scholarly journals Numerical estimation of interface roughness effect on upscaled elastic properties of layered media

2020 ◽  
pp. 225-240
Author(s):  
Т.С. Хачкова ◽  
В.В. Лисица ◽  
Д.Р. Колюхин ◽  
Г.В. Решетова
Keyword(s):  
Elastic Properties ◽  
Numerical Algorithm ◽  
Elastic Moduli ◽  
Numerical Study ◽  
Layered Media ◽  
Interface Roughness ◽  
Numerical Estimation ◽  
Roughness Effect ◽  
Equivalent Models ◽  
Different Types

Представлено численное исследование влияния шероховатости границ раздела в слоистой среде на эффективные упругие свойства тонкослоистой среды. Предложен алгоритм построения статистически эквивалентных моделей слоистых сред двух различных типов. Первый тип включает в себя модели с постоянными упругими параметрами, но с шероховатой границей раздела. Второй тип состоит из моделей с плоскими границами раздела, но с параметрами, задаваемыми случайными величинами. При этом распределение упругих параметров в моделях второго типа (средние значения и ковариационная матрица) однозначно определяется шероховатостью границ раздела (длина корреляции и стандартное отклонение) в моделях первого типа. We discuss a numerical study of the interface roughness effect on elastic moduli of an upscaled model of layered media. We propose a numerical algorithm to construct statistically equivalent models of two different types. The first type includes the models with constant elastic moduli but with rough interfaces. The second type consists of models with flat interfaces but with stochastic elastic moduli. It is shown that the distribution of the elastic moduli for the models of the second type is uniquely determined by the interface roughness in the models of the first type.

scholarly journals Elastic Properties of Statistically Equivalent Materials With Varying Individual Grain Orientations

1995 ◽  
Vol 25 (1) ◽  
pp. 17-24 ◽  
Author(s):  
H. Kiewel ◽  
H. J. Bunge ◽  
L. Fritsche
Keyword(s):  
Elastic Properties ◽  
Displacement Field ◽  
Elastic Moduli ◽  
Local Deformation ◽  
Deformation Field ◽  
Copper Metal ◽  
Bcc Lattice ◽  
Real Material ◽  
Different Types ◽  
Grain Orientations

The elastic properties of copper metal with different individual grain orientations exhibiting the same texture are determined. We simulate the real material by two different types of clusters. The first one consists of 365 cubic grains, the second cluster is an arrangement of 181 Wigner-Seitz cells of a body centred cubic (bcc)-lattice. For each type of cluster we let the local grain orientations vary. The displacement field inside these aggregates as a result of a homogeneous deformation acting on the surface of the clusters is calculated. Although the resulting local deformation field for different individual grain orientations varies strongly, the macroscopic elastic moduli are in the frame of this simulation identical for any cluster of the same type, as it has to be for statistically equivalent materials.

scholarly journals Polystyrene-Based Nanocomposites with Different Fillers: Fabrication and Mechanical Properties

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2457
Author(s):  
Olga A. Moskalyuk ◽  
Andrey V. Belashov ◽  
Yaroslav M. Beltukov ◽  
Elena M. Ivan’kova ◽  
Elena N. Popova ◽  
...  
Keyword(s):  
Elastic Properties ◽  
Elastic Moduli ◽  
Spherical Particles ◽  
Linear Elastic ◽  
Rigid Particles ◽  
Different Types ◽  
Non Linear ◽  
Multi Walled Carbon Nanotubes ◽  
Carbon Fillers ◽  
Walled Carbon Nanotubes

The paper presents a comprehensive analysis of the elastic properties of polystyrene-based nanocomposites filled with different types of inclusions: small spherical particles (SiO2 and Al2O3), alumosilicates (montmorillonite, halloysite natural tubules and mica), and carbon nanofillers (carbon black and multi-walled carbon nanotubes). Block samples of composites with different filler concentrations were fabricated by melt technology, and their linear and non-linear elastic properties were studied. The introduction of more rigid particles led to a more profound increase in the elastic modulus of a composite, with the highest rise of about 80% obtained with carbon fillers. Non-linear elastic moduli of composites were shown to be more sensitive to addition of filler particles to the polymer matrix than linear ones. A non-linearity modulus βs comprising the combination of linear and non-linear elastic moduli of a material demonstrated considerable changes correlating with those of the Young’s modulus. The changes in non-linear elasticity of fabricated composites were compared with parameters of bulk non-linear strain waves propagating in them. Variations of wave velocity and decay decrement correlated with the observed enhancement of materials’ non-linearity.

