Strength Against Fracture of End Hemispherical Cavity Roller Under Static Loading: Experimental and Simulation Investigation

2020 ◽  
Vol 143 (7) ◽  
Author(s):  
Paresh C. Chhotani ◽  
Dipak P. Vakharia
Keyword(s):  
Fatigue Life ◽  
Maximum Shear Stress ◽  
Contact Stresses ◽  
Fracture Load ◽  
Experimental Results ◽  
Rolling Element Bearing ◽  
Catastrophic Failure ◽  
Rolling Element ◽  
Fracture Tests ◽  
Novel Concept

Abstract Enhancement in fatigue life of the rolling-element bearing has been captivating since years. The hollow concept had been triggered years back; however, it could not catch widespread applications due to catastrophic failure. Thus, any novel concept of the rolling element must be assessed for its strength against catastrophic failure before competing for better fatigue life on field with other alternatives. This paper commences with the outcomes of the comparative assessment of the experimental evaluation of strength against fracture under static loads for layered and hollow rollers with solid rollers, which devise the requirements for new concepts. The end hemispherical cavity (EHC) roller concept, being a proper geometrical blending of solidity and hollowness, prospects to overcome the strength concern along with a considerable reduction in contact stresses. Thus, experimental investigation was conducted with full-bearing fracture tests and individual roller specimens fracture tests for five variants: EHC, solid, layered, 61H, and 37H (hollow rollers with 61% and 37% hollowness, respectively). The simulations were carried out to support the outcomes of experimental trials. The experimental results with full-bearing samples and individual roller specimens demonstrated ranking as follows: EHC, 37H, layered, and 61H. The EHC roller concept was substantiated to be stronger than hollow and layered rollers besides prompting appreciable reduction in contact stresses compared with the solid roller. The simulation results agreed well with experimental results of fracture tests, and the recommendations from findings of failure theories (maximum normal stress, distortion energy, and maximum shear stress) adopted for estimating fracture load for rollers have been discussed.

Stiffness Optimization of Hollow Cylindrical Rolling Element Bearing

2008 ◽  
Author(s):  
P. H. Darji ◽  
D. P. Vakharia
Keyword(s):  
Load Capacity ◽  
Contact Problems ◽  
Contact Stresses ◽  
Rolling Element Bearing ◽  
Thin Wall ◽  
Element Analysis ◽  
Normal Loading ◽  
Rolling Element ◽  
Rolling Elements ◽  
Minimum Stress

Since being originally introduced, cylindrical rolling element bearings have been significantly improved, in terms of their performance and working life. A major objective has been to decrease the Hertz contact stresses at the roller–raceway interfaces, because these are the most heavily stressed areas in a bearing. It has been shown that bearing life is inversely proportional to the stress raised to the ninth power (even higher). Investigators have proposed that under large normal loads a hollow element with a sufficiently thin wall thickness will deflect appreciably more than a solid element of the same size. An improvement in load distribution and thus load capacity may be realized, as well as contact stress is also reduced considerably by using a bearing with hollow rolling elements. Since for hollow rolling element no method is available for the calculation of contact stresses and deformation. The contact stresses in hollow members are often calculated by using the same equations and procedures as for solid specimens. This approach seems to be incorrect. Recently, the Finite Element Analysis (FEA) has been successfully used to evaluate contact problems for the roller bearings. Investigations have been made for hollow rollers in pure normal loading. Different hollowness percentages ranging from 0% to 90% have been analysed in FEA software to find the optimum percentage hollowness which gives minimum stress and finally longest fatigue life.

Ball Spalling in Rolling Element Bearings: Decrease in Rolling Contact Fatigue Life Due to Inferior Microstructure and Manufacturing Processes

2021 ◽  
Author(s):  
Graham Keep ◽  
Mark Wolka ◽  
Beth Brazitis
Keyword(s):  
Fatigue Life ◽  
Rolling Contact Fatigue ◽  
Microstructural Analysis ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Rolling Element Bearing ◽  
Bench Test ◽  
Bearing Life ◽  
Rolling Element ◽  
Contact Fatigue Life

Abstract Through hardened steel ball fatigue failure is an atypical mode of failure in a rolling element bearing. A recent full-scale bench test resulted in ball spalling well below calculated bearing life. Subsequent metallurgical analysis of the spalled balls found inferior microstructure and manufacturing methods. Microstructural analysis revealed significant carbide segregation and inclusions in the steel. These can result from substandard spheroidized annealing and steel making practices. In addition, the grain flow of the balls revealed a manufacturing anomaly which produced a stress riser in the material making it more susceptible to crack initiation. The inferior manufactured balls caused at least an 80% reduction in rolling contact fatigue life of the bearing.

