Calculation and Simulation Azimuth Hydrostatic Thrust Bearing of a Large Alt-Azimuth Telescope

2013 ◽  
Vol 364 ◽  
pp. 28-32
Author(s):  
Long Huang ◽  
Wen Li Ma ◽  
Jin Long Huang
Keyword(s):  
Thrust Bearing ◽  
Structure Parameter ◽  
Tracking Accuracy ◽  
Low Friction ◽  
Element Analysis ◽  
Hydrostatic Bearing ◽  
Wide Range ◽  
And Performance ◽  
Large Telescopes ◽  
Main Factor

The use of hydrostatic bearing for support of telescope offers a number of potential performance advantages, but the structure parameter of bearing is the main factor which influence the bearing. The temperature rise of bearing is also important for the stiffnees of the telescope mount.In addition to the known benefit of mount stiffness and tracking accuracy from exceedingly low friction, the hydrostatic bearing provides a wide range of geometric possibilities for large telescopes [1].This paper analyzes various familiar hydrostatic bearing for the azimuth and elevation axes of telescope.Theoretical calculation and simulation show that the performance of bearing meets telescope’s design requirements.The principle and process of this work and Finite Element Analysis (FEA) are introduced in detail. According to the CFX result, the structure parameter and performance of bearing ,temperature field and pressure distribution have obtained.

Static Characteristics of a Rectangular Hydrostatic Thrust Bearing With a Self-Controlled Restrictor Employing a Floating Disk

1993 ◽  
Vol 115 (2) ◽  
pp. 307-311 ◽  
Author(s):  
S. Yoshimoto ◽  
Y. Anno ◽  
M. Fujimura
Keyword(s):  
Flow Rate ◽  
Applied Load ◽  
Thrust Bearing ◽  
Static Characteristics ◽  
Hydrostatic Bearing ◽  
Supply Pressure ◽  
Wide Range ◽  
Bearing Stiffness ◽  
New Type ◽  
Very High

This paper proposes a new type of a self-controlled restrictor which can achieve a very high bearing stiffness in hydrostatic bearings. This self-controlled restrictor employs a floating disk to control the mass flow rate of the oil entering the bearing clearance according to changes of the applied load. Furthermore, a hydrostatic bearing with this restrictor can theoretically achieve an infinite stiffness when the mass of a floating disk is assumed to be zero. The static characteristics of a rectangular hydrostatic thrust bearing with this self-controlled restrictor are theoretically and experimentally investigated. It was consequently shown that the proposed hydrostatic thrust bearing can achieve a very high stiffness (nearly infinite stiffness) in a very wide range of applied load independent of supply pressure.

Finite Element Analysis of Thrust Bearing Magnetic Field in 22KW Spindle

2008 ◽  
Vol 392-394 ◽  
pp. 761-766 ◽  
Author(s):  
G.Q. Wu ◽  
J.L. Zhou ◽  
Xu Dong Zhang ◽  
Y.M. Zhang ◽  
Xiao Ni Chi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Finite Element ◽  
Thrust Bearing ◽  
System Structure ◽  
Magnetic Saturation ◽  
Element Analysis ◽  
Direction Control ◽  
And Performance ◽  
The Magnetic Field ◽  
Flux Leakage

There is a magnetic field inside thrust bearing. The magnetic field distribution is one of the key factors which decide the running state and performance. With the finite element of ANSYS software, the magnetic field of thrust bearing has been analyzed. The rule of changes between the magnetic field and the influencing factors has been discovered. The analysis shows that the direction of exciting current should be opposite other than identical. The greater the ratio of gap length between stator and rotor and working gap length is, the less magnetic field leakage is. The flux leakage of thrust bearing attains 37 percent when the ratio of the gap is 4.0. If the design of a complete machine is not proper, the flux leakage may attain 20 percent upwards through other gaps although that of the bearing itself is almost zero. Calculation of bearing capacity indicates that theoretical value is not exact due to its neglect of magnetic saturation and flux leakage, while FEM value comparably matches the real substance with considering the magnetic saturation and flux leakage. The research provides the theoretical basis for optimization of system structure and selection of current direction control.

scholarly journals Analysis, Design, and Testing of a Low Profile Deflection Pad™ Thrust Bearing in an Industrial Gas Turbine

