Permissible exposure

Based on the maximum value for exposure, a statement can be made on whether a hazard exists for the component under the existing operating and heat management parameters. For damage well below the component surface (flank fracture), the exposure limit ,above which a risk of damage must be expected, is approximately 0.8 [1].

The exposure limit of 0.8 indirectly considers, for example, influences from inclusions, which according to tests from [2] can lead lo local stress increases, and is calibrated by experimental tests from multiple research projects as well as practical experience [1].

With more precise knowledge of the condition of the microstructure and the distribution of inclusions of the gear being considered, both of which do not directly influence the computational consideration according to the current state of knowledge, the exposure limit from which the risk of damage must be expected, may be modified [1].

[1] Witzig J.: Flank Breakage - A Limitation of the Gear Load Capacity Beyond the Material Depth. Dissertation TU Munich 2012
[2] SCHMIDT, W. Untersuchungen zur Grübchen- und zur Zahnfußtragfähigkeit geradverzahnter evolventischer Innenstirnräder. TU Munich 1984