Comparison of S-N curves between international standard ISO / TS 6336-2 and American Standard an-si / AGMA 2001-d04

Put the two standard S-N curves together, the abscissa is the number of stress cycles, the ordinate is the contact stress of gear, and the comparison curve is shown in the figure.

According to the S-N curve comparison results of the two standards, the international standard ISO / TS 6336-2 is 105 in the dead load area, while the American standard is 104 in the dead load area, compared with the American Standard ANSI / AGMA 2001-d04; in the limited life area, the international standard is 3 × 107, while the American standard is 1 × 107. Moreover, the slope of the S-N curve of the international standard is larger than that of the American Standard, which indicates that with the increase of the load in this region, the contact life of the American Standard gear will decrease more than that of the international standard, which will be proved in the later calculation; in the long life region, the sequential termination limit of the two standards is 1 × 1010, and there is only a small difference between the S-N curves.

It should be emphasized that the S-N curves of the two standards are different, and the calculation methods of contact stress are also different. The calculation of contact life of gears should be carried out under the same standard system, otherwise it will get wrong verification