Accession Number : ADA314602

Title :   Effect of Rim Thickness on Gear Crack Propagation Path.

Descriptive Note : Technical memo.,

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

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

PDF Url : ADA314602

Report Date : AUG 1996

Pagination or Media Count : 15

Abstract : Analytical and experimental studies were performed to investigate the effect of rim thickness on gear tooth crack propagation. The goal was to determine whether cracks grew through gear teeth or through gear rims for various rim thicknesses. A finite element based computer program (FRANC, FRacture ANalysis Code) simulated gear tooth crack propagation. The analysis used principles of linear elastic fracture mechanics. Quarter-point, triangular elements were used at the crack tip to represent the stress singularity. The program had an automated crack propagation option in which cracks were grown numerically using an automated re-meshing scheme. Crack tip stress intensity factors were estimated to determine crack propagation direction. Gears with various backup ratios (rim thickness divided by tooth height) were tested to validate crack path predictions. Gear bending fatigue tests were performed in a spur gear fatigue rig. From both predictions and tests, gears with backnp ratios of 3.3 and 1.0 produced tooth fractures while a backup ratio of 0.3 produced rim fractures. For a backup ratio of 0.5, the experiments produced rim fractures and the predictions produced both rim and tooth fractures, depending on the initial geometry of the crack.

Descriptors :   *COMPUTER PROGRAMS, *THICKNESS, *FINITE ELEMENT ANALYSIS, *CRACK PROPAGATION, *COMPUTER AIDED DIAGNOSIS, *GEAR TEETH, STRESSES, EXPERIMENTAL DATA, AUTOMATION, PREDICTIONS, CRACKS, ELASTIC PROPERTIES, TEST METHODS, BENDING, FRACTURE(MECHANICS), CODING, LINEARITY, GEOMETRY, HEIGHT, GEARS, FATIGUE TESTS(MECHANICS).

Subject Categories : Numerical Mathematics
      Computer Programming and Software
      Machinery and Tools
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE