Optical Analysis of Porous Metal Bearings

1979 ◽  
Vol 101 (1) ◽  
pp. 99-104 ◽  
Author(s):  
K. M. Yung ◽  
A. Cameron
Keyword(s):  
Thermal Expansion ◽  
Metal Particle ◽  
Porous Metal ◽  
Optical Interferometry ◽  
Approximate Analysis ◽  
Optical Analysis ◽  
Oil Film ◽  
Order Of Magnitude

Optical interferometry is used to study the lubrication of porous bearings. The results suggest that thermal expansion in each metal particle causes it to act as a miniature tapered land bearing. An approximate analysis gives an order of magnitude for the tilt. All the evidence is against the existence of a continuous oil film round the bearing when used normally, which hitherto is the accepted model for the operation of these bearings. Micro-recirculation of the oil was observed and the importance of running-in is discussed.

Study on the Influence of Deformation of the Slipper of Axial Piston Pump under High Pressure on Oil Film Structure

2014 ◽  
Vol 900 ◽  
pp. 734-737 ◽  
Author(s):  
Huai Chao Wu ◽  
Yun Liu Yu
Keyword(s):  
High Pressure ◽  
Film Structure ◽  
Piston Pump ◽  
Axial Piston Pump ◽  
Working Pressure ◽  
Element Analysis ◽  
Oil Film ◽  
The Finite Element Analysis ◽  
Order Of Magnitude ◽  
Axial Piston

The stress and strain of the slipper of 35 MPa high pressure axial piston pump are analyzed by the finite element analysis method, and the following facts are revealed: in spite of the fact that the slipper can satisfy the use requirement in the aspect of stress, whereas, in the aspect of strain, the deformation of the bottom of the slipper increases with the pressure increase, and the deformation of the slipper has reached the order of magnitude of the oil film thickness under 35 MPa working pressure. Therefore, when the slipper pair of 35 MPa high pressure axial piston pump is designed and its oil film performances are studied, the influence of deformation of the slipper on the oil film structure must be considered comprehensively. The results of this study can provide some guides for developing 35 MPa high pressure axial piston pump.

scholarly journals Irreversible Thermal Expansion of Replicated Aluminium Foam

2018 ◽  
Vol 24 (2) ◽  
pp. 156
Author(s):  
Arkady Finkelstein ◽  
Dmitry Husnullin
Keyword(s):  
Thermal Expansion ◽  
Oxide Film ◽  
Thermal Cycling ◽  
Metal Foam ◽  
Porous Metal ◽  
Extraction Process ◽  
Aluminium Foam ◽  
Expansion Process ◽  
Porous Part

There was found irreversible thermal expansion of large items made of the replicated aluminium foam during the extraction of soluble filler from Al-NaCl composite. Sources of the phenomena were investigated. The expansion is discovered to be caused by incomplete contraction of the porous metal due to oxidation of its internal porous surface during thermal cycling with air and water presence. Significant role of oxide film defects in the expansion process was exposed. There was gained information on dependencies of the irreversible thermal expansion on temperature of the extraction process and metal foam pore size. Measurements of the expansion dynamics showed its finite character. It was also noted that the expansion is limited by the thermal expansion coefficient of used alloy. Finally correction coefficients were obtained that, being applied to nominal sizes of a porous part, compensates the expansion.

scholarly journals Bi-Material Negative Thermal Expansion Inverted Trapezoid Lattice based on A Composite Rod

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3379 ◽  
Author(s):  
Weipeng Luo ◽  
Shuai Xue ◽  
Meng Zhang ◽  
Cun Zhao ◽  
Guoxi Li
Keyword(s):  
Finite Element ◽  
Thermal Expansion ◽  
Experimental Verification ◽  
Negative Thermal Expansion ◽  
Engineering Application ◽  
Vertical Direction ◽  
Aerospace Engineering ◽  
Large Temperature ◽  
Composite Rod ◽  
Order Of Magnitude

Negative thermal expansion (NTE) lattices are widely used in aerospace engineering where the structures experience large temperature variation. However, the available range of NTE of the current lattices is quite narrow, which severely limits their engineering application. In this paper, we report an inverted trapezoid lattice (ITL) with large NTE. The NTE of the ITL is 2.6 times that of a typical triangular lattice with the same height and hypotenuse angle. Theoretically, with a pin-jointed assumption, the ITL can improve the NTE by order of magnitude if the length ratio of the composite rod is changed. In the presented ITL, a composite rod is utilized as the base of the ITL. The composite rod has large inner NTE. The inverted trapezoid structure converts the inner NTE to the vertical direction contraction and obtains an extra NTE. Finite element simulations and experimental verification by interferometric measurement were conducted to verify the large thermal expansion of the ITL.

Oil Film Thickness in Lightly-Loaded Roller Bearings

1974 ◽  
Vol 16 (6) ◽  
pp. 386-390 ◽  
Author(s):  
H. Bahadoran ◽  
R. Gohar
Keyword(s):  
Film Thickness ◽  
Similar Condition ◽  
Thrust Bearing ◽  
Roller Bearing ◽  
Optical Interferometry ◽  
Oil Film ◽  
Roller Bearings ◽  
Tapered Roller

The effects of speed, load and roller geometry on the oil film thickness and shape in a complete roller bearing are demonstrated experimentally by means of optical interferometry. At quite moderate roller speeds, increase of film thickness becomes inhibited. This effect is attributed to a truncated inlet meniscus, a similar condition having been observed elsewhere with a ball-and-plate machine and with a model of a tapered-roller thrust bearing.

