Accession Number : ADA309875

Title :   Gear Crack Propagation Investigations.

Descriptive Note : Technical rept.,

Corporate Author : NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH LEWIS RESEARCH CEN TER

Personal Author(s) : Lewicki, David G. ; Ballarini, Roberto

PDF Url : ADA309875

Report Date : JAN 1996

Pagination or Media Count : 12

Abstract : Analytical and experimental studies were performed to investigate the effect of gear rim thickness on crack propagation life. The FRANC (FRacture ANalysis Code) computer program was used to simulate crack propagation. The FRANC program used principles of linear elastic fracture mechanics, finite element modeling, and a unique re-meshing scheme to determine crack tip stress distributions, estimate stress intensity factors, and model crack propagation. Various fatigue crack growth models were used to estimate crack propagation life based on the calculated stress intensity factors. Experimental tests were performed in a gear fatigue rig to validate predicted crack propagation results. Test gears were installed with special crack propagation gages in the tooth fillet region to measure bending fatigue crack growth. Good correlation between predicted and measured crack growth was achieved when the fatigue crack closure concept was introduced into the analysis. As the gear rim thickness decreased, the compressive cyclic stress in the gear tooth fillet region increased. This retarded crack growth and increased the number of crack propagation cycles to failure.

Descriptors :   *CRACK PROPAGATION, STRESSES, COMPUTER PROGRAMS, MATHEMATICAL MODELS, THICKNESS, CLOSURES, EXPERIMENTAL DATA, DISTRIBUTION, EXPERIMENTAL DESIGN, FINITE ELEMENT ANALYSIS, ELASTIC PROPERTIES, INTENSITY, TEST METHODS, TEST EQUIPMENT, FRACTURE(MECHANICS), CYCLES, CODING, LINEARITY, FATIGUE, FATIGUE(MECHANICS), GAGES, GEARS, COMPRESSIVE PROPERTIES, RETARDATION.

Subject Categories : Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE