风电主轴双支承圆锥滚子轴承疲劳寿命计算

Fatigue Life Calculation of Tapered Roller Bearings for Doubly Supporting Wind Turbine Main Shaft

针对直驱式风电机组主轴双支承圆锥滚子轴承组合,建立了一种轴承疲劳寿命理论计算方法。首先,在笛卡尔坐标系中对轴承滚道进行数学描述;其次,运用坐标变换原理建立滚子-滚道接触变形与套圈位移之间的数学关系,借助于变形协调条件和受力平衡条件解决滚子载荷分布的静不定求解问题,通过对模型的数值求解得到轴承内部每个滚子的载荷;然后,运用有限长线接触理论建立修形滚子与套圈滚道之间的弹性接触模型,计算得到滚子与滚道之间的接触应力分布和滚道边缘应力修正函数;最后,通过边缘应力修正函数修正当量滚子切片载荷,进而准确计算轴承疲劳寿命。实例分析结果表明:滚子素线修形量对滚子与滚道之间的接触应力分布和轴承疲劳寿命有显著影响,轴承疲劳寿命随滚子凸度系数增大先急剧上升,达到最大值后缓慢下降。

For the combination of single row tapered roller bearings for doubly supporting direct-driven wind turbine main shaft,a theoretical calculation method is established for fatigue life of the bearings.Firstly,the bearing raceway is described mathematically in Cartesian coordinate system.Secondly,the mathematical relationship between roller-racewoy contact deformation and ring displacement is established by using coordinate transformation principle,the statically indeterminate solution problem of roller load distribution is solved by means of deformation compatibility coordination condition and force balance condition,and the load of each roller in the bearings is obtained by numerical solution of model.Then,the elastic contact model between profiled roller and ring raceway is established by using finite length line contact theory,the contact stress distribution between roller and raceway and edge stress correction function of raceway are calculated.Finally,the fatigue life of the bearings are accurately calculated by modifying the equivalent roller slice load with edge stress correction function.The results of case analysis indicate that the profiled quantity of roller generatrix has a significant effect on contact stress distribution between roller and raceway and fatigue life of the bearings,the fatigue life of the bearings first increases sharply with the increase of crowning coefficient of roller,and then decreases slowly after reaching the maximum.