A Simulation Method for Non-Gaussian Rough Surfaces Using Fast Fourier Transform and Translation Process Theory

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Yuechang Wang ◽  
Ying Liu ◽  
Gaolong Zhang ◽  
Yuming Wang
Keyword(s):  
Fourier Transform ◽  
Fast Fourier Transform ◽  
Rough Surface ◽  
Tribological Behavior ◽  
Rough Surfaces ◽  
Simulation Method ◽  
Process Theory ◽  
Asperity Contact ◽  
Translation Process ◽  
Non Gaussian

The simulated rough surface with desired parameters is widely used as an input for the numerical simulation of tribological behavior such as the asperity contact, lubrication, and wear. In this study, a simulation method for generating non-Gaussian rough surfaces with desired autocorrelation function (ACF) and spatial statistical parameters, including skewness (Ssk) and kurtosis (Sku), was developed by combining the fast Fourier transform (FFT), translation process theory, and Johnson translator system. The proposed method was verified by several numerical examples and proved to be faster and more accurate than the previous methods used for the simulation of non-Gaussian rough surfaces. It is convenient to simulate the non-Gaussian rough surfaces with various types of ACFs and large autocorrelation lengths. The significance of this study is to provide an efficient and accurate method of non-Gaussian rough surfaces generation to numerically simulate the tribological behavior with desired rough surface parameters.

Investigations Into Asperity Persistence in Heavily Loaded Contacts

1999 ◽  
Vol 121 (3) ◽  
pp. 441-448 ◽  
Author(s):  
I. Lee-Prudhoe ◽  
R. S. Sayles ◽  
A. Kaderic
Keyword(s):  
Rough Surface ◽  
Simulation Models ◽  
Simulation Method ◽  
Asperity Contact ◽  
Local Contact ◽  
Before And After ◽  
Indentation Tests ◽  
Mechanisms Of Persistence ◽  
Contact Pressures ◽  
Smooth Roller

Experimental results are presented along the lines of the early work of Moore (1948) where a hard smooth roller is pressed into a softer rough surface to study the resulting real to apparent areas of contact and their associated local contact pressures. Results are presented for a hard steel roller deforming mild-steel and aluminum-alloy rough surface specimens. An analysis of the local contact mechanics is performed before and after indentation using a recently developed numerical elastic contact simulation method which allows local asperity contact pressures and areas to be studied in detail. The method is shown to reveal the level and distribution of pressures and asperity contact areas prevalent during the indentation process, and therefore allows the contribution of elastic and plastic load support to be quantified. The persistence of asperities during such indentation tests is discussed in terms of the pressures the asperities can support in relation to reported mechanisms of persistence. Results of subsequent sub-surface stresses are also presented and discussed in terms of how the method might be used to create an elastic-plasticdeformation model that can account for asperity persistence in future numerical contact simulation models.

A Model of Mixed Lubrication for the Repeated Sliding Problem Considering the Reloading Characteristic: Application to Ring/Liner Conjunction

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Chunxing Gu ◽  
Di Zhang ◽  
Xiaohong Ding ◽  
Shuwen Wang
Keyword(s):  
Mathematical Model ◽  
Cyclic Loading ◽  
Rough Surface ◽  
Mixed Lubrication ◽  
Metal Contact ◽  
Asperity Contact ◽  
Surface Contact ◽  
Loading Problem ◽  
Non Gaussian ◽  
Gaussian Surface

Abstract Loading, unloading, and reloading of rough surface contacts are common for most friction pairs. However, usually, only loading characteristic is concerned in the modeling of the cyclic loading problem. In this paper, a comprehensive mathematical model of mixed lubrication was developed for the lubricated friction pairs under cyclic loading. The metal contact was calculated by an improved asperity contact model of elastic–plastic with the loading, unloading, and reloading characteristics in consideration. The developed model was applied to the ring/liner conjunction, as its contact problem was the typical cyclic loading problem. Different from the previous studies, assuming the “virgin” topography of the rough surface, the current one accounts for the plastic deformation of surface asperities, occurring during the first few cycles and leading to the significant roughness modification. It appears that considering the reloading characteristics is necessary, whether it is a Gaussian surface contact or a non-Gaussian surface contact.

The Effect of Anisotropy on the Percolation Threshold of Sealing Surfaces

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Zhimeng Yang ◽  
Jianhua Liu ◽  
Xiaoyu Ding ◽  
Feikai Zhang
Keyword(s):  
Fourier Transform ◽  
Theoretical Result ◽  
Fast Fourier Transform ◽  
Percolation Threshold ◽  
Rough Surface ◽  
Conjugate Gradient ◽  
Surface Anisotropy ◽  
Sealing Performance ◽  
The Relationship ◽  
Theoretical Results

The percolation threshold strongly affects sealing performance. This paper investigates the relationship between the percolation threshold and the rough surface anisotropy, which is represented by the Peklenik number, γ. A series of anisotropic rough surfaces were generated and the conjugate gradient-fast Fourier transform (CG-FFT) method was used to determine the percolation threshold. The percolation threshold was found to be A/A0≈0.484±0.009 (averaged over 45 surfaces) was established for an isotropic rough surface (γ=1). Furthermore, it was also found that the percolation threshold decreased from A/A0≈0.528±0.011 to A/A0≈0.431±0.008 as 1/γ increased from 0.6 to 2. Our results differ from the theoretical result of Persson et al., where A/A0=γ/(1+γ). Comparing our calculated results with the theoretical results established the presence of an intersection value of 1/γ that was related to the effect of elastic deformation on the percolation threshold. When 1/γ was smaller than the intersection value, our calculated results were lower than the theoretical ones; and when 1/γ was greater than the intersection value, our calculated results were higher than the theoretical ones.

