Spur Gear Tooth Root Critical Section

The location of spur gear maximum tooth root stress determined by the use of 3D FEM, is compared with the corresponding stress locations according to analytical methods for nominal tooth root stress calculation that define critical tooth root section differently. The first tooth root stress calculation procedure is method B proposed by the standard ISO, and second one is modified version of it, called method MAX. Unlike the assumed uniform tooth root stress distribution along the tooth face for 2D approach of stress calculation, the analysis of stress based upon the 3D FEM calculation has proved considerable stress variation along the tooth face width for a solid and thin-rimmed gear, and the dependence of maximum tooth root stress location upon the rim thickness.