多孔质气体止推轴承跨缝过程时变特性研究

Research on Time-Variant Characteristics of Porous Aerostatic Thrust Bearing in the Process of Cross Slot of Air Supportive Stage

针对某大型超平气浮支撑平台上卫星模拟器所使用的多孔质气体止推轴承,在跨越气浮平台的拼缝过程中存在的运动卡滞和自激振动问题,建立多孔质轴承气体润滑理论模型,考察气体轴承的稳态特性;使用有限元法分析多孔质气体轴承通过拼缝时的动态时变特性,并分析压力分布、承载能力、倾覆力矩的变化。结果表明:平台拼缝间隙的存在对多孔质气体止推轴承压力分布造成了较大的影响,导致跨缝过程中其承载能力大幅降低,从而造成轴承表面划伤,因此在轴承的设计选用中应留有较多的承载余量;多孔质气体止推轴承在跨峰过程中,在其运动方向上存在呈正弦波动的倾覆力矩,但对其正常使用不会造成影响。

In view of the problems of motion stagnation and self-excited vibration for the porous aerostatic thrust bearing used in the large super-smooth supportive stage for lunar orbit rendezvous and docking tests when going through the slot of air supportive stage,a theoretical model of the porous aerostatic thrust bearing was built according to gas lubrication theory,and the steady state characteristics of the bearing were studied.The dynamic time-variant characteristics when the bearing goes through the slot of air supportive stage were analyzed by the finite element method,and the variation of pressure distribution,carrying capacity and overturning moment were also analyzed.The results show that the existence of the slot of air supportive stage has a great influence on the pressure distribution of the porous aerostatic thrust bearing,which leads to the great reduction of the bearing capacity of the porous aerostatic thrust bearing in the process of cross slot,thus causing the bearing surface scratch.Therefore,more bearing allowance should be given in the design and selection of the bearing.The overturning moment of the porous aerostatic thrust bearing is fluctuated sinusoidally in the motion direction,but it will not affect the normal use of the porous aerostatic thrust bearing.