Two types of rolling-element bearings representing radial loaded and thrust loaded bearings were used for this study. Three hundred forty (340) virtual bearing sets totaling 31400 bearings were randomly assembled and tested by Monte Carlo (random) number generation. The Monte Carlo results were compared with endurance data from 51 bearing sets comprising 5321 bearings. A simple algebraic relation was established for the upper and lower L(sub 10) life limits as function of number of bearings failed for any bearing geometry. There is a fifty percent (50 percent) probability that the resultant bearing life will be less than that calculated. The maximum and minimum variation between the bearing resultant life and the calculated life correlate with the 90-percent confidence limits for a Weibull slope of 1.5. The calculated lives for bearings using a load-life exponent p of 4 for ball bearings and 5 for roller bearings correlated with the Monte Carlo generated bearing lives and the bearing data. STLE life factors for bearing steel and processing provide a reasonable accounting for differences between bearing life data and calculated life. Variations in Weibull slope from the Monte Carlo testing and bearing data correlated. There was excellent agreement between percent of individual components failed from Monte Carlo simulation and that predicted.Vlcek, Brian L. and Hendricks, Robert C. and Zaretsky, Erwin V.Glenn Research CenterBALL BEARINGS; ROLLER BEARINGS; MONTE CARLO METHOD; THRUST BEARINGS; FATIGUE LIFE; FATIGUE TESTS; SIMULATION; WEIBULL DENSITY FUNCTIONS; FAILURE; CONFIDENCE LIMITS

In order to rank bearing materials, lubricants and other design variables using rolling-element bench type fatigue testing of bearing components and full-scale rolling-element bearing tests, the investigator needs to be cognizant of the variables that affect rolling-element fatigue life and be able to maintain and control them within an acceptable experimental tolerance. Once these variables are controlled, the number of tests and the test conditions must be specified to assure reasonable statistical certainty of the final results. There is a reasonable correlation between the results from elemental test rigs with those results obtained with full-scale bearings. Using the statistical methods of W. Weibull and L. Johnson, the minimum number of tests required can be determined. This paper brings together and discusses the technical aspects of rolling-element fatigue testing and data analysis as well as making recommendations to assure quality and reliable testing of rolling-element specimens and full-scale rolling-element bearings.

Engineering asset management encompasses all types of engineered assets including built environment, infrastructure, plant, equipment, hardware systems and components. Following the release of ISO 5500x set of standards, the 9th WCEAM addresses the hugely important issue of what constitutes the body of knowledge in Engineering Asset Management. Topics discussed by Congress delegates are grouped into a number of tracks including strategies for investment and divestment of assets, operations and maintenance of assets, assessments of assets condition, risk and vulnerability, technologies and systems for management of asset, standards, education, training and certification. These proceedings include a sample of the wide range of topics presented during the 9th World Congress on Engineering Asset Management in Pretoria South Africa 28 – 31 October, 2014 and complements other emerging publications and standards that embrace the wide ranging issues concerning the management of engineered physical assets.

Asset Condition, Information Systems and Decision Models, is the second volume of the Engineering Asset Management Review Series. The manuscripts provide examples of implementations of asset information systems as well as some practical applications of condition data for diagnostics and prognostics. The increasing trend is towards prognostics rather than diagnostics, hence the need for assessment and decision models that promote the conversion of condition data into prognostic information to improve life-cycle planning for engineered assets. The research papers included here serve to support the on-going development of Condition Monitoring standards. This volume comprises selected papers from the 1st, 2nd, and 3rd World Congresses on Engineering Asset Management, which were convened under the auspices of ISEAM in collaboration with a number of organisations, including CIEAM Australia, Asset Management Council Australia, BINDT UK, and Chinese Academy of Sciences, Beijing University of Chemical Technology, China. Asset Condition, Information Systems and Decision Models will be of particular interest to finance, maintenance, and operations personnel whose roles directly affect the capability value of engineering asset base, as well as asset managers in both industry and government.

Rolling-contact fatigue tests were performed on SAE 52100 207-size deep-groove ball bearing determine the relation between bearing fatigue life and actual bearing component hardness differences and the effect of actual component hardness differences on bearing fatigue life scatter. The 207-size bearings with inner and outer races from the same heat of SAE 52100 material and with nominal Rockwell C hardnesses of 63 were assembled with SAE 52100 balls from the same heat of material tempered to nominal Rockwell C hardnesses of 60, 63, 65, and 66. Test conditions included an inner race speed of 2750 rpm, a radial load of 1320 pounds, which produced maximum Hertz stresses of 352 000 and 336 000 psi at the inner and the outer races, respectively, and a highly purified naphthenic mineral oil as the lubricant. Subsequent to testing, the bearings were disassembled, and all component hardnesses were measured. The bearings were regrouped according to their actual values of AH for Rockwell C hardness increments of 0. 5 and 1. 0, where AH is the difference between the actual hardness of the rolling elements in the bearing and the actual hardness of the inner race. The fatigue life and scatter results were compared with component hardness combinations and data previously obtained from the five-ball fatigue tester. The following results were obtained