Fretting Fatigue Life Analysis And Calculation Of Wind Power Planet Carrier

Fretting fatigue often occurs in contact components with relative small slippage, which is very common in engineering facts. When there are the bolt connection, riveting as well as interference connection, the contact surfaces are prone to fretting, which easily leads to fretting fatigue damage. Fretting fatigue will greatly reduce the service life of components, so we must pay special attention to this part during the design.Wind power generation planet carrier and the flange connecting structure is designed with interference connection, and the finite element analysis shows that the both ends of contact surface in interference fit have slipped slightly. In order to ensure the service life of the planet carrier, we need to make a fretting fatigue analysis on the interference junction of planet carrier and flange, and then calculate the fretting fatigue life. Firstly, we must find out the location of fretting slippage and confirm the most dangerous section according to corresponding pressure distributions of the contact surface. Secondly, estimate the crack initiation through the stress singularity line parameters according to the stress distribution of the central path on the interface singular stress field. Thirdly, analyze the mechanism of fretting fatigue damage and choose the most dangerous loading sequence. Finally, this paper will calculation the fretting wear amount and amend the finite element model by establishing two models imposing the amount of wear gradually or directly exerting the maximum amount of wear, On this basis, we can obtain contact and frictional stress distributions of the contact section respectively. Then we will find the range of stress intensity factor and determine the crack propagation by comparing stress intensity factor range with material’s threshold stress intensity factor range. Through comparing calculations by imposing two different wear amounts, we can obtain fatigue crack propagation under actual loads.When using the most dangerous loading order as the actual load order and under the condition of imposing wear gradually or directly exerting the maximum wear amount, wear crack will stop the expansion until it was extended to279μm and300.4μm. The calculation shows that crack length of directly exerting the wear amount is longer, while the result of this method is conservative. The final calculation result also shows the fretting fatigue life of the planet carrier can meet the design requirements.