Scattering from an elastic shell and a doubly infinite fluid–solid interface with random surface roughness

1993 ◽  
Vol 93 (4) ◽  
pp. 2420-2420
Author(s):  
Garner C. Bishop ◽  
Judy Smith

A two-dimensional homogeneous random surface { y ( X )} is generated from another such surface { z ( X )} by a process of smoothing represented by y ( X ) = ∫ ∞ d u w ( u – X ) z ( u ), where w ( X ) is a deterministic weighting function satisfying certain conditions. The two-dimensional autocorrelation and spectral density functions of the smoothed surface { y ( X )} are calculated in terms of the corresponding functions of the reference surface { z ( X )} and the properties of the ‘footprint’ of the contact w ( X ). When the surfaces are Gaussian, the statistical properties of their peaks and summits are given by the continuous theory of surface roughness. If only sampled values of the surface height are available, there is a corresponding discrete theory. Provided that the discrete sampling interval is small enough, profile statistics calculated by the discrete theory should approach asymptotically those calculated by the continuous theory, but it is known that such asymptotic convergence may not occur in practice. For a smoothed surface { y ( X )} which is generated from a reference surface { z ( X )} by a ‘good’ footprint of finite area, it is shown in this paper that the expected asymptotic convergence does occur always, even if the reference surface is ideally white. For a footprint to be a good footprint, w ( X ) must be continuous and smooth enough that it can be differentiated twice everywhere, including at its edges. Sample calculations for three footprints, two of which are good footprints, illustrate the theory.


2010 ◽  
Vol 5 (5) ◽  
pp. 347 ◽  
Author(s):  
Wen-Ming Zhang ◽  
Guang Meng ◽  
Zhi-Ke Peng

2017 ◽  
Vol 64 (5) ◽  
pp. 2409-2416 ◽  
Author(s):  
Daniel Connelly ◽  
Tsu-Jae King Liu

1967 ◽  
Author(s):  
Bruce D. Van Deusen ◽  
Gerald E. Mccarron

2020 ◽  
Vol 69 (1) ◽  
Author(s):  
A. Tiwari ◽  
B. N. J. Persson

AbstractWe study the nominal (ensemble averaged) contact pressure p(x) acting on a cylinder squeezed in contact with an elastic half space with random surface roughness. The contact pressure is Hertzian-like for $$\alpha < 0.01$$ α < 0.01 and Gaussian-like for $$\alpha > 10$$ α > 10 , where the dimensionless parameter $$\alpha = h_{\rm rms}/\delta $$ α = h rms / δ is the ratio between the root-mean-square roughness amplitude and the penetration for the smooth surfaces case (Hertz contact).


2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
Xuntao Wang ◽  
Jianhu Feng ◽  
Hu Wang ◽  
Shidi Hong ◽  
Xiaohan Cheng ◽  
...  

Random surface roughness of bridge deck pavement just like random road surface roughness was simulated by the harmony superposition method in this paper. The dynamic load of vehicle was calculated by the random surface roughness of the deck pavement and the quarter-car model. A finite element model of a box girder bridge and its deck pavement was established, and the bonding condition between the adjacent layers was assumed to be contact bonding condition. The stress values of the asphalt concrete layer were calculated and analyzed when surface roughness condition, vehicle speed, and disengaging area changed. Results show that random surface roughness of deck pavement affected the stress trend of the asphalt concrete layer obviously. The appearance of disengaging area would increase the stress values of the asphalt concrete layer and the normal tensile stress value between the asphalt concrete layer and the waterproof layer. This would speed up the damage of the asphalt concrete layer and enlarge further the disengaging area.


Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3090 ◽  
Author(s):  
Lina Cao ◽  
Kursat Sendur

Random surface roughness and surface distortions occur inevitably because of various material processing and fabrication techniques. Tailoring and smoothing the surface roughness can be especially challenging for thermomechanically stable materials, including refractory metals, such as tungsten (W), and polar dielectrics, such as silicon carbide (SiC). The spectral reflectivity and emissivity of surfaces are significantly impacted by surface roughness effects. In this paper, we numerically investigated the surface roughness effects on the spectral reflectivity and emissivity of thermomechanically stable materials. Based on our results, we determined that surface roughness effects are strongly impacted by the correlation length of the Gaussian surface. In addition, our results indicate that surface roughness effects are stronger for the materials at the epsilon-near-zero region. Surface roughness effects are stronger between the visible and infrared spectral region for W and around the wavelength of 12 μ m for SiC, where plasma frequency and polar resonance frequency are located.


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