On: “RECENT TECHNIQUES FOR DETERMINATION OF IN SITU ELASTIC PROPERTIES AND MEASUREMENT OF MOTION AMPLIFICATION IN LAYERED MEDIA,” BY R. J. SWAIN (GEOPHYSICS, APRIL, 1962, PP. 237–241).

Geophysics ◽  
1963 ◽  
Vol 28 (1) ◽  
pp. 112-113 ◽  
Author(s):  
Tsvi Meidav
Keyword(s):  
Elastic Properties ◽  
Seismic Wave ◽  
Elastic Moduli ◽  
Layered Media ◽  
Small Error ◽  
Elastic Parameters ◽  
Dynamic Elastic Properties

Swain points out that seismic techniques have been used for determination of elastic parameters in unconsolidated materials as well as in consolidated ones. It must be pointed out that relationships between elastic moduli and longitudinal and shear velocities are not entirely valid for soil or other unconsolidated matter, as those are not truly elastic. An exception to this statement may be made with a small error when it is desirable to determine the dynamic elastic properties of the material at the frequency of the seismic wave. Such a determination might be useful in testing a foundation for a vibrating machinery or a runway.

A Non-Cooperative Game Analysis of Competition between Content Providers in the Internet Market

2019 ◽  
Vol 15 (1) ◽  
pp. 88-104 ◽  
Author(s):  
M'hamed Outanoute ◽  
Hamid Garmani ◽  
Mohamed Baslam ◽  
Rachid El Ayachi ◽  
Belaid Bouikhalene
Keyword(s):  
Quality Of Service ◽  
Detailed Analysis ◽  
Cooperative Game ◽  
Price Of Anarchy ◽  
Numerical Study ◽  
Pure Nash Equilibrium ◽  
Game Analysis ◽  
Different Types ◽  
Internet Market

In internet market, content providers (CPs) continue to play a primordial role in the process of accessing different types of data. Competition in this area is fierce; customers are looking for providers that offer them good content (credibility of content and quality of service) with a reasonable price. In this work, the authors analyze this competition between CPs and the economic influence of their strategies on the market. The authors formulate their problem as a non-cooperative game among multiple CPs for the same market. Through a detailed analysis, the researchers prove uniqueness of a pure Nash Equilibrium (NE). Furthermore, a fully distributed algorithm to converge on the NE point is presented. In order to quantify how efficient the NE point is, a detailed analysis of the Price of Anarchy (PoA) is adopted to ensure the performance of the system at equilibrium. Finally, an extensive numerical study is provided to describe the interactions between CPs and to point out the importance of quality of service (QoS) and credibility of content in the market.

scholarly journals Sensitivity of Ultrasonic Coda Wave Interferometry to Material Damage—Observations from a Virtual Concrete Lab

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4033
Author(s):  
Claudia Finger ◽  
Leslie Saydak ◽  
Giao Vu ◽  
Jithender J. Timothy ◽  
Günther Meschke ◽  
...  
Keyword(s):  
Elastic Moduli ◽  
Concrete Specimen ◽  
Coda Wave ◽  
Velocity Change ◽  
Damage Scenarios ◽  
Different Types ◽  
Source Signal ◽  
The Impact ◽  
Structural Scale ◽  
Coda Wave Interferometry

Ultrasonic measurements are used in civil engineering for structural health monitoring of concrete infrastructures. The late portion of the ultrasonic wavefield, the coda, is sensitive to small changes in the elastic moduli of the material. Coda Wave Interferometry (CWI) correlates these small changes in the coda with the wavefield recorded in intact, or unperturbed, concrete specimen to reveal the amount of velocity change that occurred. CWI has the potential to detect localized damages and global velocity reductions alike. In this study, the sensitivity of CWI to different types of concrete mesostructures and their damage levels is investigated numerically. Realistic numerical concrete models of concrete specimen are generated, and damage evolution is simulated using the discrete element method. In the virtual concrete lab, the simulated ultrasonic wavefield is propagated from one transducer using a realistic source signal and recorded at a second transducer. Different damage scenarios reveal a different slope in the decorrelation of waveforms with the observed reduction in velocities in the material. Finally, the impact and possible generalizations of the findings are discussed, and recommendations are given for a potential application of CWI in concrete at structural scale.