Recovery of Modal Information From a Beam Undergoing Random Vibration

1974 ◽  
Vol 96 (4) ◽  
pp. 1307-1313
Author(s):  
W. W. Parmenter ◽  
R. G. Christiansen
Keyword(s):  
Fourier Transform ◽  
Structural Analysis ◽  
Fast Fourier Transform ◽  
Random Process ◽  
Random Vibration ◽  
Structural Information ◽  
Process Theory ◽  
Acceleration Response ◽  
Vibration Data ◽  
Random Process Theory

An organized approach for implementing the techniques of random process theory in the recovery of structural information from random vibration data is presented. The boundaries of various configured Bernoulli-Euler like beams are subjected to random vibrations and the acceleration response of these beams is measured and recorded. The Fast Fourier Transform (FFT) makes the use of random process theory both a feasible and economical tool for experimental structural analysis.

scholarly journals A High Precision Modeling Technology of Material Surface Microtopography and Its Influence on Interface Mechanical Properties

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2914
Author(s):  
Yunlong Wang ◽  
Xiaokai Mu ◽  
Cong Yue ◽  
Wei Sun ◽  
Chong Liu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Surface Topography ◽  
Rough Surface ◽  
Simulation Method ◽  
Material Surface ◽  
Hierarchical Algorithm ◽  
Multi Scale ◽  
Surface Microtopography ◽  
Mating Surface ◽  
Non Gaussian

In order to accurately and effectively obtain the contact performance of the mating surface under the material surface topography characteristics, a numerical simulation method of rough surface based on the real topography characteristics and a multi-scale hierarchical algorithm of contact performance is studied in this paper. Firstly, the surface topography information of materials processed by different methods was obtained and characterized by a measuring equipment; Secondly, a non-Gaussian model considering kurtosis and skewness was established by Johnson transform based on Gaussian theory, and a rough surface digital simulation method based on real surface topography was formed; Thirdly, a multi-scale hierarchical algorithm is given to calculate the contact performance of different mating surfaces; Finally, taking the aeroengine rotor as the object, the non-Gaussian simulation method was used to simulate the mating surfaces with different topographies, and the multi-scale hierarchical algorithm was used to calculate the contact performance of different mating surfaces. Analysis results showed that the normal contact stiffness and elastic–plastic contact area between the mating surfaces of assembly 1 and assembly 2 are quite different, which further verifies the feasibility of the method. The contents of this paper allow to perform the fast and effective calculation of the mechanical properties of the mating surface, and provide a certain analysis basis for improving the surface microtopography characteristics of materials and the product performance.

Research on the Obtainment of Topography Parameters by Rough Surface Simulation With Fast Fourier Transform

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Yan Fei He ◽  
Jin Yuan Tang ◽  
Wei Zhou ◽  
Dong Ri Liao
Keyword(s):  
Fourier Transform ◽  
Fast Fourier Transform ◽  
Rough Surface ◽  
Autocorrelation Function ◽  
Correlation Length ◽  
Relevant Literature ◽  
Contact Model ◽  
Radius Of Curvature ◽  
Numerical Fitting

Asperity radius of curvature and asperity density, which are generally obtained from rough surface simulation with fast Fourier transform (FFT), are the two essential parameters for statistical contact model. In simulation, however, the value of a parameter (defined as “autocorrelation function (ACF) truncation length” in this paper), which is arbitrarily chosen and has been paid little attention to in most relevant literature, is found to have a great effect on topography parameters, regardless of the methods chosen to calculate them. Improper determination of the ACF truncation length may induce erroneous results. This paper points out how to make the proper determination of the ACF truncation length to guarantee a certain degree of precision and explains why improper determination of the ACF truncation length may cause serious errors when calculating the topography parameters. Besides, the asperity radius of curvature and the asperity density of the generated rough surfaces are calculated using the eight-summit identification method, and their formulae in terms of correlation length are obtained through numerical fitting.

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.

A New Adaptive-Surface Elastic-Plastic Contact Model of Rough Surfaces: Parameter Correlations

2006 ◽  
Vol 532-533 ◽  
pp. 961-964
Author(s):  
Min Song
Keyword(s):  
Rough Surface ◽  
Root Mean Square ◽  
Rough Surfaces ◽  
Computing Time ◽  
Contact Model ◽  
Asperity Contact ◽  
Mean Square ◽  
Elastic Plastic ◽  
Surface Profiles

Based on an presented adaptive-surface elastic-plastic asperity contact model which can greatly decrease contact computing time and keep the precision loss less than 5%, a series of 2-D rough surface profiles with different roughness and correlative length are numerically generated to investigate how to select the threshold used in this model for different adaptive rough surfaces. The results show that well acceptable precision of the elastic-plastic contact calculation would be derived when the ratio of threshold to root mean square curvature, δ 1.0 10 6mm2 − < × .

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