The present investigation examined the vertical and horizontal thermoelastic changes in the outside diameter of a turbojet-engine roller bearing. Thermal loads were imparted to the bearing by the hands of a bearing technician during a rework operation. A worst-case analysis was examined by assuming a three-minute dwell time and diametrically symmetric thermal loading. Contact temperature was experimentally determined and used in conjunction with a numerical model to simulate thermal propagation throughout the bearing outer ring. Diametric deflection data, obtained using the contact temperature in conjunction with analytic and finite elements, have been shown for comparative purposes. Experimental diametric expansions of the bearing outer ring were determined and compared with the predicted results. Assuming a worst-case scenario, this investigation yielded vertical expansions in the bearing outer ring’s diameter, which would be problematic for some bearings during the rework operation; appropriate corrective action was discussed.

Issue Section:
Gas Turbines: Structures and Dynamics
Topics:
Bearings, Deformation, Engines, Inspection, Maintenance, Thermoelasticity, Turbojets, Temperature, Computer simulation, Corrective actions, Deflection, Finite element analysis, Roller bearings, Stress
1.
Holman, J. P., 1984, Experimental Methods for Engineers, 4th. ed., McGraw-Hill, New York.
2.
Kochevar, A. J., 1993, “Thermoelastic Deformation Analysis of a Turbojet Bearing Undergoing Maintenance Inspection,” M.S. thesis, The University of Oklahoma, Norman, OK.
3.
Kochevar, A. J., and Bert, C. W., 1995, “Thermal Deformations in Thin Circular Rings Subjected to Localized Heating,” Journal of Thermal Stresses, to appear.
4.
Pratt & Whitney Co., 1963, “Pratt & Whitney Electrolimit Supermicrometer (Model B) Instruction Book,” West Hartford, CT.
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 by The American Society of Mechanical Engineers
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