1994 ◽  
Author(s):  
Dilip Jain ◽  
Fouad Zeidan ◽  
Michael Wittmeyer
Keyword(s):  
Gas Turbine ◽  
Thrust Bearing ◽  
Element Analysis ◽  
Low Profile ◽  
Wide Range ◽  
Analysis Design ◽  
Thrust Pad ◽  
Industrial Gas Turbine ◽  
Design And Testing ◽  
Thrust Load

This paper describes the analysis, design, and testing of a low profile thrust bearing in a DR 990 industrial gas turbine. High unit loads and speeds, and the need to maintain low frictional power loss presented many challenges. The thrust pad design utilizes a flexure pivot, which allow near optimum performance for a wide range of speeds and loads in comparison to a fixed geometry taper land design. The use of high conductivity material for the thrust pads and directed lubrication allowed operation at lower temperatures. Finite element analysis was used to model the pad structure and pivot support. This analysis was confirmed by measuring the pad tilt using an eddy current probe. The test was conducted in a controlled thrust rig allowing accurate application and measurement of the thrust load. Precision manufacturing of the spherical seat and the application of a proprietary coating allowed better aligning capability under load. The bearing was tested in an engine at a range of speeds and loading conditions. The results are presented and compared with the existing fixed geometry bearing design. The bearing is currently running in an engine in the field and has accumulated 2,400 hours of operation with no forced outages.

scholarly journals Numerical Simulation and Experimental Study of the Hydrostatic Spindle with Orifice Restrictors

2016 ◽  
Vol 10 (1) ◽  
pp. 79-92
Author(s):  
He Qiang ◽  
Li Lili ◽  
Ren Fengzhang ◽  
Volinsky Alex
Keyword(s):  
Thrust Bearing ◽  
Rotation Speed ◽  
Cold Drawing ◽  
Rolling Bearings ◽  
Element Analysis ◽  
Rotating Speed ◽  
Hydrostatic Bearing ◽  
Fluid Flow Velocity ◽  
Hydrostatic Bearings ◽  
The Finite Element Analysis

Based on the theory of hydrostatic bearings, this paper presents a study of replacing the rolling bearings in a cold drawing spindle with the liquid hydrostatic bearings. An unloading mechanism is designed, containing two hydrostatic radial bearings and a thrust bearing, according to the mechanical characteristics of the spindle. In this study, a mathematical model of the hydrostatic bearing oil pad is developed. The effects of the rotating speed on pressure and flow fields of the oil pad are simulated using the finite element analysis and verified experimentally. The pressure in all recesses decreases with the rotation speed. Oil velocity of the radial hydrostatic bearing recess increases with the rotation speed, while the fluid flow velocity has almost no correlation with the rotation speed of the thrust bearing. The numerical and experimental results of the pressure in the recesses are consistent, confirming the validity and feasibility of this design.

Analysis of organic removal rates in the aerated submerged fixed film process

1998 ◽  
Vol 38 (8-9) ◽  
pp. 213-221 ◽  
Author(s):  
Mohamed F. Hamoda ◽  
Ibrahim A. Al-Ghusain
Keyword(s):  
Pilot Plant ◽  
Removal Rate ◽  
Domestic Wastewater ◽  
Removal Rates ◽  
Hydraulic Loading ◽  
Organic Removal ◽  
Wide Range ◽  
Fixed Film ◽  
Cod Removal Rate ◽  
And Performance

Performance data from a pilot-plant employing the four-stage aerated submerged fixed film (ASFF) process treating domestic wastewater were analyzed to examine the organic removal rates. The process has shown high BOD removal efficiencies (> 90%) over a wide range of hydraulic loading rates (0.04 to 0.68 m3/m2·d). It could also cope with high hydraulic and organic loadings with minimal loss in efficiency due to the large amount of immobilized biomass attained. The organic (BOD and COD) removal rate was influenced by the hydraulic loadings applied, but organic removal rates of up to 104 kg BOD/ m2·d were obtained at a hydraulic loading rate of 0.68 m3/m2·d. A Semi-empirical model for the bio-oxidation of organics in the ASFF process has been formulated and rate constants were calculated based on statistical analysis of pilot-plant data. The relationships obtained are very useful for analyzing the design and performance of the ASFF process and a variety of attached growth processes.

