scholarly journals Recent Advancements in Fractal Geometric-Based Nonlinear Time Series Solutions to the Micro-Quasistatic Thermoviscoelastic Creep for Rough Surfaces in Contact

2011 ◽  
Vol 2011 ◽  
pp. 1-29 ◽  
Author(s):  
Osama M. Abuzeid ◽  
Anas N. Al-Rabadi ◽  
Hashem S. Alkhaldi
Keyword(s):  
Surface Roughness ◽  
Rough Surfaces ◽  
Power Laws ◽  
Experimental Models ◽  
Experimental Results ◽  
Closed Form Solutions ◽  
In Series ◽  
Standard Linear Solid ◽  
Standard Linear ◽  
Surface Creep

To understand the tripological contact phenomena, both mathematical and experimental models are needed. In this work, fractal mathematical models are used to model the experimental results obtained from literature. Fractal geometry, using a deterministic Cantor structure, is used to model the surface topography, where recent advancements in thermoviscoelastic creep contact of rough surfaces are introduced. Various viscoelastic idealizations are used to model the surface materials, for example, Maxwell, Kelvin-Voigt, Standard Linear Solid and Jeffrey media. Such media are modelled as arrangements of elastic springs and viscous dashpots in parallel and/or in series. Asymptotic power laws, through hypergeometric series, were used to express the surface creep as a function of remote forces, body temperatures and time. The introduced models are valid only when the creep approach of the contact surfaces is in the order of the size of the surface roughness. The obtained results using such models, which admit closed-form solutions, are displayed graphically for selected values of the systems' parameters; the fractal surface roughness and various material properties. Results obtained showed good agreement with published experimental results, where the utilized methodology can be further extended to the utilization for the contact of surfaces within micro- and nano-electronic devices, circuits and systems.

Influence of surface roughness on the wetting angle

1995 ◽  
Vol 10 (8) ◽  
pp. 1984-1992 ◽  
Author(s):  
X.B. Zhou ◽  
J.Th.M. De Hosson
Keyword(s):  
Surface Roughness ◽  
Gaussian Distribution ◽  
Rough Surfaces ◽  
Contact Angles ◽  
Wetting Angle ◽  
Experimental Results ◽  
Solid Surfaces ◽  
Roughness Measurements

A this paper the influence of surface roughness on contact angles in the system of liquid Al wetting solid surfaces of Al2O3 has been studied. It was observed that contact angles of liquid Al vary significantly on different rough surfaces of Al2O3. A model is proposed to correlate contact angles with conventional roughness measurements and wavelengths by assuming a cosine profile of rough grooves with a Gaussian distribution of amplitudes. In comparison with the experimental results, the model provides a good estimate for describing the influence of surface roughness on contact angles of liquid Al on Al2O3.

Parametric Vibration of Viscoelastic Moving Belts Using Standard Linear Solid Model

2001 ◽  
Author(s):  
Zhichao Hou ◽  
Jean W. Zu
Keyword(s):  
Order Approximation ◽  
Dynamic Responses ◽  
Solid Model ◽  
Nontrivial Solutions ◽  
Closed Form Solutions ◽  
Standard Linear Solid Model ◽  
Standard Linear Solid ◽  
Standard Linear ◽  
The Stability ◽  
First Order Approximation

Abstract By using a standard linear solid model to describe the viscoelasticity of the belt material, a vibration analysis of a parametrically excited moving belt is performed. Closed-form solutions at principal resonance and summation resonance are derived at the first order approximation. The existence conditions and stability are discussed for the nontrivial solutions, yielding explicit expressions of the existence and the stability conditions in terms of the detuning parameter. Numerical examples clearly show the effects of tension fluctuations and translating speeds on the amplitudes of dynamic responses, the corresponding existence domains and the stability of the solutions. It is also demonstrated that the stability domains of the nontrivial solutions are different from those corresponding to elastic models.

Influence of the Internal State of a Maxwell Damper on Free Critically Damped Vibrations

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
M. B. Rubin
Keyword(s):  
Physical Model ◽  
Initial Value Problems ◽  
Internal State ◽  
Initial Value ◽  
Zero Velocity ◽  
In Series ◽  
Standard Linear Solid ◽  
Standard Linear

A Maxwell damper with a damper spring in series with a viscous dashpot is a more physical model than a viscous dashpot because the Maxwell damper models the elasticity of the connecting links of the viscous dashpot. The system of a main spring in parallel with a Maxwell damper is known as the standard linear solid (SLS) in viscoelasticity. The response of this SLS attached to a mass for standard initial value problems: displacement (nonzero displacement with zero velocity) and velocity (zero displacement with nonzero velocity) have been analyzed a few times in the literature. However, different authors present different conclusions about the importance of modeling the damper spring. None of these authors have explored the influence of the initial internal state of the damper spring. Here it is shown that the initial internal state of the damper spring can significantly influence the response for both displacement and velocity initial value problems.

