Load stresses and residual stresses in the tooth interior

Designing gears against tooth interior fatigue fracture requires basic knowledge of local stress states. Therefore an analytical model enabling to determine the interior load stresses during meshing of gears has been developed and is validated through comparisons with FE-simulations revealing a good compliance. Besides load stresses residual stresses play an important role in tooth interior fatigue. However, many residual stress measurement methods have small penetration depths. In contrast the Contour Method (1, 2) allows measuring a 2-D map of interior residual stresses as demonstrated for a case hardened test gear. The obtained residual stresses agree with depth-corrected X-ray measurements.