The Theoretical And Experimental Research On Static And Dynamic Characteristics Of Defective Porous Aerostatic Bearing

Porous aerostatic bearings are widely used in the measurement equipment,aerospace,optical devices and other high-precision fields because of their uniform pressure distribution,high bearing capacity and stiffness,high stability and good damping performance.During the installation or operation of porous aerostatic bearing,the scratch on the bearing surface caused by improper operation or overturning of the bearing,and the blockage of porous material caused by unclean gas supply source often occur.But at present,there is no systematic classification and Research on the defect forms and the performance effects caused by the defects in the installation and work of porous gas bearings at home and abroad.Therefore,in order to ensure that the bearing can still meet the working requirements in the presence of defects,it is necessary to systematically study the influence of defects on the bearing performance.In this paper,the disc-shaped hydrostatic porous bearing is taken as the research object,the possible defects are summarized and classified,and the influence of defects on the static and dynamic performance of aerostatic porous bearing is studied through simulation and experiment.Based on the three-dimensional capillary model,the gas flow model at the gas film gap is simplified to a porous gas flow model with infinite permeability,so as to solve the technical problem of complex iteration of existing methods for calculating defective porous bearings.The finite difference method and Newton iteration method are used to simulate the static performance of porous gas bearing with defects,and the influence of different types and distribution of defects on the pressure distribution,bearing capacity and static stiffness of gas film gap is analyzed.The small disturbance method is used to simulate the dynamic performance of the bearing,and the influence of different defect types and distribution on the dynamic stiffness and static damping of the bearing is studied.The static and dynamic characteristic test bech of hydrostatic bearing is used to study the pressure distribution,load-carrying capacity and vibration characteristics of typical defective bearing.The theoretical analysis and experimental results show that under the same defect size,the adverse effect of scratch defect on the static performance of bearing is greater than that of blocking defect,but the adverse effect of blocking defect on the dynamic performance of bearing is greater than that of scratch defect.The influence of circumferential or uniform distribution defects on bearing performance is less than that of radial or local distribution defects.The influence of defect size and location on bearing performance is greater than the number of defects.The research results of this paper provide a basis for judging whether the porous aerostatic bearing can meet the performance requirements in the case of defects.