Tooth Bending Strength in the VHCF Area

Abstract

Abstract The use of gears in electrified drivetrains and aircraft turbines leads to higher operating speeds and a higher number of load cycles at the pinion. Load cycles of N > 107 in the Very High Cycle Fatigue (VHCF) area cause a decrease in the endurance strength of case-hardened steels. Furthermore, increasing speeds increase the strain rate in the tooth root, which also has an influence on the fatigue strength known from standard tests. The determination of the strain rate effect requires the evaluation of the test results regarding the statistical significance. The aim of this report is to analyze the different influencing factors on the tooth bending strength, e.g. contour of the tooth root, gear quality, roughness etc. Test gears are measured and the results are traced back to a FE-based tooth contact analysis for the calculation of the tooth root stress. Furthermore, the uncertainties coming for the testing procedure (e.g. stair case or horizon method) are examined and the most appropriate procedure for the planned tests is selected. In the last step the tooth bending strength in the VHCF area is tested on a 3-shaft back-to-back test rig. The test results are evaluated regarding the failure mechanisms and the statistical behavior. Finally, the minimum number of tests regarding the statistical significance of the results is assessed.

Authors 4

1. Moritz Zalfen Aachen

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University , Aachen, Germany

2. Dieter Mevissen Aachen

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University , Aachen, Germany

3. Jens Brimmers Aachen

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University , Aachen, Germany

4. Christian Brecher Aachen

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University , Aachen, Germany