Motion errors of hydrostatic guideways are mainly influenced by the geometric errors of guide rails and table which can be decomposed into harmonic waves of different frequencies based on Fourier transform. In this paper, a new approximate model is established to study the influence of geometric errors of guide rails and table on the motion errors of hydrostatic guideways using the equivalent third power of oil film thickness. It is found that, the motion errors are mainly affected by the geometric errors of guide rails rather than the geometric errors of table. The harmonic waves with wave numbers 0.5, 1.5, 2.5, 3.5, …, on the guide rails have no influence on the center displacement of table, and the harmonic waves with wave numbers 1, 2, 3, 4, …, have no influence on the yaw angle of table. The increment of land width and decrement of distance of two adjacent pads will result in enhancement of comprehensive averaging effect in consideration of center displacement and yaw angle. The approximate formulas have sufficient calculation accuracy compared with FEM when the ratio between amplitude of harmonic wave and initial film thickness is small. Using a deformed guide rail with wave numbers 0.5 and 1, the results of experiments agree well with the results calculated by approximate formulas and FEM. In the experiments, a novel method is proposed to manufacture the single harmonic wave of guide rail in the scale of micron meters, through which the amplitude and wavelength of the harmonic wave on guide rail can be controlled.

Influence of geometric errors of guide rails and table on motion errors of hydrostatic guideways under quasi-static condition

A self-compensating linear fluidstatic or hydrostatic bearing and method in which preferably circular annular pressurized-fluid-receiving grooves provided in the opposed carriage bearing surfaces regulate the fluid fed to longitudinal recess pockets formed in the opposing bearing surfaces to provide a thin film or layer of pressurized fluid in the gaps between a bearing rail and the opposing bearing surfaces; the regulation establishing differential pressures in the opposing bearing surface pockets to compensate for loads applied to opposite sides of the bearing.

Self-compensating hydrostatic linear motion bearing

Characteristics of multipad hydrostatic thrust bearings under rotation

Experimental tank testing is a key aspect of wave energy conversion research The performance of designs can be assessed in an accessible and controlled environment and at a fraction of the cost of sea trials Wave energy converter (WEC) tank testing is complex and has its own specificities compared with model testing of ships and offshore structures This largely reflects the fact that the main quantity of interest is wave energy: how much is available and how much is harvested by the model This paper provides an extensive overview of the various aspects of WEC tank testing These are divided into three categories: physical model, measurements, and wave generation For each of them, current best practice guidelines are given

/pdf/best-practice-guidelines-for-tank-testing-of-wave-energy-2faqw61f3o.pdf

Best practice guidelines for tank testing of wave energy converters

The present paper deals with a theoretical analysis of 4-pocket capillary compensated conical hybrid journal bearing system operating with micropolar lubricant. The modified Reynolds equation for a conical journal bearing system operating with micropolar lubricant has been derived. In the present study, Eringen's micropolar theory has been used to model micropolar lubrication in cylindrical coordinate system. The study has been carried out for the different values of micropolar parameters, that is, characteristic length () and coupling number (). The conical bearing configurations having semicone angle 10∘, 20∘, 30∘, and 40∘ have been studied. The study suggests that micropolar lubricant offers better performance vis- a-vis Newtonian lubricant for bearing configurations having values of semicone angle 10∘and 20∘.

/pdf/influence-of-micropolar-lubrication-on-the-performance-of-4-1xl83nazdr.pdf

Frank Melvin Stansfield

Papers

Hydrostatic bearings for machine tools and similar applications