Computational Performance of GTD-RT Applied for Evaluation of Electromagnetic Scattering on Rough Surfaces

2021 ◽  
Vol 36 (6) ◽  
pp. 610-621
Author(s):  
Asmaa Farahat ◽  
Khalid Hussein
Keyword(s):  
Surface Roughness ◽  
Plane Wave ◽  
Rough Surface ◽  
Electromagnetic Scattering ◽  
Geometric Model ◽  
Computational Method ◽  
Surface Model ◽  
Angle Of Incidence ◽  
Scattering Pattern ◽  
Computational Performance

In this paper, a new robust computational method that applies the geometrical theory of diffraction (GTD) in conjunction with the ray tracing (RT) technique is developed to evaluate the electromagnetic scattering pattern due to a plane wave represented as beam of parallel rays incident on a rough surface of quite arbitrary statistical parameters. The development of the proposed technique is explained in detail taking into consideration the generation of the geometrical model of the rough surface. The Fresnel reflection model is applied under the assumption of arbitrary electrical and optical properties of the rough surface material. Also the polarization of the plane wave primarily incident on the rough surface is taken into consideration. The algorithm developed in the present work accounts for multiple bounces of an incident ray and, hence, it can be considered arbitrary higher-order GTD-RT technique. The accuracy of the obtained results is verified through the comparison with the experimental measurements of the scattering pattern of a light beam incident on rough sheets with specific statistical properties. The numerical results of the present work are concerned with investigating the dependence of the scattering pattern on the surface roughness, refractive index, angle of incidence, and the resolution of the geometric model of the rough surface. Also, it is shown that, for limited resolution of the rough surface model, the accuracy of the calculated scattered field depends on the angle of incidence of the primary beam and the surface roughness.

The Contact of Two Nominally Flat Rough Surfaces

1970 ◽  
Vol 185 (1) ◽  
pp. 625-633 ◽  
Author(s):  
J. A. Greenwood ◽  
J. H. Tripp
Keyword(s):  
Surface Roughness ◽  
General Theory ◽  
Rough Surface ◽  
Rough Surfaces ◽  
Deformation Mode ◽  
Surface Model ◽  
Geometrical Properties ◽  
Rough Plane ◽  
Surface Contact ◽  
Compliance Curve

Most models of surface contact consider the surface roughness to be on one of the contacting surfaces only. The authors give a general theory of contact between two rough plane surfaces. They show that the important results of the previous models are unaffected: in particular, the load and the area of contact remain almost proportional, independently of the detailed mechanical and geometrical properties of the asperities. Further, a single-rough-surface model can always be found which will predict the same laws as a given two-rough-surface model, although the required model may be unrealistic. It does not seem possible to deduce the asperity shape or deformation mode from the load-compliance curve.

Electromagnetic scattering by a dielectric sphere partially buriedin an infinte plane

2002 ◽  
Vol 80 (9) ◽  
pp. 979-986
Author(s):  
A -K Hamid ◽  
M Hamid
Keyword(s):  
Plane Wave ◽  
Electromagnetic Scattering ◽  
Plane Electromagnetic Wave ◽  
Ground Plane ◽  
Scattering Problem ◽  
Dielectric Constants ◽  
Angle Of Incidence ◽  
Spherical Scatterer ◽  
Incident Plane ◽  
The Given

An analytical solution of the scattering problem of a plane electromagnetic wave scattered by a dielectric spherical scatterer residing or partially buried in an infinite perfectly conducting ground plane is formulated in conjunction with the method of images. With imaging, the geometry is replaced by two touching or overlapping dielectric spheres in the absence of the ground plane, but with the given incident plane wave and its plane-wave image to satisfy the boundary conditions on the ground plane in the original problem. Numerical results are presented for the normalized scattering cross section at an arbitrary height from the ground plane, at any specific angle of incidence, and different relative dielectric constants. PACS Nos.: 41.10H, 41.90

scholarly journals Fretting Wear Mechanical Analysis of Double Rough Surfaces Based on Energy Method

2021 ◽  
Author(s):  
Ling Li ◽  
Ganghua Li ◽  
JingJjing Wang ◽  
Xiaohui Shi ◽  
Anjiang Cai
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Rough Surface ◽  
Rough Surfaces ◽  
Research Work ◽  
Mechanical Analysis ◽  
Fretting Wear ◽  
Surface Model ◽  
Dissipation Model ◽  
And Performance

Abstract A fretting wear model of rough surface that conforms to the actual situation is established to accurately reveal the wear mechanism of the connection structure. In the ABAQUS software, the UMESHMOTION subroutine and the energy dissipation model are used to simulate the fretting wear of double rough surfaces. The new model, a single rough surface model, and a smooth model are compared to analyze the differences between them. In addition, the influence of surface roughness, material, and friction coefficient on the fretting wear of rough surfaces is systematically explored through finite element simulation. The results show that the reliability of the model has been verified through Hertz’s theory and experiments. The stress and wear of the contact surface are more realistically reflected by the double roughness model. Besides, with the increase of surface roughness and material rigidity and the decrease of friction coefficient, the wear of the double rough surface model becomes more severe. The research work provides a theoretical basis for the design and performance prediction of the connection structure.

