基于库伦摩擦效应的箔片轴承极限承载力理论与试验

Theory and experiment of foil bearing limiting load capacity based on Coulomb friction effect

基于有限单元法建立了考虑库伦摩擦的波箔型径向气体箔片轴承的箔片结构模型,采用有限差分法和有限单元法耦合求解Reynolds方程和气膜厚度方程,通过求解轴颈达到极限偏心率时的轴承极限承载力,研究了箔片结构库伦摩擦效应对轴承极限承载力的影响规律,并搭建了轴承极限承载力测试试验台,利用温度法测量了两个具有不同轴承壳内表面粗糙度的波箔型径向气体箔片轴承的轴承极限承载力.通过对比分析仿真结果与试验结果表明:轴承壳圆柱孔内表面粗糙度为0.4μm的轴承在10000r/min和20000r/min下,轴承极限承载力分别为15.5N和42.3N;而表面粗糙度为1.6μm的轴承极限承载力为10.9N和29.6N,这是由于波纹箔片和轴承壳体之间的库伦摩擦力增大了波纹箔片的刚度,因此增大箔片结构摩擦因数使得轴承极限承载力降低,并且仿真结果变化趋势和试验结果变化趋势吻合.

The foil structural finite element model of bump-type gas foil journal bearing was developed in consideration of Coulomb friction in foil structure. The compressible gas lubricated Reynolds equation and the film thickness equation were solved together by using finite element method and finite difference method. The Coulomb friction effect on bearing limiting load capacity were studied when the journal eccentricity reached the limit. The test bed was established to test the limiting load capacity for two bump-type gas foil journal bear ings with different roughness of bearing housing cylindrical hole surface by using tempera ture method. The numerical and experimental results were compared, indicating that the bearing limiting load capacities with roughness of bearing housing cylindrical hole surface 0.4 um at speed 10 000 r/rain and 20 000 r/rain are 15.5 N and 42.3 N respectively, while the bearing limiting load capacities with roughness 1.6um are 10. 9N and 29. 6N respectively. The bearing limiting load capacity decreases with the increasing of roughness of bearing housing cylindrical hole surface due to the enhanced stiffness of bump foil caused by Coulombfriction force in foil structure, and the trend of numerical results agrees well with the experi mental results.