Effects Of Elastic Properties Research Articles

Coupled Model of Multi-Mechanistic Gas–Water Transport Behavior in Tight Shale

In this work, the gas–water production period in a shale gas reservoir is divided into two stages: the gas–water two-phase flow dominates at Stage I, while at Stage II, the flows are controlled by the desorbed gas and water in the adsorbed phase. The evolution models of porosity and permeability incorporate the swelling strains induced by the combined gas and water sorption. A coupled model of multi-mechanistic gas–water transport behavior in tight shale was proposed and numerically solved. Results show that at Stage I, rapid gas production is observed due to the flows of free gas and desorbed gas production, followed by a decline in the production profile toward the critical water saturation point. During Stage II, the gas production rate is influenced by the residual water content controlled by the flow of water in the adsorbed phase. The effect of sorption-induced matrix shrinkage strain will take the leading role at the late production stage. In addition, the effects of elastic properties, initial permeability, and diffusion time on the permeability ratio and gas/water production profiles are discussed. These results provide a framework for analyzing gas/water transport behavior and water retention behavior in tight shale.

P‐43: Application of High Stiffness Glass Substrate for Multi‐Functional Large Area Displays

Demand of large size flat panel displays are emerging. For upcoming displays, extra features are demanded in addition to the visual performance. One of the attracting features is the combination with an acoustic function. To utilize the display panel as a speaker, glass substrate plays important role to improve its acoustic quality. In this study, the effect of elastic property on display panel performance was investigated.

The Effect of Elastic Properties on Indentation Test for Multi-layered Materials

The Effect of Elastic Properties on Indentation Test for Multi-layered Materials

Poisson effect driven anomalous lattice expansion in metal nanoshells

Surface stress can have profound effects on nanoscale materials and can lead to a contraction of the lattice in nanoparticles to compensate for the under-coordination of the surface atoms. The effect of elastic properties like Poisson's ratio can be accentuated in lower dimensional systems. The current study focuses on hollow metal nanoshells (MNSs), wherein there is interplay between the surface stresses existing in the inner and outer surfaces. Using a two scale computational method and transmission electron microscopy, we not only show a lattice expansion (in the radial direction) due to purely surface stress effects in a metallic system but also discover anomalous lattice expansion in the case of very thin walled MNSs. We argue that this effect, wherein the stress in the outer surface causes expansion in the radial lattice parameter (instead of compression), is a Poisson effect driven phenomenon. Although Ni nanoshells are used as an illustrative system for the studies, we generalize this effect for all metal nanoshells.

Precise positioning of cancerous cells on PDMS substrates with gradients of elasticity.

In this work the novel method to create PDMS substrates with continuous and discrete elasticity gradients of different shapes and dimensions over the large areas was introduced. Elastic properties of the sample were traced using force spectroscopy (FS) and quantitative imaging (QI) mode of atomic force microscopy (AFM). Then, fluorescence microscopy was applied to investigate the effect of elastic properties on proliferation of bladder cancer cells (HCV29). Obtained results show that cancerous cells proliferate significantly more effective on soft PDMS, whereas the stiff one is almost cell-repellant. This strong impact of substrate elasticity on cellular behavior is driving force enabling precise positioning of cells.

Effect of elastic properties on the propagation of gelled and in-situ gelled acids in carbonate cores

Abstract Polymer-based acids exhibit some viscoelastic properties. Therefore, the objectives of this study are to determine the elastic and viscous properties of these acids, how these properties change as the acid reacts with carbonate formations, and their effect on the propagation of the acid inside 20-in. long carbonate cores. Live gelled and in-situ gelled acids had weak elastic properties, while partially neutralized (pH 3.2) in-situ gelled acid had strong elastic properties. Polymer filter cake was observed for the cores that were treated with gelled acid while the cores that were treated with in-situ gelled acids did not form this filter-cake. In-situ gelled acid formed a thin layer of gel that minimized leakoff, which prevented the formation of filter cake. For gelled acid, the polymer filter cake reduced the core permeability to zero. The wormhole obtained in the case of gelled acid was nearly linear and thinner than those created by in-situ gelled acid. The strong elastic properties enhanced the ability to get the gel to remain around the wormhole, which forced the next acid stage to change its direction.

Effect of elastic properties of material composition on the fracture response of transversely graded ceramic/metal material

Abstract The effect of material composition and their elastic properties on the fracture behavior of a transversely graded material is investigated. A single edge notched specimen machined from Ti/TiB graded material with a crack perpendicular to the gradient direction is subjected to three-point bending and the displacement fields on both faces of the sample, Ti and TiB-rich, are obtained using full-field 3D digital image correlation. These displacement fields, along with the asymptotic displacement equation, are used to extract fracture parameters using an overdeterministic least square approach. The displacement fields from a 3D finite element model are also used to calculate the stress intensity factor at each layer throughout the thickness. The variation of stress intensity factor in the gradient (thickness) direction is presented as a function of the elastic modulus of the material. A simple semi-empirical model is also proposed to calculate the stress intensity factor as a function of the material elastic properties at any section along the thickness direction, and to predict the effective fracture toughness of the material.