scholarly journals Friction of Metals: A Review of Microstructural Evolution and Nanoscale Phenomena in Shearing Contacts

2021 ◽  
Vol 69 (4) ◽  
Author(s):  
Michael Chandross ◽  
Nicolas Argibay
Keyword(s):  
Shear Strength ◽  
Grain Boundary Sliding ◽  
Deformation Mechanisms ◽  
Low Friction ◽  
Friction Behavior ◽  
Important Conclusion ◽  
Fundamental Properties ◽  
Wide Range ◽  
Boundary Sliding ◽  
Metal Interfaces

AbstractThe friction behavior of metals is directly linked to the mechanisms that accommodate deformation. We examine the links between mechanisms of strengthening, deformation, and the wide range of friction behaviors that are exhibited by shearing metal interfaces. Specifically, the focus is on understanding the shear strength of nanocrystalline and nanostructured metals, and conditions that lead to low friction coefficients. Grain boundary sliding and the breakdown of Hall–Petch strengthening at the shearing interface are found to generally and predictably explain the low friction of these materials. While the following is meant to serve as a general discussion of the strength of metals in the context of tribological applications, one important conclusion is that tribological research methods also provide opportunities for probing the fundamental properties and deformation mechanisms of metals.

scholarly journals Constructing a biomimetic robust bi-layered hydrophilic lubrication coating on surface of silicone elastomer

Friction ◽  
2021 ◽  
Author(s):  
Luyao Gao ◽  
Xiaoduo Zhao ◽  
Shuanhong Ma ◽  
Zhengfeng Ma ◽  
Meirong Cai ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Composite Layer ◽  
High Load ◽  
Silicone Elastomer ◽  
Aqueous Lubrication ◽  
Low Friction ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Lubrication Performance ◽  
Wide Range

AbstractSilicone elastomers-based materials have been extensively involved in the field of biomedical devices, while their use is extremely restricted due to the poor surface lubricity and inherent hydrophobicity. This paper describes a novel strategy for generating a robust layered soft matter lubrication coating on the surface of the polydimethylsiloxane (PDMS) silicone elastomer, by entangling thick polyzwitterionic polyelectrolyte brush of poly (sulfobetaine methacrylate) (PSBMA) into the sub-surface of the initiator-embedded stiff hydrogel coating layer of P(AAm-co-AA-co-HEMA-Br)/Fe, to achieve a unified low friction and high load-bearing properties. Meanwhile, the stiff hydrogel layer with controllable thickness is covalently anchored on the surface of PDMS by adding iron powder to provide catalytic sites through surface catalytically initiated radical polymerization (SCIRP) method and provides high load-bearing capacity, while the topmost brush/hydrogel composite layer is highly effective for aqueous lubrication. Their synergy effects are capable of attaining low friction coefficient (COFs) under wide range of loaded condition in water environment with steel ball as sliding pair. Furthermore, the influence of mechanical modulus of the stiff hydrogel layer on the lubrication performance of layered coating is investigated, for which the COF is the lowest only when the modulus of the stiff hydrogel layer well matches the PDMS substrate. Surprisingly, the COF of the modified PDMS could remain low friction (COF < 0.05) stably after encountering 50,000 sliding cycles under 10 N load. Finally, the surface wear characterizations prove the robustness of the layered lubricating coating. This work provides a new route for engineering lubricious silicon elastomer with low friction, high load-bearing capacity, and considerable durability.

scholarly journals Fabrication and Compressive Behavior of a Micro-Lattice Composite by High Resolution DLP Stereolithography

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 785
Author(s):  
Chow Shing Shin ◽  
Yu Chia Chang
Keyword(s):  
High Resolution ◽  
Lattice Structure ◽  
Low Cost ◽  
Hierarchical Structures ◽  
Dip Coating ◽  
Unit Cell ◽  
Digital Light Processing ◽  
Unit Cell Size ◽  
Wide Range ◽  
And Performance

