Housing Profile Design for Improved Apex Seal Lubrication Using a Finite Length Roller Elastohydrodynamic Lubrication Model

2020 ◽  
Vol 143 (8) ◽  
Author(s):  
Zhong Liu ◽  
Thomas Gu ◽  
David Pickens ◽  
Takayuki Nishino ◽  
Q. Jane Wang
Keyword(s):  
Finite Length ◽  
Surface Effect ◽  
Elastohydrodynamic Lubrication ◽  
Negative Effects ◽  
Transform Method ◽  
Gear Teeth ◽  
Negative Edge ◽  
Concave Shape ◽  
Rotary Engines ◽  
Fast Fourier Transform Method

Abstract Finite-length roller contacts are found in apex seal-housing interfaces in rotary engines, as well as in many other mechanical systems, such as those at the interfaces of meshing gear teeth, cam followers, and roller bearings. Rollers are usually designed with crowns and modified ends to mitigate the negative effects of misalignment, thermal deformation, and edge-induced non-uniform displacement. A crowned-roller elastohydrodynamic lubrication model is enriched and employed to investigate seven housing surface profiles, including a sinusoidal recess, sinusoidal ends, the combination design of a sinusoidal recess and sinusoidal ends, multiple sinusoidal recesses, a concave shape, and a concave shape with sinusoidal ends or round corners, aiming to improve the tribological performance of the interface via increasing the minimum film thickness but reducing the average and maximum film thicknesses, and lowering friction coefficient. The modified discrete convolution and fast Fourier transform method with duplicated padding is utilized to deal with the potential free-end-surface effect. The simulation results suggest that the combinations of a concave shape and sinusoidal ends, or round corners, are the best designs because they can help distribute the lubricant most uniformly without causing a negative edge effect.

Simulation of Plasto-Elastohydrodynamic Lubrication in Line Contacts of Infinite and Finite Length

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Tao He ◽  
Jiaxu Wang ◽  
Zhanjiang Wang ◽  
Dong Zhu
Keyword(s):  
Surface Roughness ◽  
Finite Length ◽  
3D Model ◽  
Three Dimensional ◽  
Elastohydrodynamic Lubrication ◽  
Axial Direction ◽  
Contact Length ◽  
Line Contact ◽  
Line Contacts ◽  
3D Surface Topography

Line contact is common in many machine components, such as various gears, roller and needle bearings, and cams and followers. Traditionally, line contact is modeled as a two-dimensional (2D) problem when the surfaces are assumed to be smooth or treated stochastically. In reality, however, surface roughness is usually three-dimensional (3D) in nature, so that a 3D model is needed when analyzing contact and lubrication deterministically. Moreover, contact length is often finite, and realistic geometry may possibly include a crowning in the axial direction and round corners or chamfers at two ends. In the present study, plasto-elastohydrodynamic lubrication (PEHL) simulations for line contacts of both infinite and finite length have been conducted, taking into account the effects of surface roughness and possible plastic deformation, with a 3D model that is needed when taking into account the realistic contact geometry and the 3D surface topography. With this newly developed PEHL model, numerical cases are analyzed in order to reveal the PEHL characteristics in different types of line contact.

Study on Measurement of Thin Film Thickness with Lateral Shearing Interferometry

2013 ◽  
Vol 718-720 ◽  
pp. 848-852
Author(s):  
Jun Hong Su ◽  
Ying Shi ◽  
Jin Man Ge
Keyword(s):  
Film Thickness ◽  
Transform Method ◽  
Shearing Interferometry ◽  
Platform Process ◽  
Fast Fourier Transform Method ◽  
Lateral Shearing ◽  
Phase Unwrap ◽  
Technical Indicator ◽  
Lateral Shearing Interferometry ◽  
Shearing Interference

The film thickness is an important technical indicator of film devices, and its accuracy directly affects various performances of optical components. In fabrication process of film device, fast and accurate measurement of film thickness has positive significance on product quality control. In this paper, measure film thickness with lateral shearing interferometry. Collect interferograms through structured lateral shearing interference platform, process interferogram with Fast Fourier Transform method to extract phase, unwrap the wrapped phase to achieve phase value. Finally, calculate film thickness based on lateral shearing interference principle. The thickness of sample is 119.6800nm measured by this method, basically the same with the result 120.6036nm that measured by ZYGO interferometer. This experiment shows that lateral shearing interferometry not only suit to measurement of film thickness, but also abundant high-precision method of measuring film thickness, and has high practical value.

An Approach to the Use of an External Magnetic Field As a Diagnostic Sign of an Asynchronous Motor Malfunction

2021 ◽  
Vol 64 (3) ◽  
pp. 18-23
Author(s):  
Ildar Yamansarin ◽  
◽  
Mikhail Salikov ◽  
Alexander Padeev ◽  
Dmitry Surkov ◽  
...  
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Short Circuit ◽  
Asynchronous Motor ◽  
Technical Condition ◽  
Stator Winding ◽  
Electric Motors ◽  
Transform Method ◽  
Fast Fourier Transform Method ◽  
Measurement Location

The article deals with the issues related to the possibility of diagnosing the technical condition of an asyn-chronous electric motor by an external magnetic field. The justification of the problems associated with the di-agnosis of electric motors is given. The difficulties that arise when measuring the external magnetic field of electric motors, as well as the devices with which it is possible to carry out measurements, are described. The re-lationship between the EMF of the sensor and the external magnetic field is shown. The results of processing the EMF waveforms induced by an external magnetic field in an inductive sensor for various electric motors are presented. The processing was carried out by the fast Fourier transform method. The external magnetic field contains the first harmonic and various harmonics that are multiples of the combination of the stator teeth, or the sum of the stator and rotor teeth that fall on one pair of poles. The ratio of the amplitudes of the first and tooth harmonics is affected by the measurement location and the orientation of the sensor. Diagrams showing the ratio of the main and tooth harmonics at different points of the motor body are constructed. The depend-ences of the harmonic amplitudes on the magnitude of the magnetizing current of the stator are given. Changes in the amplitudes and spectrum of harmonics in the presence and absence of an inter-turn short circuit in the stator winding are shown. Diagrams of the circular external magnetic field for the main and higher harmonics are constructed. The study shows the possibility of using an external magnetic field to detect inter-turn short circuits of the stator winding.

Discussion of Short-Wavelength Laser Beam Focus Using Fast Fourier Transform Method

2011 ◽  
Vol 31 (5) ◽  
pp. 0507001
Author(s):  
杨美霞 Yang Meixia ◽  
钟鸣 Zhong Ming ◽  
任钢 Ren Gang ◽  
何衡湘 He Hengxiang ◽  
刘文兵 Liu Wenbing ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Laser Beam ◽  
Fast Fourier Transform ◽  
Short Wavelength ◽  
Transform Method ◽  
Fourier Transform Method ◽  
Fast Fourier Transform Method
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