According to the calculation results, the curve of bending P-S-N of two different process gears of 20crnimoh material is shown in Fig. 1 and Fig. 2, and the curve of S-N of 50% survival rate of two different process gears is shown in Fig. 3.
The power functions of the curves of different survival rates of shot peened gears are as follows.
a. When p = 50%, S-N curve formula is s = 2392.1n-0.075 (r = 0.9569);
b. When p = 90%, S-N curve formula is s = 2458.5n-0.081 (r = 0.9495);
c. When p = 95%, S-N curve formula is s = 2460.4n-0.082 (r = 0.9436);
d. When p = 99%, S-N curve formula is s = 2450.3n-0.083 (r = 0.9289).
The curve formula of different survival rate of non shot peened gear is as follows.
a. When p = 50%, S-N curve formula is s = 1982.9n-0.077 (r = 0.9989);
b. When p = 90%, S-N curve formula is s = 2012.1n-0.08 (r = 0.999 6);
c. When p = 95%, S-N curve formula is s = 2017.2.4n-0.081 (r = 0.999 7);
d. When p = 99%, S-N curve formula is s = 2026.4n-0.083 (r = 0.999 7).