue life prediction of ball bearing in various operating conditions is presented. Not only the internal clearance variations induced by the centrifugal expansion and assembly interference, but also ball inertia forces and ball-raceway separations are fully considered in theoretical modeling to achieve accurate life prediction of ball bearing. The model has been validated by comparison with the static results in previous literature. Based on this, the results of the load distribution and fatigue life versus the internal clearance of ball bearing under various operating conditions are studied. The results show that there is always an optimal clearance to maximize bearing fatigue life for the radial load or the combined load conditions, and the size of the optimal clearance for bearing life is determined by both the load conditions and rotating speeds to ensure the uniformity of the internal load distribution of the ball bearing. Therefore, the above theoretical and conclusions can be used in structural design optimization and assembly parameters selection of ball bearing to maximize the life characteristic.

Theoretical Study on the Influence of Planet Gear Rim Thickness and Bearing Clearance on Calculated Bearing Life

2019 ◽  
Vol 142 (3) ◽  
Author(s):  
Andreas Fingerle ◽  
Jonas Hochrein ◽  
Michael Otto ◽  
Karsten Stahl
Keyword(s):  
High Efficiency ◽  
Roller Bearing ◽  
The Body ◽  
Fem Model ◽  
Bearing Life ◽  
Bearing Load ◽  
Rolling Elements ◽  
Planet Gear ◽  
Cylindrical Roller Bearing ◽  
Cylindrical Roller

Abstract Planetary gearboxes are becoming more popular due to their high-power density and potentially high efficiency. When the planet bearings are internally mounted, the body of the planet gear has to be hollow. The demand for large outer diameters due to high-load requirements might result in a small planet rim thickness. Depending on the rim thickness, its rigidity may become very low. Due to the low stiffness and the special load conditions caused by the double meshing, the deformation of the planet and its bearings are unique. In this paper, the influence of rim thickness on bearing load and lifetime is examined. The analysis is performed with a finite element method (FEM) model of a planet rim with a built-in cylindrical roller bearing. With the resulting planet deformation from the FEM calculation, the load distribution on the rolling elements in the bearing and the bearing lifetime according to ISO/TS 16281:2008 has been evaluated.

Theoretical Study on the Influence of Planet Gear Rim Thickness and Bearing Clearance on Calculated Bearing Life

2019 ◽  
Author(s):  
Andreas Fingerle ◽  
Jonas Hochrein ◽  
Michael Otto ◽  
Karsten Stahl
Keyword(s):  
High Efficiency ◽  
Roller Bearing ◽  
The Body ◽  
Fem Model ◽  
Bearing Life ◽  
Bearing Load ◽  
Rolling Elements ◽  
Planet Gear ◽  
Cylindrical Roller Bearing ◽  
Cylindrical Roller

Abstract Planetary gearboxes are becoming more popular due to their high power density and potentially high efficiency. When the planet bearings are internally mounted, the body of the planet gear has to be hollow. The demand for large outer diameters due to high load requirements might result in a small planet rim thickness. Depending on the rim thickness, its rigidity may become very low. Due to the low stiffness and the special load conditions caused by the double meshing, the deformation of the planet and its bearings are unique. In this paper, the influence of rim thickness on bearing load and lifetime are examined. The analysis is performed with an FEM model of a planet rim with a built-in cylindrical roller bearing. With the resulting planet deformation from the FEM calculation, the load distribution on the rolling elements in the bearing and the bearing lifetime according to ISO/TS 16281:2008 have been evaluated.

Fatigue Life Prediction for Large-Diameter Elastically Constrained Ball Bearings

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Jerzy T. Sawicki ◽  
Samuel A. Johansson ◽  
John H. Rumbarger ◽  
Ronald B. Sharpless
Keyword(s):  
Fatigue Life ◽  
Load Distribution ◽  
Life Prediction ◽  
Large Diameter ◽  
Roller Bearing ◽  
Fatigue Life Prediction ◽  
Design Criteria ◽  
Standard Design ◽  
Critical Components ◽  
Bearing Rings

The application of large-diameter bearing rings and the thereof inherited low stiffness make them susceptible to local distortions caused by their surrounding structures, which are often under heavy loads. The standard accepted design criteria for these bearings are based on the estimation of the internal load distribution of the bearing, under the assumption of rigid circular and flat supporting structures, that keep the bearing inner and outer races in circular, flat, i.e., not deformed shapes. However, in the presence of structural distortions, the element load distribution can be severely altered and cannot be predicted via the standard design criteria. Therefore, the application of large-diameter ball and roller bearing rings as the critical components in rotating machines becomes more of a design task than making a catalog selection. The analytical and finite element approach for fatigue life prediction of such a bearing application is presented. The undertaken approach and the results are illustrated based on the analysis and fatigue life simulation of the computed tomography scanner’s main rotor bearing. It has been demonstrated that flexibility of the rings can significantly reduce the fatigue life of the ball bearing.

Adjustment of Blank Holding Force Distribution Utilizing a Multi-Point Die Support System

2014 ◽  
Vol 622-623 ◽  
pp. 1117-1123
Author(s):  
Takahiro Ohashi ◽  
Wan Tong
Keyword(s):  
Support System ◽  
Load Distribution ◽  
Side Surface ◽  
Strain Gauges ◽  
Force Distribution ◽  
Support Structure ◽  
Support Unit ◽  
Bearing Load ◽  
Ball Contact ◽  
Blank Holding Force

In this study, the authors employ a multi-point die-support structure to hold the upper die for deep drawings in order to adjust the distribution of the blank holding force (BHF) so as to eliminate wrinkles. The developed multi-point support structure has 12 support cells (support units) between the upper die and the outer slide of a double-action press; the cells are metal cylinders working as springs. The support unit has a ball contact at the interface with the upper die, and the interface freely rotates and slides horizontally. The support unit has strain gauges on the side surface, and the bearing load at each unit can be determined, as well as the elastic deformation. The bearing load distribution is observed through a trial blow, and then the support units are manually relocated to better distribute the supporting points to create the appropriate BHF distribution. To demonstrate the efficiency of the suggested structure, the authors perform deep drawing with off-centered setting of a blank to create wrinkles intentionally. They then employ the multi-point die-support system, relocate the support units, and eliminate wrinkles.

Sign in / Sign up

Export Citation Format

Share Document