GLTRS--Glenn
TITLE AND SUBTITLE:
Simulating Fatigue Crack Growth in Spiral Bevel Gears

AUTHOR(S):
Lisa E. Spievak, Paul A. Wawrzynek, and Anthony R. Ingraffea

REPORT DATE:
May 2000

FUNDING NUMBERS:
WU-581-30-13-00
NAG3-1993
1L162211A47A


PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES):
Cornell University
Cornell Fracture Group
641 Frank Rhodes Hall
Ithaca, New York 14853

PERFORMING ORGANIZATION REPORT NUMBER:
E-12287

SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES):
U.S. Army Research Laboratory
Cleveland, Ohio 44135-3191
and
NASA Glenn Research Center
Cleveland, Ohio 44135-3191

REPORT TYPE AND DATES COVERED:
Final Contractor Report

SPONSORING/MONITORING AGENCY REPORT NUMBER:
NASA CR-2000-210062
ARL-CR-451

SUPPLEMENTARY NOTES:
Project Manager, David G. Lewicki, Structures and Acoustics Division, NASA Glenn Research Center, organization code 5950, (216) 433-3970.

ABSTRACT:
The majority of helicopter transmission systems utilize spiral bevel gears to convert the horizontal power from the engine into vertical power for the rotor. Due to the cyclical loading on a gear's tooth, fatigue crack propagation can occur. In rotorcraft applications, a crack's trajectory determines whether the gear failure will be benign or catastrophic for the aircraft. As a result, the capability to predict crack growth in gears is significant. A spiral bevel gear's complex shape requires a three dimensional model of the geometry and cracks. The boundary element method in conjunction with linear elastic fracture mechanics theories is used to predict arbitrarily shaped three dimensional fatigue crack trajectories in a spiral bevel pinion under moving load conditions. The predictions are validated by comparison to experimental results. The sensitivity of the predictions to variations in loading conditions and crack growth rate model parameters is explored. Critical areas that must be understood in greater detail prior to predicting more accurate crack trajectories and crack growth rates in three dimensions are identified.

SUBJECT TERMS:
Gears; Spiral-bevel gears; Crack propagation; Fracture mechanics;
Boundary element method

NUMBER OF PAGES:
125

PDF AVAILABLE FROM URL:
2000/CR-2000-210062.pdf
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