Before carrying out the bending fatigue test, it is necessary to determine the stress level of the test. Two of the processed specimens are selected for static strength test. According to the static strength test, the highest stress level is σ F1=966.5MPa.

Four stress levels were selected for the bending fatigue test σ F1=966.5MPa， σ F2=805.4MPa， σ F3=644.3MPa， σ F4=429.5MPa。 The test gear and the teeth on the gear are numbered with numbers 01-18 respectively. Since the single tooth loading is used in the test, it is necessary to apply the force on the teeth pressed by the upper indenter and the teeth supported by the lower indenter, and retract the teeth pressed by the upper indenter and the teeth pressed by the lower indenter with two teeth between them. During the test, it must be ensured that the connecting line of the center line of the upper and lower indenters is tangent to the base circle.

The test is divided into four groups, six test points in each group, the specific situation is: 45 kn test, take six test points; The test of 37 kn was carried out and 6 test points were selected; Carry out the test of 30 kn, take 6 test points; The test of 20 kn was carried out and 6 test points were selected.

During the test, check the condition of the compressed teeth every 30 minutes, and record the average load, maximum load, minimum load, maximum current, vibration frequency, excitation power and cycle times. The appearance of gear fatigue is judged by the measured crack, frequency and load condition. When the measured crack, frequency and load decrease more than 5% of the initial value, it can be considered as crack.

When the number of cycles is more than 10000000, if the gear is still not damaged, it is judged that the test point is the overrun point and the loading is stopped.

The normal distribution of the test points corresponding to the four stress levels is detected. If the correlation coefficient of the distribution function can not meet the corresponding requirements, the test of the stress level is continued to obtain qualified supplementary points until the requirements are met.