Low-temperature Property And Fatigue Resistant Researches On Planet Carrier Casting Steel Of Wind Turbine Gearbox

The wind turbine gearbox planet carrier is an important structure of wind turbine.Since the wind turbine is generally located in the remote land or sea,there is the bad working status such as the impact of wind and low temperature.Planet carrier is made up of cast steel materials.Mechanical properties in low temperature and fatigue resistance of materials are important indicators for safety and service life.With the improvement of demand in new energy,the wind fields have been developed and built on a large scale.Considering the challenges above,it is of great theoretical and practical value to research the low temperatur e mechanical properties and fatigue resistance of wind turbine gearbox planet carrier.Based on the structure of wind turbine gearbox and the features of planet carrier,the three-dimensional modeling and force analysis are carried out.On this basis,the finite element simulation analysis shows the part of planet carrier which is easy to produce fatigue damage.Before the study of mechanical properties of low temperature,the basic mechanical properties of the planet carrier cast steel samples are obtained by normal temperature tensile test.Then,considering the impact of wind in low temperature,the regular of the impact energy with temperature is obtained by using “Charpy” impact test,in which V-notched and U-notched impact test in normal and low temperatures are studied.The shape of impact fracture was observed by scanning electron microscope(SEM),and the relationship between fracture feature and fracture mechanism was analyzed.Then,anti-fatigue performance of wind turbine gearbox planet carrier is studied.The fatigue test was carried out by using the high frequency fatigue testing machine,the stress-fatigue life(S-N)curve and the fatigue limit of the material were obtain by data processing.In addition,the morphology of the typical fatigue fracture of the fatigue strip was observed by SEM.For further study,the fatigue crack propagation test of the standard compact tensile C(T)specimen was carried out by using the MTS test system machine.The plane strain fracture toughness,which characterized the capability of resist crack instability propagation is obtained.The P-V curve corresponding to the load P and the crack opening displacement V is obtained.Through the calculation and judgment,the value of fracture toughness between different sampling directions was comparatively analyzed.The shape of fatigue fracture was observed by SEM,and the fracture mechanism of the material was analyzed.