Bejan’s Constructal Theory Analysis of Gas-Liquid Cooled Finned Modules

2011 ◽  
Vol 133 (7) ◽  
Author(s):  
Giulio Lorenzini ◽  
Simone Moretti
Keyword(s):  
Thermal Behavior ◽  
Heat Exchangers ◽  
High Performance ◽  
Numerical Study ◽  
Constructal Theory ◽  
Electronic Components ◽  
Theory Analysis ◽  
Pressure Losses ◽  
Different Types ◽  
Overall Performance

High performance heat exchangers represent nowadays the key of success to go on with the trend of miniaturizing electronic components as requested by the industry. This numerical study, based on Bejan’s Constructal theory, analyzes the thermal behavior of heat removing fin modules, comparing their performances when operating with different types of fluids. In particular, the simulations involve air and water (as representative of gases and liquids), to understand the actual benefits of employing a less heat conductive fluid involving smaller pressure losses or vice versa. The analysis parameters typical of a Constructal description (such as conductance or Overall Performance Coefficient) show that significantly improved performances may be achieved when using water, even if an unavoidable increase in pressure losses affects the liquid-refrigerated case. Considering the overall performance: if the parameter called Relevance tends to 0, air prevails; if it tends to 1, water prevails; if its value is about 0.5, water prevails in most of the case studies.

Measurement and Analysis of Triboelectric Surface Charge

2021 ◽  
Vol 30 (1/2) ◽  
pp. 7-11
Author(s):  
Jinhong PARK ◽  
Jinhyeok CHOI ◽  
Sang Hyeok PARK ◽  
Minbaek LEE
Keyword(s):  
Electron Transfer ◽  
Charge Transfer ◽  
Surface Properties ◽  
Elastic Moduli ◽  
Surface Charges ◽  
Contact Electrification ◽  
Measurement And Analysis ◽  
Different Types ◽  
Triboelectric Charging ◽  
Method Of Measurement

Contact electrification occurs when two isolated objects come into contact. Such a phenomenon led humans to first realization of the existence of electricity. Until now, the main causes of the triboelectric charging phenomenon have generally been thought to be the transfer of electrons, ions, and materials. This article, however, is limited to electron transfer on the surface, which is regarded as a general case not limited to specific situations. The contact between two objects occurs between the two surfaces; therefore, the surface properties of the material under examination are the most important properties in triboelectric charge transfer. The surface properties may include the types of materials in contact, their energy states, the roughnesses of their surfaces, and their elastic moduli. In this regard, we introduce here the current understanding of the energy band structures involved in the different types of materials, the method of measurement, an analysis of surface charges, and related applications.

Numerical Study of an Impact Oscillator

1995 ◽  
Author(s):  
Kannan Marudachalam ◽  
Faruk H. Bursal
Keyword(s):  
Dynamical Systems ◽  
Numerical Algorithm ◽  
Initial Conditions ◽  
Numerical Study ◽  
Harmonic Excitation ◽  
General Purpose ◽  
Constrained Systems ◽  
Global Dynamics ◽  
Impact Oscillator ◽  
Stick Slip

Abstract Systems with discontinuous dynamics can be found in diverse disciplines. Meshing gears with backlash, impact dampers, relative motion of components that exhibit stick-slip phenomena axe but a few examples from mechanical systems. These form a class of dynamical systems where the nonlinearity is so severe that analysis becomes formidable, especially when global behavior needs to be known. Only recently have researchers attempted to investigate such systems in terms of modern dynamical systems theory. In this work, an impact oscillator with two-sided rigid constraints is used as a paradigm for studying the characteristics of discontinuous dynamical systems. The oscillator has zero stiffness and is subjected to harmonic excitation. The system is linear without impacts. However, the impacts introduce nonlinearity and dissipation (assuming inelastic impacts). A numerical algorithm is developed for studying the global dynamics of the system. A peculiar type of solution in which the trajectories in phase space from a certain set of initial conditions merge in finite time, making the dynamics non-invertible, is investigated. Also, the effect of “grazing,” a behavior common to constrained systems, on the dynamics of the system is studied. Based on the experience gained in studying this system, the need for an efficient general-purpose numerical algorithm for solving discontinuous dynamical systems is motivated. Investigation of stress, vibration, wear, noise, etc. that are associated with impact phenomena can benefit greatly from such an algorithm.

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