Optical Measurement of EHL Film under Oscillating Needle Roller Contacts

2015 ◽  
Vol 642 ◽  
pp. 270-274
Author(s):  
Xue Jin Shen ◽  
Zhen Min Song ◽  
Xiao Yang Chen
Keyword(s):  
Film Thickness ◽  
Working Conditions ◽  
Applied Load ◽  
Optical Measurement ◽  
Rotation Velocity ◽  
Optical Interferometry ◽  
Oil Film ◽  
Pure Rolling ◽  
Rectangular Glass

In this paper, the EHL oil film thickness and shape between a needle roller and a flat rectangular glass in pure rolling oscillated working conditions had been measured based on optical interferometry. The EHL behavior affected by the applied load, oscillating frequency was investigated. The typical film shape varies of interference pictures on the maximum needle roller rotation velocity was obtained and compared each other. It is found the side constrictions are always the most severe and they are strongly speeds and loads dependence.

Development of an Efficient Oil Film Damper for Improving the Control of Rotor Vibration

1991 ◽  
Vol 113 (4) ◽  
pp. 557-562 ◽  
Author(s):  
Shiping Zhang ◽  
Litang Yan
Keyword(s):  
High Speed ◽  
Porous Metal ◽  
Porous Matrix ◽  
Squeeze Film ◽  
Oil Film ◽  
Squeeze Film Damper ◽  
Outer Race ◽  
Typical Experiment ◽  
Stiffness And Damping ◽  
Film Stiffness

An efficient oil film damper known as a porous squeeze film damper (PSFD) was developed for more effective and reliable vibration control of high-speed rotors based on the conventional squeeze film damper (SFD). The outer race of the PSFD is made of permeable sintered porous metal materials. The permeability allows some of the oil to permeate into and seep out of the porous matrix, with remarkable improvement of the squeeze film damping properties. The characteristics of PSFD oil film stiffness and damping coefficients and permeability, and also, the steady-state unbalance response of a simple rigid rotor and flexible Jeffcott’s rotor supported on PSFD and SFD are investigated. A typical experiment is presented. Investigations show that the nonlinear vibration characteristics of the unpressurized SFD system such as bistable jump phenomena and “lockup” at rotor pin-pin critical speeds could be avoided and virtually disappear under much greater unbalance levels with properly designed PSFD system. PSFD has the potential advantage of operating effectively under relatively large unbalance conditions.

Vibration Suppression Evaluation of Smart Journal Bearing Using Giant Magnetostrictive Actuators

2015 ◽  
Vol 642 ◽  
pp. 323-327
Author(s):  
W. Wang ◽  
Sheng Zong Cai ◽  
Chao Wu ◽  
P.L. Wong
Keyword(s):  
Journal Bearing ◽  
Vibration Suppression ◽  
Control Method ◽  
Coupling Model ◽  
Oil Film ◽  
Mechanical Coupling ◽  
Magnetostrictive Actuators ◽  
Order Of Magnitude ◽  
Rotor Center ◽  
Set Up

A new kind of smart hydrodynamic journal bearings with giant magnetostrictive actuators (GMA) is introduced. The static and dynamic displacement outputs of the designed GMA are up to tens of microns, about the same order of magnitude as the conventional journal bearing clearance. Vibration suppression of the new smart journal bearing is theoretically evaluated using a simple Jeffcott rotor-bearing system. Kinematic equations are set up including the magneto-mechanical coupling model for GMA. The bearing oil film force under large vibration is calculated using a fast and efficient non-stationary oil film database technique. The unbalance vibration orbit of the rotor center is simulated. A simple synchronous proportional control method for GMA with different control phases and gains is investigated. The suppress effect of unbalance vibration and improvement of oil whip unstable speed is evaluated. The simulation proves that the new journal bearing has better stability, and that rotor vibration can be actively suppressed.

The Measurement of Oil-Film Thickness in Gear Teeth

1960 ◽  
Vol 82 (1) ◽  
pp. 29-34 ◽  
Author(s):  
I. O. MacConochie ◽  
A. Cameron
Keyword(s):  
Film Thickness ◽  
Voltage Drop ◽  
Theoretical Work ◽  
Discharge Voltage ◽  
Constant Current ◽  
Oil Film ◽  
Gear Teeth ◽  
Order Of Magnitude ◽  
The Difference ◽  
Experimental Values

The voltage drop across thin oil films when a constant current of 1 amp is passed, i.e., the discharge voltage, is used to measure the oil-film thickness between loaded gear teeth while running. It is found that the thickness at the pitch line is between 1 and 4 × 10−4 in., which varies slightly with the viscosity and rather more strongly with load. The thickness at the tips and roots is very dependent on the tip relief. The conditions here may explain the difference between disk and gear tests. These experimental values are compared with theoretical work and are shown to be of the same order of magnitude.

scholarly journals Optical analysis of ball-on-ring mode test rig for oil film thickness measurement

Friction ◽  
2016 ◽  
Vol 4 (4) ◽  
pp. 324-334 ◽  
Author(s):  
Yaoguang Zhang ◽  
Wenzhong Wang ◽  
Shengguang Zhang ◽  
Ziqiang Zhao
Keyword(s):  
Film Thickness ◽  
Thickness Measurement ◽  
Optical Analysis ◽  
Test Rig ◽  
Oil Film ◽  
Ring Mode ◽  
Film Thickness Measurement
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