The static strength theory applied in the design process of the planetary reducer can’t reflect the dynamic loads suffered by it

so the faults of the planetary reducer are more than the imagination in running process.In order to solve the problem basically

the most important thing is the dynamic loads.The dynamic simulation of the planetary reducer based on running simulation is carried out

and the dynamic loads in different profile of the planetary reducer are obtained.By fatigue damage cumulative theory

the reason of damage under the working loads much lower than design loads is explained.The process of obtaining dynamic loads with the example of planetary frame in different profile is demonstrated.Important reference data of fatigue design and life prediction for planetary reducer are provided.