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Bearing Analytical Software Development and Validation


OBJECTIVE: Update and validate bearing analytical software with improved thermal and life models for bearings in critical applications such as gas turbines and engine related drive systems. DESCRIPTION: The thermal management and rolling contact fatigue (RCF) life of bearings in modern turbine engines are increasingly challenged as engine speeds, loads, and temperatures are increased to meet improved cycle efficiency. This trend should increase for next generation turbine engines that improve fuel efficiency. Heat generation and life models in commercial-of-the-shelf (COTS) bearing analytical codes used in the gas turbine industry have not been updated in over two decades and are now inadequate to accurately predict bearing life and heat generation. Also, existing life models are unable to predict the rolling contact life of the next generation bearing materials such as Pyrowear 675 steel, nitride M50 and M50 NiL, and bearings operating with silicon nitride rolling elements. This program will develop improved bearing life and heat generation models to meet this requirement. Improved lubricant traction models will be developed to improve bearing heat generation analysis. Bearing life models will consider how the next- generation bearing steels and use of silicon nitride ceramic rolling elements contribute to bearing life. Lubricant traction, bearing heat generation, and bearing life models will be validated using experimental data. The new models will be integrated into a bearing analytical code currently used by industry to predict bearing performance. The bearing geometry, applied loads, rotational speeds and thermal environment will be used to define the bearing operating and boundary conditions. The analytical code will include all internal loads, kinematics, and lubricant properties to achieve accurate bearing life and heat generation prediction. The analytical code will have a PC graphical user interface (GUI) for input and output. Output will be summarized in tablature and graphical form for easy interpretation by the user. Potential bidders are highly encouraged to work with a gas turbine engine company to ensure the approach is relevant and for access to the latest bearing heat generation and life data. It is desired that the software and associated documentation be delivered at the end of the Phase II for additional evaluation by U.S. Government personnel. PHASE I: Demonstrate the feasibility of the improved analytical code to effectively model current traction, bearing heat generation, and life data for a chosen bearing system. The improved model will be compared to state-of-the-art models currently in use. PHASE II: Further develop the analytical software into a useable product and validate results with obtained experimental data for lubricant traction, bearing heat generation, and bearing fatigue life. Develop an effective GUI to assist users in ease of operation. An end of contract demonstration should be conducted for interested government personnel. PHASE III: The small business will provide commercial availability of the analytical code to the aerospace industry for applications requiring high precision bearing designs, e.g., turbine engines, satellite gyroscopes, and rocket pumps. The technology has application for both military and commercial systems. REFERENCES: 1. Gupta, P.K., Advanced Dynamics of Rolling Elements, Springer-Verlag, New York (1984). 2. Crecelius, W.J., and Pirvics, J.,"Computer Program Operational on SHABERTH a Computer Program for the Analysis of the Steady State and Transient Thermal Performance of Shaft-Bearing Systems,"AFAPL-TR-76-90 (1976). 3. Woods, C.M.,"Modification of the SHABERTH Bearing Code to Incorporate RP-1 and a Discussion of the Traction Model,"NASA Technical Paper 3017. 4. Zaretsky, E.V., Poplawski, J.V., and Peters, S.M.,"Comparison of Life Theories for Rolling-Element Bearings,"Trib. Trans., 39, 2, pp. 237-248 and 501-503, (1996). 5. Forster, N.H., Svendsen, V.R., Givan, G.D., Thompson, K.L., Dao, N.H., and Nicholson, B.D.,"Parametric Testing and Heat Generation Modeling of 133-mm Bore Ball Bearings: Part I-Results with Metal Rolling Elements,"Trib. Trans., 54, 2, pp. 315-324, (2011).
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