scholarly journals Dynamic Capacity and Surface Fatigue Life for Spur and Helical Gears

1976 ◽  
Vol 98 (2) ◽  
pp. 267-274 ◽  
Author(s):  
J. J. Coy ◽  
D. P. Townsend ◽  
E. V. Zaretsky
Keyword(s):  
Fatigue Life ◽  
Gear Train ◽  
Rolling Element Bearing ◽  
Tangential Load ◽  
Dynamic Capacity ◽  
Probability Of Survival ◽  
Surface Fatigue ◽  
Rolling Element ◽  
Life Model ◽  
Life Predictions

A mathematical model for surface fatigue life of gear, pinion, or entire meshing gear train is given. The theory is based on the statistical approach used by Lundberg and Palmgren for rolling-element bearings. Also equations are presented which give the dynamic capacity of the gear set. The dynamic capacity is the transmitted tangential load which gives a 90 percent probability of survival of the gear set for one million pinion revolutions. The analytical results were compared with test data for a set of AISI 9310 spur gears operating at a maximum Hertz stress of 1.71 × 109 N/m2 (248,000 psi) and 10,000 rpm. The theoretical life predictions were very good when material constants obtained from rolling-element bearing tests were used in the gear life model.

Analysis of a Rolling-Element Idler Gear Bearing Having a Deformable Outer-Race Structure

1963 ◽  
Vol 85 (2) ◽  
pp. 273-278 ◽  
Author(s):  
A. B. Jones ◽  
T. A. Harris
Keyword(s):  
Fatigue Life ◽  
High Speed ◽  
Roller Bearing ◽  
Rolling Element Bearing ◽  
Outer Ring ◽  
Outer Race ◽  
Rolling Element ◽  
Rolling Elements ◽  
Planet Gear ◽  
Bearing Rings

Conventional calculations of ball and roller bearing carrying capacity and fatigue life assume that the raceway bodies are rigid structures and that all elastic deformation occurs at the rolling elements’ contact with the raceways. In many instances, and particularly with aircraft applications, the bearing rings and their supports cannot be considered rigid. One such application is the planet gear in a transmission. This report develops a theory whereby the effects of the elastic distortions of the outer race of a rolling-element bearing on the internal load distribution and fatigue life of the bearing can be considered. The theory has been programmed for a high-speed, digital computer. An example of calculation for a planet gear roller bearing whose outer race is integral with the gear and of relatively thin section is given. The distortions of the flexible outer ring cause a significantly lower bearing fatigue life (L10) than would occur if the outer ring were rigid and considering a practical range of bearing diametral clearances. Mr. Jones developed the theoretical analysis for this paper and Mr. Harris provided the programming and the experimental data.

scholarly journals Fatigue Life of High-Speed Ball Bearings With Silicon Nitride Balls

1975 ◽  
Vol 97 (3) ◽  
pp. 350-355 ◽  
Author(s):  
R. J. Parker ◽  
E. V. Zaretsky
Keyword(s):  
Fatigue Life ◽  
Silicon Nitride ◽  
High Speed ◽  
Bearing Steel ◽  
Rolling Element Bearing ◽  
Ball Bearings ◽  
Rolling Element ◽  
Low Mass ◽  
Element Bearing ◽  
Steel Balls

Hot-pressed silicon nitride was evaluated as a rolling-element bearing material. This material has a low specific gravity (41 percent that of bearing steel) and has a potential application as low mass balls for very high-speed ball bearings. The five-ball fatigue tester was used to test 12.7-mm- (0.500-in-) dia silicon nitride balls at maximum Hertz stresses ranging from 4.27 × 109 N/m2 (620,000 psi) to 6.21 × 109 N/m2 (900,000 psi) at a race temperature of 328K (130 deg F). The fatigue life of NC-132 hot-pressed silicon nitride was found to be equal to typical bearing steels and much greater than other ceramic or cermet materials at the same stress levels. A digital computer program was used to predict the fatigue life of 120-mm- bore angular-contact ball bearings containing either steel or silicon nitride balls. The analysis indicates that there is no improvement in the lives of bearings of the same geometry operating at DN values from 2 to 4 million where silicon nitride balls are used in place of steel balls.

