Periodic Numerical Rough Surface Filtered Generation

2020 ◽  
Vol 143 (8) ◽  
Author(s):  
Runqing Liu ◽  
Tao Tao ◽  
Xuesong Mei
Keyword(s):  
Rough Surface ◽  
Rough Surfaces ◽  
Target Surface ◽  
Statistical Parameters ◽  
Random Surface ◽  
Periodic Surface ◽  
Actual Surface ◽  
Maximum Period ◽  
Good Improvement ◽  
Random Part

Abstract Numerical surface filtered generation is one of the main methods for generating numerical rough surfaces, but when faced with rough surfaces with waviness or large periodicity, traditional filtering methods cannot be implemented well. Because of this, the paper adopts the method of decomposing and synthesizing the maximum period and random part of the periodic rough surface. By decomposing the statistical parameters of the target surface, the statistical parameters of the ideal periodic surface and the random surface are generated, respectively, and then according to the surface parameters generate the surfaces and synthesize them. By comparing the statistical parameters and morphology of the synthesized surface with its actual surface, it can be found that this method can well achieve the generation of periodic rough surfaces, which is a good improvement to the original filter generation method.

Measured and Predicted Static Friction for Real Rough Surfaces in Point Contact

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
Jose M. García ◽  
Ashlie Martini
Keyword(s):  
Numerical Model ◽  
Yield Strength ◽  
Rough Surface ◽  
Rough Surfaces ◽  
Point Contact ◽  
Surface Profile ◽  
Static Friction ◽  
Cold Hardening ◽  
Quantitative Prediction ◽  
Statistical Parameters

A numerical model to predict static friction for metallic point contacts was developed and validated by comparison to experimental measurements using a specially designed test rig. Key aspects of the numerical model were the incorporation of a digitized real rough surface profile, application of discrete convolution fast Fourier transform (DC-FFT) to predict local asperity interference, and modification of the yield strength to capture the effect of cold hardening. It was found that these model features are critically important to quantitative prediction of static friction. The model significantly underestimated the static friction coefficient if randomly generated surfaces having statistical parameters the same as the measured rough surface were used; digitized real rough surfaces enabled accurate predictions. Further, the model was able to describe the static friction of worn surfaces after cold hardening was introduced through modification of material yield strength. This work illustrates the importance of incorporating the surface features and the change of those features with wear to accurately and reliably predict static friction.

Reduced Rough-Surface Parametrization for Use With the Discrete-Element Model

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Stephen T. McClain ◽  
Jason M. Brown
Keyword(s):  
Heat Transfer ◽  
Rough Surface ◽  
Surface Characterization ◽  
Rough Surfaces ◽  
Roughness Element ◽  
Three Dimensional ◽  
Element Model ◽  
Discrete Element ◽  
Diameter Distribution ◽  
Discrete Element Model

The discrete-element model for flows over rough surfaces was recently modified to predict drag and heat transfer for flow over randomly rough surfaces. However, the current form of the discrete-element model requires a blockage fraction and a roughness-element diameter distribution as a function of height to predict the drag and heat transfer of flow over a randomly rough surface. The requirement for a roughness-element diameter distribution at each height from the reference elevation has hindered the usefulness of the discrete-element model and inhibited its incorporation into a computational fluid dynamics (CFD) solver. To incorporate the discrete-element model into a CFD solver and to enable the discrete-element model to become a more useful engineering tool, the randomly rough surface characterization must be simplified. Methods for determining characteristic diameters for drag and heat transfer using complete three-dimensional surface measurements are presented. Drag and heat transfer predictions made using the model simplifications are compared to predictions made using the complete surface characterization and to experimental measurements for two randomly rough surfaces. Methods to use statistical surface information, as opposed to the complete three-dimensional surface measurements, to evaluate the characteristic dimensions of the roughness are also explored.

Reduced Rough-Surface Parameterization for Use With the Discrete-Element Model

2007 ◽  
Author(s):  
Stephen T. McClain ◽  
Jason M. Brown
Keyword(s):  
Heat Transfer ◽  
Rough Surface ◽  
Surface Characterization ◽  
Rough Surfaces ◽  
Roughness Element ◽  
Three Dimensional ◽  
Element Model ◽  
Discrete Element ◽  
Diameter Distribution ◽  
Discrete Element Model

The discrete-element model for flows over rough surfaces was recently modified to predict drag and heat transfer for flow over randomly-rough surfaces. However, the current form of the discrete-element model requires a blockage fraction and a roughness-element diameter distribution as a function of height to predict the drag and heat transfer of flow over a randomly-rough surface. The requirement for a roughness element-diameter distribution at each height from the reference elevation has hindered the usefulness of the discrete-element model and inhibited its incorporation into a computational fluid dynamics (CFD) solver. To incorporate the discrete-element model into a CFD solver and to enable the discrete-element model to become a more useful engineering tool, the randomly-rough surface characterization must be simplified. Methods for determining characteristic diameters for drag and heat transfer using complete three-dimensional surface measurements are presented. Drag and heat transfer predictions made using the model simplifications are compared to predictions made using the complete surface characterization and to experimental measurements for two randomly-rough surfaces. Methods to use statistical surface information, as opposed to the complete three-dimensional surface measurements, to evaluate the characteristic dimensions of the roughness are also explored.

