Correction to “The Flow Factors Considering the Elastic Deformation for the Rough Surface with a Non-Gaussian Height Distribution”

2008 ◽  
Vol 51 (4) ◽  
pp. 542-542
Author(s):  
Tan Wan Kim ◽  
Yong-Joo Cho
Keyword(s):  
Rough Surface ◽  
Elastic Deformation ◽  
Height Distribution ◽  
Non Gaussian

scholarly journals Radar Imaging Statistics of Non-Gaussian Rough Surface: A Physics-Based Simulation Study

2022 ◽  
Vol 14 (2) ◽  
pp. 311
Author(s):  
Cheng-Yen Chiang ◽  
Kun-Shan Chen ◽  
Ying Yang ◽  
Yang Zhang ◽  
Lingbing Wu
Keyword(s):  
Surface Roughness ◽  
Rough Surface ◽  
Rough Surfaces ◽  
Parameters Estimation ◽  
Statistical Characteristics ◽  
Height Distribution ◽  
Sar Imaging ◽  
Non Gaussian ◽  
Physics Based Simulation ◽  
Gaussian Surface

This paper investigates the radar image statistics of rough surfaces by simulating the scattered signal’s dependence on the surface roughness. Statistically, the roughness characteristics include the height probability density (HPD) and, to the second-order, the power spectral density (PSD). We simulated the radar backscattered signal by computing the far-field scattered field from the rough surface within the antenna beam volume in the context of synthetic aperture radar (SAR) imaging. To account for the non-Gaussian height distribution, we consider microscopic details of the roughness on comparable radar wavelength scales to include specularly, singly, and multiply scatterers. We introduce surface roughness index (RSI) to distinguish the statistical characteristics of rough surfaces with different height distributions. Results suggest that increasing the RMS height does not impact the Gaussian HPD surface but significantly affects the Weibull surface. The results confirm that as the radar frequency increases, or reaches a relatively larger roughness, the surface’s HPD causes significant changes in incoherent scattering due to more frequent multiple scattering contributions. As a result, the speckle move further away from the Rayleigh model. By examining individual RSI, we see that the Gaussian HPD surface is much less sensitive to RMS height than the Weibull HPD surface. We demonstrate that to retrieve the surface parameters (both dielectric and roughness) from the estimated RCS, less accuracy is expected for the non-Gaussian surface than the Gaussian surface under the same conditions. Therefore, results drawn from this study are helpful for system performance evaluations, parameters estimation, and target detection for SAR imaging of a rough surface.

scholarly journals Mixed elastohydrodynamic lubrication model of rotary lip seal with non-Gaussian surfaces: experimentation verification and numerical analysis on effects of sealed pressure

2021 ◽  
Vol 104 (2) ◽  
pp. 003685042110170
Author(s):  
Di Liu ◽  
Shaoping Wang ◽  
Jian Shi
Keyword(s):  
Rough Surface ◽  
Fluid Pressure ◽  
Elastohydrodynamic Lubrication ◽  
Periodic Variation ◽  
Simulation Method ◽  
Height Distribution ◽  
Lip Seal ◽  
System A ◽  
Sealing Performance ◽  
Non Gaussian

Many published models can be used to analyse the sealing performance of rotary lip seal. The surfaces are normally assumed to be periodic variation. However, the quasi-randomness of surface height distribution should be considered, especially the non-Gaussian distribution. Hence, a mixed elastohydrodynamic lubrication model with non-Gaussian surfaces is proposed and used to analyse the effects of sealed fluid pressure on the seal performance in this paper. Based on digital filter and Johnson’s translator system, a rough surface simulation method is introduced to simulate non-Gaussian rough surface. Based on this method the mixed lubrication model with non-Gaussian surfaces is built. The proposed model is verified by comparing the simulation results to experimental observations. Furthermore, it is hardly to find the research focused on the effects of sealed pressure. Hence, the effects of sealed fluid pressure on the seal performance is focused.

A Microscopic Wear Measurement Method for General Surfaces

2002 ◽  
Vol 124 (4) ◽  
pp. 829-833 ◽  
Author(s):  
Yeau-Ren Jeng ◽  
Zhi-Way Lin ◽  
Shiuh-Hwa Shyu
Keyword(s):  
Surface Roughness ◽  
Measurement Method ◽  
Current Method ◽  
Current Approach ◽  
Height Distribution ◽  
Initial Surface ◽  
Roughness Parameters ◽  
Wear Measurement ◽  
Non Gaussian ◽  
Worn Surfaces

A method was developed to measure the wear of general engineering surfaces based on the roughness parameters of the worn surfaces. This method does not require any information of the initial surface. The surface height distribution is described using Johnson translatory system where the loss of surface height is attributed to wear. Experiments of engine running in were conducted to validate the method. The results show that the current method can determine wear comparable to surface roughness. The current approach simplifies the profilometrical wear measurement and extends such a measurement to non-Gaussian surfaces.