Using a scale-bridging technique to determine the effect of elastic properties on stress distribution around the femoral stem of an artificial hip joint with a simplified geometry

A scale-bridging technique was used to investigate the effect of the elastic properties of β-Ti alloys on the stress distribution around the femoral stem of an artificial hip joint with a simplified geometry when under an external loading. The anisotropic elastic constants of single-crystalline β-Ti alloys (TN1: Ti-18.75 at% Nb, TN2: Ti-37.5 at% Nb, and TN3: Ti-43.75 at% Nb) were calculated using an ab-initio technique that was based on density functional theory calculation. The single-crystalline elastic constants calculated via the ab-initio technique were used to calculate the elastic constants of polycrystal β-Ti alloys using an elastic selfconsistent scheme. Finite element analysis based on the elastic constants of polycrystalline β-Ti alloys for a femoral stem was conducted to calculate the above-mentioned stress distribution. The model system consisting of a TN1 alloy exhibited a relatively high level of von Mises stress on the surface of cancellous and cortical bones compared to model systems consisting of TN2, TN3 alloys and commercial biomaterials (Ti-6Al-4V alloy and 316STS). The thickness of the cancellous bone between the femoral stem and the cortical bone affected the stress concentration on the surface of the cortical bone.

Effects of Interphase Regions of Particulate-Reinforced Metal Matrix Nanocomposites Using a Discrete Dislocation Plasticity Model

AbstractMetal matrix nanocomposites (MMNCs) show significant promise for use as structural and/or functional materials. In recent years, discrete dislocation simulations have been used to perform a numerical analysis on MMNCs. Although the trend of increasing flow stress and degree of hardening with a larger particle volume fraction and decreasing particle size were captured by existing simulations, the effects of these parameters on the mechanical behavior of MMNCs shown in these analyses were not as substantial as those reported in experiments. Meanwhile, the presence of thermally induced dislocations and chemical reactions between the matrix and inclusions suggest that interphase regions should be accounted for in the simulation. By using a level set in the extended FEM (XFEM), interphase regions are introduced into the numerical model. The effects of elastic properties, thickness of the interphase regions, and resistance to dislocation motion within the interphase regions are examined in this study.

Contact analysis in the presence of an ellipsoidal inhomogeneity within a half space

Many materials contain inhomogeneities or inclusions that may greatly affect their mechanical properties. Such inhomogeneities are for example encountered in the case of composite materials or materials containing precipitates. This paper presents an analysis of contact pressure and subsurface stress field for contact problems in the presence of anisotropic elastic inhomogeneities of ellipsoidal shape. Accounting for any orientation and material properties of the inhomogeneities are the major novelties of this work. The semi-analytical method proposed to solve the contact problem is based on Eshelby’s formalism and uses 2D and 3D Fast Fourier Transforms to speed up the computation. The time and memory necessary are greatly reduced in comparison with the classical finite element method. The model can be seen as an enrichment technique where the enrichment fields from the heterogeneous solution are superimposed to the homogeneous problem. The definition of complex geometries made by combination of inclusions can easily be achieved. A parametric analysis on the effect of elastic properties and geometrical features of the inhomogeneity (size, depth and orientation) is proposed. The model allows to obtain the contact pressure distribution – disturbed by the presence of inhomogeneities – as well as subsurface and matrix/inhomogeneity interface stresses. It is shown that the presence of an inclusion below the contact surface affects significantly the contact pressure and subsurfaces stress distributions when located at a depth lower than 0.7 times the contact radius. The anisotropy directions and material data are also key elements that strongly affect the elastic contact solution. In the case of normal contact between a spherical indenter and an elastic half space containing a single inhomogeneity whose center is located straight below the contact center, the normal stress at the inhomogeneity/matrix interface is mostly compressive. Finally when the axes of the ellipsoidal inclusion do not coincide with the contact problem axes, the pressure distribution is not symmetrical.

Effect of elastic properties on the behaviour of beams

The present work illustrates the method of initial functions (MIF) to see the effect of elastic properties on the behaviour of the beam. Generally for beams, modulus of elasticity, shear modulus and Poisson’s ratio are the commonly used parameters, however in the present study, varied Poisson’s ratio has been considered and its effect on the behaviour of beam has been observed. The MIF being an analytical method have the ability to workout exact solutions of different types of problems without the use of hypotheses about the character of stress and strain. In the present study, the equations of two-dimensional elasticity have been used for deriving the governing equations.

