scholarly journals A Criterion for the Effective Work of Adhesion in Loading and Unloading of Adhesive Soft Solids from Rough Surfaces

2021 ◽  
Vol 69 (1) ◽  
Author(s):  
Antonio Papangelo ◽  
Michele Ciavarella
Keyword(s):  
Experimental Data ◽  
Intrinsic Property ◽  
Atomic Scale ◽  
Work Of Adhesion ◽  
Simple Criterion ◽  
Effective Work ◽  
Soft Solids ◽  
Soft Spheres ◽  
Loading And Unloading ◽  
Rule Out

AbstractRecently, Dalvi and co-authors have shown detailed experimental data of adhesion of soft spheres with rough substrates with roughness measured down to almost the atomic scale, finding that the Persson and Tosatti theory gave satisfactory predictions of the apparent work of adhesion during loading, once the increase of the surface area due to roughness is correctly computed at extremely small scales. We show that unloading data would show similar correlation with the Persson–Tosatti’s simple criterion, but for a much larger effective work of adhesion, which therefore becomes not an “intrinsic” property. This suggests either strong hysteresis even at apparently very low peeling velocities or the need to use a criterion that has different behavior during loading and unloading. We attempt this inspired by the results of Guduru for a simple case of axisymmetric waviness, and a much better fit of the experimental data by Dalvi and co-authors is obtained using the entire set of data at loading and unloading, even assuming a single work of adhesion value. However, we cannot rule out that both (viscoelastic) and (roughness-induced) enhancement effects coexist in these data.

From Adatom Migration to Chemical Kinetics: Models for MBE, Mombe and MOCVD

1993 ◽  
Vol 312 ◽  
Author(s):  
D. D. Vvedensky ◽  
T. Shitarat ◽  
P. Smilauer ◽  
T. Kaneko ◽  
A. Zangwill
Keyword(s):  
Experimental Data ◽  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Chemical Vapor ◽  
High Energy ◽  
Atomic Scale ◽  
Basic Model ◽  
Mobile Species ◽  
Local Environments ◽  
Starting Point

AbstractThe application of Monte Carlo simulations to various epitaxial growth methods is examined from the standpoint of incorporating only those kinetics processes that are required to explain experimental data. A basic model for molecular-beam epitaxy (MBE) is first introduced and some of the features that make it suitable for describing atomic-scale processes are pointed out. Extensions of this model for cases where the atomic constituents of the growing surface are delivered in the form of heteroatomic molecules are then considered. The experimental scenarios that is discussed is the homoepitaxy of GaAs(001) using metalorganic molecular-beam epitaxy (MOMBE) with triethylgallium (TEG) and precursors and using MOCVD with trimethylgallium (TMG). For MOMBE, the comparisons between simulations and experiments are based on reflection high-energy electron diffraction intensities, by analogy with comparisons made for MBE, while for metalorganic chemical vapor deposition (MOCVD) the simulations are compared to in situ glancingincidence x-ray scattering measurements. In both of these cases, the inclusion of a second mobile species to represent the precursor together with various rules for the decomposition of this molecule (in terms of rates and local environments) with be shown to provide a useful starting point for explaining the general trends in the experimental data and for further refinements of the model.

Buckling of Viscoelastic Columns. Part II: Constant Deformation Rate Buckling

1985 ◽  
Vol 58 (1) ◽  
pp. 164-175 ◽  
Author(s):  
Shau-Chew Wang ◽  
Eberhard A. Meinecke
Keyword(s):  
Experimental Data ◽  
Secondary Structure ◽  
Carbon Black ◽  
Deformation Rate ◽  
Linear Viscoelasticity ◽  
Theoretical Development ◽  
Gravitational Effects ◽  
Loading And Unloading ◽  
Constant Deformation ◽  
Lower Carbon

Abstract The buckling of viscoelastic columns has been considered from both a theoretical and an experimental perspective. The fact that buckling occurs at relatively low strain where the SBR is nearly linearly viscoelastic allowed several simplifications in the theoretical development, leading to closed form predictions of the loading and unloading curves. This treatment neglects gravitational effects and carbon secondary structure effects and fits the experimental data best at HAF loadings around 30 phr. At lower carbon black loadings, the gravitational effects caused the experimental Euler load to be less than predicted from linear viscoelasticity theory, while at higher carbon black loadings, the carbon black structure led to higher Euler loads than predicted.

Adhesive and normal stress-dependent dynamic friction of a gelatin hydrogel

2021 ◽  
pp. 135065012110446
Author(s):  
Nitish Sinha ◽  
Arun Kumar Singh ◽  
Vinit Gupta ◽  
Jitendra Kumar Katiyar
Keyword(s):  
Experimental Data ◽  
Normal Stress ◽  
Scaling Law ◽  
Shear Velocity ◽  
Friction Model ◽  
Dynamic Friction ◽  
Practical Applications ◽  
Soft Solids ◽  
Gelatin Hydrogel ◽  
Stress Dependent

Adhesion and friction of soft solids on hard surfaces are the important properties for a variety of practical applications. In the present study, Coulomb's law of friction is used for characterizing adhesive friction as well as normal stress-dependent dynamic friction of a gelatin hydrogel on a fixed glass surface. The experimental data, concerning normal stress-dependent dynamic friction of different shear velocity, are obtained from literature. It is observed that both components of friction increase with shear velocity. More importantly, the scaling law shows that adhesive stress varies almost linearly with corresponding coefficient of friction of the hydrogel. A dynamic friction model is also used to analyze the same experimental data to predict a negative normal stress at which dynamic friction reduces to zero, and this result matches closely with the experimental value.

