Tooth Root Crack Propagation: A Method to Convert Pulsator Experimental Lifetime to Meshing Conditions

Pulsator tests are used to characterize the bending fatigue strength of the tooth root. In these tests, the tooth root is loaded not by meshing with another gear but by applying a pulsating load to the tooth flank via a testing machine. This leads to a different S-N curve with respect to the ones obtained through meshing gear tests. This study aims to investigate the impact of cracks in the tooth root on the results of pulsator and meshing tests. Here, we address the issue of load sharing modification during meshing due to the presence of a crack, and its influence on crack propagation. This approach is applied to a real-life example: estimating the finite life of meshing gears based on pulsator tests. This study aims to present an initial procedure for obtaining S-N curves for meshing gears based on those obtained from pulsator tests. The S-N curves obtained from the pulsator test are compensated for by adding the difference in the propagation speed between the two tests calculated by applying the Paris law with parameters extracted from FE simulation; the time spent in propagation is almost doubled in the meshing conditions.