Lubrication of Rough Surfaces by a Boundary Film-Forming Viscosity Modifier Additive

2005 ◽  
Vol 127 (1) ◽  
pp. 223-229 ◽  
Author(s):  
R. P. Glovnea ◽  
A. V. Olver ◽  
H. A. Spikes
Keyword(s):  
Rough Surface ◽  
Rough Surfaces ◽  
Viscosity Index ◽  
Functionalized Polymers ◽  
Contact Conditions ◽  
Film Forming ◽  
Boundary Film ◽  
Surface Contact ◽  
Lubricated Contact ◽  
Rough Surface Contact

In previous work it was shown that some functionalized polymers used as viscosity index improvers are able to form thick boundary lubricating films. This behavior results from adsorption of the polymer on metal surfaces to form a layer of enhanced viscosity adjacent to the surface. In the current work the behavior of one such polymer in rough surface contact conditions is studied, using both model and real rough surfaces. It is found that the polymer is able to form a thick boundary film in rough surface contact, just as it does with smooth surfaces. It is also shown that the effect of this boundary film is to significantly reduce friction in rolling-sliding, rough surface, lubricated contact.

Numerical Simulation of Rough Surface with Crossed Texture

2013 ◽  
Vol 321-324 ◽  
pp. 196-200 ◽  
Author(s):  
Ming Wei Chui ◽  
You Qian Feng ◽  
Wei Wang ◽  
Pei Lin Li ◽  
Zheng Chao Li
Keyword(s):  
Numerical Simulation ◽  
Rough Surface ◽  
Autocorrelation Function ◽  
Reference System ◽  
Surface Engineering ◽  
Rough Surfaces ◽  
Periodic Fluctuation ◽  
Simulated Surface ◽  
Simulation Results

To meet the demands for rough surfaces data in the research of surface engineering, contacts characteristic and so on, a new numerical simulation of rough surface is proposed. Based on FFT method, rough surface with single direction texture is simulated with circular cosine-exponent autocorrelation function (ACF), and the generated surface is rotated of different given angles respectively by rotation of reference system, then the rough surface with multi-direction texture is created by synthesizing the rotated surfaces. The simulation results show that, the ACF curves of generated surface is periodic fluctuation decay, and has a good fitting result with the predetermined ACF. The contrast result between simulated surface and measured surface shows the available of the proposed method.

Laser Sub-Micron Patterning of Rough Surfaces by Micro-Particle Lens Arrays

2011 ◽  
Vol 1 (3) ◽  
pp. 1-9 ◽  
Author(s):  
Ashfaq Khan ◽  
Zengbo Wang ◽  
Mohammad A Sheikh ◽  
Lin Li
Keyword(s):  
Rough Surface ◽  
Self Assembly ◽  
Glass Surface ◽  
Rough Surfaces ◽  
Flat Glass ◽  
Surface Patterning ◽  
Laser Surface ◽  
New Method ◽  
Experimental Investigations ◽  
Sio2 Spheres

Laser surface patterning by Contact Particles Lens Arrays (CPLA) has been widely utilized for patterning of smooth surfaces but there is no technique developed by which CPLA can be deposited on a rough surface. For deposition of CPLA, conventional techniques require the surface to be flat, smooth and hydrophilic. In this study, a new method for the deposition of CPLA on a rough surface is proposed and utilized for patterning. In this method, a hexagonal closed pack monolayer of SiO2 spheres was first formed by self-assembly on a flat glass surface. The formed monolayer of particles was picked up by a flexible sticky surface and then placed on the rough surface to be patterned. A Nd:YVO4 laser was used to irradiate the substrate with the laser passing through the sticky plastic and the particles. Experimental investigations have been carried out to determine the properties of the patterns.

Strongly Anisotropic Rough Surfaces

1979 ◽  
Vol 101 (1) ◽  
pp. 15-20 ◽  
Author(s):  
A. W. Bush ◽  
R. D. Gibson ◽  
G. P. Keogh
Keyword(s):  
Random Process ◽  
Rough Surface ◽  
Contact Area ◽  
Process Model ◽  
Rough Surfaces ◽  
Plasticity Index ◽  
Real Contact Area ◽  
Elastic Contact ◽  
Elastic Plastic ◽  
Real Contact

The statistics of a strongly anisotropic rough surface are briefly described. The elastic contact of rough surfaces is treated by approximating the summits of a random process model by parabolic ellipsoids and applying the Hertzian solution for their deformation. Load and real contact area are derived as functions of the separation and for all separations the load is found to be approximately proportional to the contact area. The limits of elastic/plastic contact are discussed in terms of the plasticity index.

Grain Flow for Rough Surfaces Considering Elastic/Inelastic Grain Collision

2004 ◽  
Author(s):  
Yeau-Ren Jeng ◽  
Hung-Jung Tsai
Keyword(s):  
Grain Size ◽  
Energy Loss ◽  
Rough Surface ◽  
Collision Energy ◽  
Rough Surfaces ◽  
Surface Characteristics ◽  
Flow Theory ◽  
Roughness Effects ◽  
Lubrication Equation ◽  
Grain Flow

Previous work by this group on an average lubrication equation for grain flow with roughness effects is extended to include grain-grain collision elasticity ranging from perfectly elastic to perfectly inelastic. The average lubrication equation is based on Haff’s grain flow theory, with flow factors from Patir and Cheng and Tripp’s use of perturbation. The derived flow factors are obtained as functions of rough surface characteristics, grain size and collision pattern. As collision energy loss approaches zero, the inelastic results approach those for perfectly elastic grain collision. The mathematical formulae for flow factors, grain/grain collision elasticity, grain size and roughness are presented, discussed. Predictions for the elastic and inelastic cases are graphically demonstrated and compared.

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