Research on Contact Fatigue Properties of Some Materials Used for Heavy Load Gear

2010 ◽  
Vol 139-141 ◽  
pp. 360-363
Author(s):  
Ying Xia Yu ◽  
Bo Lin He ◽  
Er Yu Shao
Keyword(s):  
Fatigue Life ◽  
Crack Propagation ◽  
Maximum Shear Stress ◽  
Contact Fatigue ◽  
Fatigue Tests ◽  
Experimental Results ◽  
Fatigue Properties ◽  
Heavy Load ◽  
Contact Fatigue Life ◽  
Materials Used

The contact fatigue tests were carried out using three kind of steel(45, 42CrMo, 40CrNi2Mo) which were quenched and tempered to the same medium hardness(HRC37±1). The experimental equipment is JPM-1 type contact fatigue tester. During the experiment process, the contact stress is 1600MPa and the surface roughness is 0.4 um. The crack initiation and the crack propagation direction were observed by using SEM. The contact fatigue failure mechanism was also analyzed. The experimental results were analyzed by using Weibull distribution. The experimental results show that the contact fatigue crack was initiated in the roller surface. With increasing of the cycle, the initiated crack propagates into subsurface and becomes to pitting. The pitting becomes bigger and bigger and leads to failure finally. The maximum shear stress is the main driving force for the crack propagation. The contact fatigue life increases in sequence of 45, 42CrMo, 40CrNi2Mo. The contact fatigue life has the relationship with the shearing resistant stress Тk. About the same carbon content, the value of the shearing resistant stress Тk becomes greater with increasing the alloying elements. The best material used for making heavy duty gear is 40CrNi2Mo steel.

scholarly journals The Series Hybrid Bearing—A New High Speed Bearing Concept

1972 ◽  
Vol 94 (2) ◽  
pp. 117-122 ◽  
Author(s):  
W. J. Anderson ◽  
D. P. Fleming ◽  
R. J. Parker
Keyword(s):  
Fatigue Life ◽  
High Speed ◽  
Ball Bearing ◽  
Rolling Element Bearing ◽  
Speed Ratio ◽  
Shaft Speed ◽  
Rolling Element ◽  
Element Bearing ◽  
Hybrid Bearing ◽  
Inner Race

The series-hybrid bearing couples a fluid-film bearing with a rolling-element bearing such that the rolling-element bearing inner race runs at a fraction of shaft speed. A series-hybrid bearing was analyzed and experiments were run at thrust loads from 100 to 300 lb and speeds from 4000 to 30,000 rpm. Agreement between theoretical and experimental speed sharing was good. The lowest speed ratio (ratio of ball bearing inner-race speed to shaft speed) obtained was 0.67. This corresponds to an approximate reduction in DN value of 1/3. For a ball bearing in a 3 million DN application, fatigue life would theoretically be improved by a factor as great as 8.

Rolling element bearing multi-fault diagnosis using morphological joint time–frequency adaptive kernel–based semi-smart framework

2021 ◽  
pp. 107754632110228
Author(s):  
Sunil Lonare ◽  
Neville Fernandes ◽  
Aditya Abhyankar
Keyword(s):  
Wavelet Transform ◽  
Fault Detection ◽  
Fault Location ◽  
Operating Conditions ◽  
Experimental Results ◽  
Rolling Element Bearing ◽  
Time Frequency ◽  
Rolling Element ◽  
Adaptive Kernel ◽  
Element Bearing

The wavelet transform is a state of the art time–frequency analysis method for rolling element bearing localized fault detection, using vibration signals. When these localized faults are present at more than one location of bearing, it is called “multi-fault.” Using wavelet transform fault detection with high severity is possible, but this method fails to detect the presence of fault as well as the location of a fault in multi-fault case and when the fault severity is low. The identification of the fault location, in rolling element bearing when more than one location of bearing contains a localized fault, is very useful for further root cause analysis; therefore, multi-fault detection is a challenge today. In the present work, a new morphological joint time–frequency adaptive kernel–based semi-smart framework is developed to address this challenge. In morphological joint time–frequency adaptive kernel, the kernel will adapt itself by analyzing the basic morphology of the bearing under observation and by considering the location of a fault. The simulation and experimental results show that morphological joint time–frequency adaptive kernel–based framework is able to detect low severity single fault as well as the location of the localized fault on rolling element bearing in the multi-fault case. Experimental results also show that the morphological joint time–frequency adaptive kernel framework is independent of bearing dimensions as well as machine operating conditions.

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