Lattice structures are superior to stochastic foams in mechanical properties and are finding increasing applications. Their properties can be tailored in a wide range through adjusting the design and dimensions of the unit cell, changing the constituent materials as well as forming into hierarchical structures. In order to achieve more levels of hierarchy, the dimensions of the fundamental lattice have to be small enough. Although lattice size of several microns can be fabricated using the two-photon polymerization technique, sophisticated and costly equipment is required. To balance cost and performance, a low-cost high resolution micro-stereolithographic system has been developed in this work based on a commercial digital light processing (DLP) projector. Unit cell lengths as small as 100 μm have been successfully fabricated. Decreasing the unit cell size from 150 to 100 μm increased the compressive stiffness by 26%. Different pretreatments to facilitate the electroless plating of nickel on the lattice structure have been attempted. A pretreatment of dip coating in a graphene suspension is the most successful and increased the strength and stiffness by 5.3 and 3.6 times, respectively. Even a very light and incomplete nickel plating in the interior has increase the structural stiffness and strength by more than twofold.

scholarly journals Design of 3D Additively Manufactured Hybrid Structures for Cranioplasty

Materials ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 181
Author(s):  
Roberto De Santis ◽  
Teresa Russo ◽  
Julietta V. Rau ◽  
Ida Papallo ◽  
Massimo Martorelli ◽  
...  
Keyword(s):  
Physical Models ◽  
Cranial Bone ◽  
Head Model ◽  
Rigid Sphere ◽  
Element Analysis ◽  
Aliphatic Polyesters ◽  
Hybrid Device ◽  
Wide Range ◽  
Hybrid Devices ◽  
Technical Solutions

A wide range of materials has been considered to repair cranial defects. In the field of cranioplasty, poly(methyl methacrylate) (PMMA)-based bone cements and modifications through the inclusion of copper doped tricalcium phosphate (Cu-TCP) particles have been already investigated. On the other hand, aliphatic polyesters such as poly(ε-caprolactone) (PCL) and polylactic acid (PLA) have been frequently investigated to make scaffolds for cranial bone regeneration. Accordingly, the aim of the current research was to design and fabricate customized hybrid devices for the repair of large cranial defects integrating the reverse engineering approach with additive manufacturing, The hybrid device consisted of a 3D additive manufactured polyester porous structures infiltrated with PMMA/Cu-TCP (97.5/2.5 w/w) bone cement. Temperature profiles were first evaluated for 3D hybrid devices (PCL/PMMA, PLA/PMMA, PCL/PMMA/Cu-TCP and PLA/PMMA/Cu-TCP). Peak temperatures recorded for hybrid PCL/PMMA and PCL/PMMA/Cu-TCP were significantly lower than those found for the PLA-based ones. Virtual and physical models of customized devices for large cranial defect were developed to assess the feasibility of the proposed technical solutions. A theoretical analysis was preliminarily performed on the entire head model trying to simulate severe impact conditions for people with the customized hybrid device (PCL/PMMA/Cu-TCP) (i.e., a rigid sphere impacting the implant region of the head). Results from finite element analysis (FEA) provided information on the different components of the model.

Improvement of the Detection Sensitivity of Edxrf Trace Element Analysis by Means of Efficient X-Ray Focusing Based on Strongly Curved Hopg Crystals

1995 ◽  
Vol 39 ◽  
pp. 109-117
Author(s):  
Burkhard Beckhoff ◽  
Birgit Kanngießer
Keyword(s):  
High Intensity ◽  
Focal Plane ◽  
Bragg Reflection ◽  
Pyrolytic Graphite ◽  
Trace Element Analysis ◽  
Detection Sensitivity ◽  
Element Analysis ◽  
X Ray ◽  
Wide Range ◽  
Very High

X-ray focusing based on Bragg reflection at curved crystals allows collection of a large solid angle of incident radiation, monochromatization of this radiation, and condensation of the beam reflected at the crystal into a small spatial cross-section in a pre-selected focal plane. Thus, for the Bragg reflected radiation, one can achieve higher intensities than for the radiation passing directly to the same small area in the focal plane. In that case one can profit considerably from X-ray focusing in an EDXRF arrangement. The 00 2 reflection at Highly Oriented Pyrolytic Graphite (HOPG) crystals offers a very high intensity of the Bragg reflected beam for a wide range of photon energies. Furthermore, curvature radii smaller than 10 mm can be achieved for HOPG crystals ensuring efficient X-ray focusing in EDXRF applications. For the trace analysis of very small amounts of specimen material deposited on small areas of thin-filter backings, HOPG based X-ray focusing may be used to achieve a very high intensity of monochromatic excitation radiation.

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