Effects of Rough Surface on Contact Depth for Instrumented Microindentation Using Spherical Indenter

2007 ◽  
Vol 124-126 ◽  
pp. 1337-1340 ◽  
Author(s):  
Ju Young Kim ◽  
Jung Jun Lee ◽  
Yun Hee Lee ◽  
Jae Il Jang ◽  
Dong Il Kwon
Keyword(s):  
Surface Roughness ◽  
Rough Surface ◽  
Indentation Depth ◽  
Flat Surface ◽  
Spherical Indenter ◽  
Surface Model ◽  
Contact Depth ◽  
Deformation State ◽  
Microindentation Testing ◽  
Source Of Error

Surface roughness is main source of error in instrumented microindentation when it is not negligible relative to the indentation depth. The effect of a rough surface on the results of instrumented microindentation testing using spherical indenter was analyzed by applying the contact depth model, which takes surface roughness into account. Improved variations in hardness and Young’s modulus were shown for W and Ni when the results were analyzed by this rough-surface model, while these values were underestimated with increasing surface roughness when analyzed by the flat-surface model. The deformation state of asperities underneath spherical indenter was also discussed.

Impact of medical titanium implant surface on the efficiency of fibrointegration

2020 ◽  
pp. 50-55
Author(s):  
T. R. Davydova ◽  
А. I. Shaikhaliev ◽  
D. A. Usatov ◽  
G. A. Gasanov ◽  
R. S. Korgoloev
Keyword(s):  
Surface Roughness ◽  
Titanium Dioxide ◽  
Rough Surface ◽  
Soft Tissues ◽  
Titanium Implant ◽  
Implant Surface ◽  
Anatase Structure ◽  
Bioactive Coating ◽  
Cell Structures ◽  
Titanium Alloy Ti6al4v

The aim of this study was to study the effect of surface branching of titanium endoprostheses on the efficiency of fibrointegration. The object of the study was samples of titanium alloy Ti6Al4V in the form of disks with a diameter of 5 mm and a thickness of 1 mm with various surface treatments: 1) samples with a rough surface after sandblasting; 2) samples with a rough surface after sandblasting with a bioactive coating of titanium dioxide TiO2 with anatase structure. The study of surface roughness was carried out by profilometry. Evaluation of the spreading and proliferation of cells on the surface of test samples, as well as evaluation of the effectiveness of fibrointegration was carried out according to standard methods using scanning electron microscopy. During the experiments, mesinchymal stem cells were sown on test samples and the test samples were introduced into the soft tissues of experimental animals. Based on the results obtained, it was concluded that the technology of forming rough surfaces by sandblasting does not provide high uniformity and reproducibility in the nanometer range and, apparently, another method for obtaining a rough surface should be chosen. The application of a bioactive coating of titanium dioxide TiO2 with the anatase structure to the surface of titanium endoprostheses increases the efficiency of fibrointegration, however, primarily the fibrointegration of titanium endoprostheses depends on their surface roughness, which determines the concentration of cell structures, the intensity of their adhesion and the ability to fibrointegrative process.

scholarly journals Effects of Roughness on Stresses in an Oxide Scale Formed on a Superalloy Substrate

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 479
Author(s):  
Yang Zhao ◽  
Fan Sun ◽  
Peng Jiang ◽  
Yongle Sun
Keyword(s):  
Residual Stress ◽  
Surface Roughness ◽  
Residual Stresses ◽  
Oxide Scale ◽  
Rough Surface ◽  
Alumina Scale ◽  
Growth Stress ◽  
Oxide Growth ◽  
Substrate Thickness ◽  
Roughness Effect

The effects of surface roughness on the stresses in an alumina scale formed on a Fecralloy substrate are investigated. Spherical indenters were used to create indents with different radii and depths to represent surface roughness and then the roughness effect was studied comprehensively. It was found that the residual stresses in the alumina scale formed around the rough surface are almost constant and they are dominated by the curvature rather than the depth of the roughness. Oxidation changes the surface roughness. The edge of the indent was sharpened after oxidation and the residual stress there was released presumably due to cracking. The residual stresses in the alumina scale decrease with increase in oxidation time, while the substrate thickness has little effect, given that the substrate is thicker than the alumina scale. Furthermore, the effect of roughness on the oxide growth stress is analysed. This work indicates that the surface roughness should be considered for evaluation of stresses in coatings.