Storage and loss stiffnesses and moduli as determined by dynamic nanoindentation

2009 ◽  
Vol 24 (3) ◽  
pp. 863-871 ◽  
Author(s):  
Wendelin J. Wright ◽  
W.D. Nix
Keyword(s):  
Physical Model ◽  
Composite System ◽  
Storage And Loss Moduli ◽  
In Series ◽  
Standard Linear Solid ◽  
Standard Linear ◽  
Load Frame ◽  
Composite Response ◽  
Dynamic Nanoindentation

The storage and loss stiffnesses for the composite response of the sample, indenter, and load frame during dynamic nanoindentation are derived. In the first part of the analysis, no physical model is assigned to the composite system. It is shown that this case is equivalent to the conventional nanoindentation analysis. In the second part of the analysis, the sample is modeled as a standard linear solid in series with the indenter and load frame. The results for the storage and loss stiffnesses as computed by the two methods differ by at most ∼3% for the elastomeric system under consideration. Results for the storage and loss moduli are also similar. The relative merits and weaknesses of each analysis are discussed.

scholarly journals Insights into the Multilevel Structural Characterization and Adsorption Mechanism of Sinogastromyzon szechuanensis Sucker on the Rough Surface

Life ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 952
Author(s):  
Qian Cong ◽  
Jin Xu ◽  
Jiaxiang Fan ◽  
Tingkun Chen ◽  
Shaofeng Ru
Keyword(s):  
Surface Roughness ◽  
Spectral Function ◽  
Rough Surface ◽  
Structural Characterization ◽  
Adsorption Mechanism ◽  
Rough Surfaces ◽  
Experimental Results ◽  
Adsorption Performance ◽  
Multilevel Structure ◽  
New Type

The present study investigates the adsorption performance and adsorption mechanism of Sinogastromyzon szechuanensis on different rough surfaces. The different positions of the sucker surface of Sinogastromyzon szechuanensis were observed by adopting the stereomicroscope and SEM. The observed results showed that the sucker of Sinogastromyzonszechuanensis had a multilevel structure of villi and groove. The anterior and posterior of Sinogastromyzonszechuanensis had different microscopic morphologies. The surface roughness of the adsorption substrate ranged from 7 μm to 188 μm. Adsorption strength of Sinogastromyzonszechuanensis and the conventional sucker on different rough surfaces were measured by a purposely designed device. The results showed that the back of Sinogastromyzonszechuanensis mainly provided the adsorption strength. The adsorption strength of the conventional sucker gradually decreased with surface roughness increasing, but the adsorption strength of Sinogastromyzon szechuanensis had not changed significantly. Based on the experimental results, the adsorption mechanism of Sinogastromyzonszechuanensis on the surface with different roughness was analyzed by the spectral function. The Sinogastromyzonszechuanensis sucker with a multilevel structure worked well on the rough surface, which led to Sinogastromyzonszechuanensis with a good sealing on the rough surface. The present work could help to develop a new type of sucker with effective adsorption performance on a rough surface to meet the needs of the engineering field.

Pond Treatment of Rettery Wastewaters

1987 ◽  
Vol 19 (12) ◽  
pp. 79-83
Author(s):  
K. Bartoszewski ◽  
A. Bilyk
Keyword(s):  
Activated Sludge ◽  
Treatment Process ◽  
New Technology ◽  
Treatment Plant ◽  
Anaerobic Treatment ◽  
Cod Removal ◽  
Experimental Results ◽  
Aerobic Conditions ◽  
Aerobic Stabilization ◽  
In Series

Rettery wastewaters were treated in anaerobic and aerobic ponds. Anaerobic treatment yielded efficiencies of BOD5 and COD removal as low as 20%. The treatment process conducted under aerobic conditions in aerated and stabilizing ponds arranged in series took from 18 to 20 days and gave efficiencies of BOD5 and COD removal amounting to 90%. The experimental results were interpreted by virtue of the Eckenfelder equation. Excess activated sludge was subjected to aerobic stabilization in a separate tank. A new technology was suggested for the existing obsolete industrial treatment plant.

scholarly journals Stable and Efficient Modeling of Anelastic Attenuation in Seismic Wave Propagation

2012 ◽  
Vol 12 (1) ◽  
pp. 193-225 ◽  
Author(s):  
N. Anders Petersson ◽  
Björn Sjögreen
Keyword(s):  
Wave Equation ◽  
Finite Difference ◽  
Half Space ◽  
Material Model ◽  
Second Order ◽  
Finite Difference Approximation ◽  
Difference Approximation ◽  
Space Problem ◽  
Standard Linear Solid ◽  
Standard Linear