Effect of the ageing on the dissipative properties of getinacks subjected to repeated static loading

2014 ◽  
Vol 11 (6) ◽  
pp. 589-596
Author(s):  
Valesyan Shant
Keyword(s):  
Experimental Data ◽  
Experimental Investigation ◽  
Temperature Field ◽  
Energy Dissipation ◽  
Hysteresis Loop ◽  
Static Loading ◽  
Applied Load ◽  
Effect Of Temperature ◽  
Loading And Unloading

The effect of ageing on the dissipative properties of getinacks subjected to repeated static loading has been investigated. Specimens were tested at the age of 1, 4, and 8 years. The approximation of experimental data is done, and the energy of dissipation is calculated. Based on the investigation of getinacks manufactured by the technology of regulated thermo-pressing, this technology can be recommended for the manufacturing of appropriate products.The results of experimental investigation of the effect of temperature field on the dissipative properties of layered getinacks widely applicable in electrical manufacturing, electronics and microelectronics are considered in this paper. The approximation of the experimentally obtained dependences between σ and ε for the loading (→) and unloading (←) parts of the hysteresis loop are calculated and plotted. The factor of energy dissipation is defined. Estimated that the temperature field affects the dissipative properties of the layered getinacks and that effect is depending on the value of applied load cyclically acting on the material.

Molecular Dynamics Simulation of a Rigid Sphere Indenting a Copper Substrate

2012 ◽  
Author(s):  
Ding Jia ◽  
Longqiu Li ◽  
Andrey Ovcharenko ◽  
Wenping Song ◽  
Guangyu Zhang
Keyword(s):  
Molecular Dynamics ◽  
Md Simulation ◽  
Copper Substrate ◽  
Three Dimensional ◽  
Atomic Scale ◽  
Dynamics Simulation ◽  
Rigid Sphere ◽  
Displacement Curve ◽  
Loading And Unloading ◽  
Force Displacement

Three-dimensional molecular dynamics (MD) simulation is used to study the atomic-scale indentation process of a spherical diamond tip in contact with a copper substrate. In the indentation simulations, the force-displacement curve is obtained and compared with a modified elastic solution of Hertz. The contact area under different indentation depths is also investigated. The force-displacement curve under different maximum indentation depths is obtained to investigate elastic-plastic deformation during the loading and unloading processes.

Density Functional Theory in Surface Science and Heterogeneous Catalysis

MRS Bulletin ◽  
2006 ◽  
Vol 31 (9) ◽  
pp. 669-674 ◽  
Author(s):  
J.K. Nørskov ◽  
M. Scheffler ◽  
H. Toulhoat
Keyword(s):  
Experimental Data ◽  
Density Functional Theory ◽  
Heterogeneous Catalysis ◽  
Surface Science ◽  
Density Functional ◽  
Catalytic Reactions ◽  
Solid Surfaces ◽  
Atomic Scale ◽  
Functional Theory ◽  
Insight Into

AbstractSolid surfaces are used extensively as catalysts throughout the chemical industry, in the energy sector, and in environmental protection. Recently, density functional theory has started providing new insight into the atomic-scale mechanisms of heterogeneous catalysis, helping to interpret the large amount of experimental data gathered during the last decades. This article shows how density functional theory can be used to describe the state of the surface during reactions and the rate of catalytic reactions. It will also show how we are beginning to understand the variation in catalytic activity from one transition metal to the next. Finally, the prospects of using calculations to guide the development of new catalysts in industry will be discussed.

scholarly journals Experiments on the symmetry of length and time

2021 ◽  
Author(s):  
Li Chunhong
Keyword(s):  
Experimental Data ◽  
Quantum Mechanics ◽  
General Theory ◽  
Piezoelectric Sensor ◽  
Atomic Scale ◽  
Theory Of Relativity ◽  
General Theory Of Relativity ◽  
Speed Of Light ◽  
Time Coordinate ◽  
Time Position

Abstract The F - t curve obtained from the process of applying and releasing force to the piezoelectric sensor shows that in the atomic scale, the time coordinate is equivalent to the position coordinate. The time-position coordinate relationship calculated by the experimental data is consistent with the geometric unit obtained in the general theory of relativity, thus the experiment verifies the symmetry of length and time,and connection between the microscopic - quantum mechanics and the macroscopic - general theory of relativity, and a new method for calculating the speed of light is obtained.

scholarly journals Sit-and-Wait Strategies in Dynamic Visual Search

2003 ◽  
Vol 14 (4) ◽  
pp. 309-314 ◽  
Author(s):  
Adrian von Mühlenen ◽  
Hermann J. Müller ◽  
Dagmar Müller
Keyword(s):  
Experimental Data ◽  
Visual Search ◽  
Inhibition Of Return ◽  
Search Task ◽  
Visual Search Task ◽  
Dynamic Condition ◽  
Static Condition ◽  
Limited Region ◽  
Rule Out

The role of memory in visual search has lately become a controversial issue. Horowitz and Wolfe (1998) observed that performance in a visual search task was little affected by whether the stimuli were static or randomly relocated every 111 ms. Because a memory-based mechanism, such as inhibition of return, would be of no use in the dynamic condition, Horowitz and Wolfe concluded that memory is likewise not involved in the static condition. However, Horowitz and Wolfe could not effectively rule out the possibility that observers adopted a different strategy in the dynamic condition than in the static condition. That is, in the dynamic condition observers may have attended to a subregion of the display and waited for the target to appear there (sit-and-wait strategy). This hypothesis is supported by experimental data showing that performance in their dynamic condition does not differ from performance in another dynamic condition in which observers are forced to adopt a sit-and-wait strategy by being presented with a limited region of the display only.

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