Effect of Rolling Velocity and Maximum Hertzian Pressure on Fluid Film in Steady State EHL Line Contact with Rough Surface and Linear Piezoviscosity

2014 ◽  
Vol 592-594 ◽  
pp. 1371-1375
Author(s):  
Nitesh Talekar ◽  
Punit Kumar
Keyword(s):  
Surface Roughness ◽  
Steady State ◽  
Film Thickness ◽  
Rough Surface ◽  
Computer Code ◽  
Fluid Film ◽  
Line Contact ◽  
Rolling Velocity ◽  
Load Carrying ◽  
Lubricated Contact

Consideration of surface roughness in steady state EHL line contact is the first step towards understanding the lubrication of rough surface problem. Current paper investigates the use of sinusoidal waviness in the contact; more precisely it gives performance of real fluid in EHL line contact. The effect of various parameters like rolling velocity (U) and maximum Hertzian pressure (ph) on surface roughness by using properties of linear and exponential piezo-viscosity is taken into consideration to evaluate behavior of pressure distribution of load carrying fluid film and film thickness. Full isothermal, Newtonian simulation of EHL problem gives described effects. Spiking or fluctuation of pressure and film thickness curves is expected to show presence of irregularities on the surface chosen and amount of fluctuation depends on certain parameters and intensity of irregularities present. Rolling side domain of-4.5 ≤ X ≤ 1.5 with grid size ∆X=0.01375 is selected. A computer code is developed to solve Reynolds equation, which governs the generation of pressure in the lubricated contact zone is discritized and solved along with load balance equation using Newton-Raphson technique.

Effect of Surface Roughness on the Total Hemispherical and Specular Reflectance of Metallic Surfaces

1964 ◽  
Vol 86 (2) ◽  
pp. 193-199 ◽  
Author(s):  
R. C. Birkebak ◽  
E. M. Sparrow ◽  
E. R. G. Eckert ◽  
J. W. Ramsey
Keyword(s):  
Surface Roughness ◽  
Black Body ◽  
Black Body Radiation ◽  
The Other ◽  
Angle Of Incidence ◽  
Metallic Surfaces ◽  
Specular Reflectance ◽  
Other Hand ◽  
Hemispherical Reflectance ◽  
Effect Of Surface

Measurements have been made of the hemispherical and specular reflectance of metallic surfaces of controlled roughness. The surfaces, which were ground nickel rectangles, were irradiated at various angles of incidence by a beam of black-body radiation, the temperature of which was also varied. The instrumentation which was devised to perform the experiments is described. The measurements show that beyond a certain surface roughness, the hemispherical reflectance is virtually independent of further increases in roughness. On the other hand, the specular reflectance decreases steadily with increasing roughness. Additionally, the hemispherical reflectance is found to be quite insensitive to the angle of incidence, while the specular reflectance increases with angle of incidence for the rougher surfaces.

Electromagnetic Scattering and Inverse Scattering of Layered Media with a Slightly Rough Surface

2011 ◽  
Vol 28 (1) ◽  
pp. 014102 ◽  
Author(s):  
Zhi-Wei Lin ◽  
Xin Xu ◽  
Xiao-Juan Zhang ◽  
Guang-You Fang
Keyword(s):  
Rough Surface ◽  
Inverse Scattering ◽  
Electromagnetic Scattering ◽  
Layered Media

Enhancement of reflection and backscattering components by plane wave imaging for estimation of surface roughness

2021 ◽  
Author(s):  
Kazuhiro Tochigi ◽  
Ryo Nagaoka ◽  
Jens Erik Wilhjelm ◽  
Hideyuki Hasegawa
Keyword(s):  
Surface Roughness ◽  
Plane Wave ◽  
Arterial Wall ◽  
Early Stage ◽  
Mean Value ◽  
Luminal Surface ◽  
Ultrasonic Echo ◽  
Wave Imaging ◽  
The Mean ◽  
Reflection Component

Abstract In the early stage of atherosclerosis, the luminal surface of the arterial wall becomes rough. Methods for distinguishing between the reflected and backscattered components in the ultrasonic echo from the arterial wall has the potential to be used as a method for assessment of the roughness of the arterial wall. In this study, we proposed a method to distinguish between the reflected and backscattered components using a technique based on plane wave compounding. This method was evaluated by experiments using planar phantoms with rough surfaces made of polyurethane rubber. The coefficient of variation calculated from the mean value of the reflection component and the standard deviation of the backscattering component was proportional to the roughness of the rubber phantom. This result shows the potential usefulness of this method for analyzing surface roughness of the arterial wall.

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