Study of the electrical properties of thin SmS films at high pressures

The pressure-induced shift of impurity levels under hydrostatic compression (−1.9 × 10−2 meV/MPa) at T = 300 K has been derived from measurements of the behavior with temperature of the electrical resistance of thin polycrystalline SmS films on glass substrates at different pressures. The difference between the pressure-induced shifts of impurity levels in thin films and single crystals has been attributed to the effect of elastic properties of the substrate material. It has been shown that the semiconductor-metal phase transition in SmS films does not occur at pressures of up to 1000 MPa, because the impurity levels triggering the mechanism of phase transition at such pressures are not in the conduction band.

Effects of elastic properties on the wave propagation in cancellous bones ‐ a simulation study ‐

For diagnosing osteoporosis, ultrasonic systems are considered a powerful tool, because ultrasonic waves strongly depend on the elasticity and structure of cancellous bones. We have reported the separation of longitudinal waves into fast and slow waves, a phenomenon that is strongly connected to the alignment of bone trabeculae.In order to understand this complicated wave propagation, we have simulated the wave propagations with the finite‐difference time‐domain (FDTD) method using three‐dimensional X‐ray CT images of actual cancellous bones. In this simulation, the effects of elastic properties in the solid portions are important. One idea is to adopt the experimentally observed ultrasonic properties of cortical bone. However, we should remind the possible problems like the elasticity difference between cancellous and cortical bones, individual differences, and anisotropy. In this study, then, we have investigated the influences of elastic properties, Poisson's ratio, and densities of solid portion (trabeculae). As a result, we confirmed that the small changes give strong influences on not only the wave speed but also the amplitudes of fast and slow waves. The influence on the amplitudes seems to come from the changes of acoustic impedance of trabeculae. The results show the importance of elastic properties in the simulation.

Cartilage Tissue Engineering using a Elastic Poly (L-Lactide-co-ε-Caprolactone) Scaffold

Mechano-active scaffolds were fabricated from very elastic poly(L-lactide-co-ε-carprolactone). The scaffolds with 80 % porosity and 300~500 μm pore size were prepared by a gel-pressing method. As a control group for elastic properties of polymer scaffolds, rigid poly L-lactide scaffolds were fabricated. The scaffolds were seeded with chondrocytes and cultured to evaluate the effect of elastic properties of polymer scaffolds for the differentiation and the ECM secretion of chondrocytes. Also, the chondrocytes-seeded constructs were implanted in nude mice subcutaneously to investigate their biocompatibility and cartilage formation. From the biochemical analyses, chondrogenic differentiation was sustained and enhanced significantly and chondral extracellular matrix was increased through mechanical stimulation of dynamic environment in the dynamic body systems. Histological analysis showed that implants of PLCL constructs formed mature and well-developed cartilaginous tissue, as evidenced by chondrocytes within lacunae. Consequently, the elastic PLCL scaffolds could be used to engineer cartilage in mechanically dynamic environments

Development of methods for designing structural elements made of structurally heterogeneous materials by developing physicomechanical models

Methods for designing structural elements made of structurally heterogeneous materials by developing vectorial models and studying the scale effect of elastic properties have been developed. Results of calculation of stress-strain states with allowance for structural and geometric factors of stress and strain concentration are presented.

Effect of elastic property of material on stress in solar panel under alternative temperature

The effect of material's elastic property on the maximal stress in solar panel (SP) under alternative temperature was investigated using an analytical method. Results showed that the maximal tensile/press and the shear stress existed in polyimide and the silicone rubber between composite materials and polyimide film. Employing polyimide with lower elastic modulus or silicone rubber with lower shear modulus would decrease the structural stress and obtain structure optimization.

2-D Mesoscopic Simulation of Two-Phase Materials Containing Short Fibers.

The two-dimensional mesoscopic simulation method previously proposed by one of the authors for brittle microcracking solids is applied to the analysis of two-phase materials containing short fibers. Numerical results are presented to demonstrate validity of the proposed method. The effect of elastic property, slenderness, volume fraction, fiber-end cracks and orientation-distribution function of short fibers on overall elastic properties of two-phase materials has been studied. The microcracking behavior under tensile, shear and bending stress conditions accompanied by crack deflection, crack bridging and fiber pull-out has also been analyzed by the proposed mesoscopic simulation method.

Reproducibility of Stone Casts Obtained from Alginate Impression Materials : Effects of Elastic Properties

Reproducibility of Stone Casts Obtained from Alginate Impression Materials : Effects of Elastic Properties

The Cracking and Decohesion of Thin Films

ABSTRACTThe cracking and decohesion of thin films can be characterized by critical values of a non-dimensional parameter governed by the residual stress, the film thickness and a fracture resistance. This article describes the status of understanding concerning the magnitude of this number for various types of adherent film on either brittle or ductile substrates. Important effects of elastic properties, substrate thickness and yield strength are described.