Growth Front Roughening of Room Temperature Deposited Oligomer Thin Films

2000 ◽  
Vol 648 ◽  
Author(s):  
D. Tsamouras ◽  
G. Palasantzas ◽  
J. Th. M. De Hosson ◽  
G. Hadziioannou
Keyword(s):  
Thin Films ◽  
Film Thickness ◽  
Room Temperature ◽  
Growth Front ◽  
Silicon Substrates ◽  
Height Distribution ◽  
Force Microscopy ◽  
Atomic Force ◽  
Roughness Amplitude ◽  
Non Gaussian

AbstractGrowth front scaling aspects are investigated for PPV-type oligomer thin films vapor- deposited onto silicon substrates at room temperature. For film thickness d~15-300 nm, commonly used in optoelectronic devices, correlation function measurement by atomic force microscopy yields roughness exponents in the range H=0.45±0.04, and an rms roughness amplitude which evolves with film thickness as a power law σ∝ dβ with β=0.28±0.05. The non-Gaussian height distribution and the measured scaling exponents (H and β) suggest a roughening mechanism close to that described by the Kardar-Parisi-Zhang scenario.

White-Light Interferometric Sensor for Rough Surface Height Distribution Measurement

2010 ◽  
Vol 10 (6) ◽  
pp. 1125-1132 ◽  
Author(s):  
Lazo Mihajlo Manojlovic ◽  
Milos B. Zivanov ◽  
Aleksandar S. Marincic
Keyword(s):  
Rough Surface ◽  
White Light ◽  
Height Distribution ◽  
Distribution Measurement ◽  
Interferometric Sensor

Poly-Gaussian models of a non-Gaussian randomly rough surface

2012 ◽  
Vol 57 (4) ◽  
pp. 524-533 ◽  
Author(s):  
M. Ya. Litvak ◽  
V. I. Malyugin
Keyword(s):  
Rough Surface ◽  
Gaussian Models ◽  
Non Gaussian ◽  
Randomly Rough Surface

scholarly journals A Comparative Study on Asperity Peak Modeling Methods

2021 ◽  
Vol 34 (1) ◽  
Author(s):  
Wei Zhou ◽  
Daiyan Zhao ◽  
Jinyuan Tang ◽  
Jun Yi
Keyword(s):  
Rough Surface ◽  
Surface Profile ◽  
Statistical Characteristics ◽  
Height Distribution ◽  
Statistical Distributions ◽  
Spectral Moment ◽  
Correlation Pattern ◽  
Modeling Methods ◽  
Distribution Parameters ◽  
Moment Approach

AbstractThe peak identification scheme based method (three-point definition) and the spectral moments based method (spectral moment approach) are both widely used for asperity peak modeling in tribology. To discover the differences between the two methods, a great number of rough surface profile samples with various statistical distributions are first randomly generated using FFT. Then the distribution parameters of asperity peaks are calculated for the generated samples with both methods. The obtained results are compared and verified by experiment. The variation rules of the differences between the two methods with statistical characteristics of rough surfaces are investigated. To explain for the discovered differences, the assumptions by spectral moment approach that the joint distribution of surface height, slope and curvature is normal and that the height distribution of asperities is Gaussian, are examined. The results show that it is unreasonable to assume a joint normal distribution without inspecting the correlation pattern of [z], [z′] and [z′′], and that the height distribution of asperities is not exactly Gaussian before correlation length of rough surface increases to a certain extent, 20 for instance.

Influence of Materials Hardenability Parameters on the Machine Parts Characteristics after Unloading

2016 ◽  
Vol 723 ◽  
pp. 369-375 ◽  
Author(s):  
P.M. Ogar ◽  
D.B. Gorokhov
Keyword(s):  
Rough Surface ◽  
Half Space ◽  
Plastic Material ◽  
Practical Importance ◽  
Pressure Vessels ◽  
Design Stage ◽  
Real Surface ◽  
Height Distribution ◽  
Elastic Plastic ◽  
Elastic Plastic Material

This paper studies the problem of the relative area changing on a decrease of the load applied to the joint of roughness surfaces. The penetration of a rigid rough sphere (indenter) into the elastic hardenable half-space is initially considered, then the elastic crater restoring by unloading is considered. To defining elastic-plastic material, Hollomon’s power law is used. To describe a contact of a rigid rough surface with an elastic plastic half-space, the discrete model of a rough surface is used. Microasperities are represented as a set of identical spherical segments, the height distribution of which corresponds to the bearing profile curve of the real surface. The dependence the dimensionless force elastic-geometric parameter Fq on a relative amount of indentation ε at loading and the dependence of analogous parameter Fqe on amount of ε-Dε at unloading are obtained. The relations of relative contact areas h and he on dimensionless loading Fq and Fqe at loading and unloading for different values of a hardening exponent n and parameter are given. The obtained results are of practical importance for the performance prediction of fixed machine elements’ joints at the design stage, in particular for tightness supply of flange couplings and high pressure vessels seals.

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