AbstractWe develop a stable finite difference approximation of the three-dimensional viscoelastic wave equation. The material model is a super-imposition of N standard linear solid mechanisms, which commonly is used in seismology to model a material with constant quality factor Q. The proposed scheme discretizes the governing equations in second order displacement formulation using 3N memory variables, making it significantly more memory efficient than the commonly used first order velocity-stress formulation. The new scheme is a generalization of our energy conserving finite difference scheme for the elastic wave equation in second order formulation [SIAM J. Numer. Anal., 45 (2007), pp. 1902-1936]. Our main result is a proof that the proposed discretization is energy stable, even in the case of variable material properties. The proof relies on the summation-by-parts property of the discretization. The new scheme is implemented with grid refinement with hanging nodes on the interface. Numerical experiments verify the accuracy and stability of the new scheme. Semi-analytical solutions for a half-space problem and the LOH.3 layer over half-space problem are used to demonstrate how the number of viscoelastic mechanisms and the grid resolution influence the accuracy. We find that three standard linear solid mechanisms usually are sufficient to make the modeling error smaller than the discretization error.

Color Reproduction Accuracy Promotion of 3D-Printed Surfaces Based on Microscopic Image Analysis

2019 ◽  
Vol 34 (01) ◽  
pp. 2054004 ◽  
Author(s):  
Xiaochun Wang ◽  
Chen Chen ◽  
Jiangping Yuan ◽  
Guangxue Chen
Keyword(s):  
Surface Roughness ◽  
Image Analysis ◽  
Three Dimensional ◽  
Prediction Method ◽  
Chromatic Aberration ◽  
Optimization Methods ◽  
Experimental Models ◽  
Microscopic Image ◽  
Color Reproduction ◽  
Microscopic Image Analysis

Full-color three-dimensional (3D) printing technology is a powerful process to manufacture intelligent customized colorful objects with improved surface qualities; however, poor surface color optimization methods are the main impeding factors for its commercialization. As such, the paper explored the correlation between microstructure and color reproduction, then an assessment and prediction method of color optimization based on microscopic image analysis was proposed. The experimental models were divided into 24-color plates and 4-color cubes printed by ProJet 860 3D printer, then impregnated according to preset parameters, at last measured by a spectrophotometer and observed using both a digital microscope and a scanning electron microscope. The results revealed that the samples manifested higher saturation and smaller chromatic aberration ([Formula: see text]) after postprocessing. Moreover, the brightness of the same color surface increased with the increasing soaked surface roughness. Further, reduction in surface roughness, impregnation into surface pores, and enhancement of coating transparency effectively improved the accuracy of color reproduction, which could be verified by the measured values. Finally, the chromatic aberration caused by positioning errors on different faces of the samples was optimized, and the value of [Formula: see text] for a black cube was reduced from 8.12 to 0.82, which is undetectable to human eyes.

scholarly journals Asymptotic behaviour for the vibrations modeled by the standard linear solid model with a thermal effect

2013 ◽  
Vol 399 (2) ◽  
pp. 472-479 ◽  
Author(s):  
Margareth S. Alves ◽  
Celene Buriol ◽  
Marcio V. Ferreira ◽  
Jaime E. Muñoz Rivera ◽  
Mauricio Sepúlveda ◽  
...  
Keyword(s):  
Asymptotic Behaviour ◽  
Thermal Effect ◽  
Solid Model ◽  
Standard Linear Solid Model ◽  
Standard Linear Solid ◽  
Standard Linear

An Active Equalizer for Serially Connected Lithium-Ion Battery Cells

2013 ◽  
Vol 732-733 ◽  
pp. 809-812 ◽  
Author(s):  
Hong Rui Liu ◽  
Chao Ying Xia
Keyword(s):  
Lithium Ion Battery ◽  
Lithium Ion ◽  
State Of Charge ◽  
Experimental Results ◽  
Battery Cell ◽  
Charging Current ◽  
In Series ◽  
Battery Cells

This paper proposes an equalizer for serially connected Lithium-ion battery cells. The battery cell with the lowest state of charge (SOC) is charged by the equalizer during the process of charging and discharging, and the balancing current is constant and controllable. Three unbalanced lithium-ion battery cells in series are selected as the experimental object by this paper. The discharging current under a certain UDDS and 20A charging current are used to complete respectively one time balancing experiment of discharging and charging to the three lithium-ion battery cells. The validity of the balancing strategy is confirmed in this paper according to the experimental results.

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