scholarly journals Swelling and Mechanical Properties of Polymer Gels from the Viewpoint of Poisson's Ratio.

1995 ◽  
Vol 68 (7) ◽  
pp. 444-452
Author(s):  
KENJI URAYAMA
Keyword(s):  
Mechanical Properties ◽  
Poisson’S Ratio ◽  
Polymer Gels ◽  
Poisson's Ratio

Measurement of Young's Modulus and Poisson's Ratio of Thin Film by Combination of Bulge Test and Nano-Indentation

2008 ◽  
Vol 33-37 ◽  
pp. 969-974 ◽  
Author(s):  
Bong Bu Jung ◽  
Seong Hyun Ko ◽  
Hun Kee Lee ◽  
Hyun Chul Park
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Young’S Modulus ◽  
Poisson’S Ratio ◽  
Young's Modulus ◽  
Applied Pressure ◽  
Indentation Test ◽  
Poisson's Ratio ◽  
Bulge Test ◽  
Nano Indentation

This paper will discuss two different techniques to measure mechanical properties of thin film, bulge test and nano-indentation test. In the bulge test, uniform pressure applies to one side of thin film. Measurement of the membrane deflection as a function of the applied pressure allows one to determine the mechanical properties such as the elastic modulus and the residual stress. Nano-indentation measurements are accomplished by pushing the indenter tip into a sample and then withdrawing it, recording the force required as a function of position. . In this study, modified King’s model can be used to estimate the mechanical properties of the thin film in order to avoid the effect of substrates. Both techniques can be used to determine Young’s modulus or Poisson’s ratio, but in both cases knowledge of the other variables is needed. However, the mathematical relationship between the modulus and Poisson's ratio is different for the two experimental techniques. Hence, achieving agreement between the techniques means that the modulus and Poisson’s ratio and Young’s modulus of thin films can be determined with no a priori knowledge of either.

Measurement of Cement in Situ Stresses and Mechanical Properties Without Cooling or Depressurization

2021 ◽  
Author(s):  
Meng Meng ◽  
Luke Frash ◽  
James Carey ◽  
Wenfeng Li ◽  
Nathan Welch ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Property ◽  
Elastic Modulus ◽  
Poisson’S Ratio ◽  
Axial Stress ◽  
Triaxial Compression ◽  
In Situ Measurement ◽  
Poisson's Ratio ◽  
Ambient Conditions

Abstract Accurate characterization of oilwell cement mechanical properties is a prerequisite for maintaining long-term wellbore integrity. The drawback of the most widely used technique is unable to measure the mechanical property under in situ curing environment. We developed a high pressure and high temperature vessel that can hydrate cement under downhole conditions and directly measure its elastic modulus and Poisson's ratio at any interested time point without cooling or depressurization. The equipment has been validated by using water and a reasonable bulk modulus of 2.37 GPa was captured. Neat Class G cement was hydrated in this equipment for seven days under axial stress of 40 MPa, and an in situ measurement in the elastic range shows elastic modulus of 37.3 GPa and Poisson's ratio of 0.15. After that, the specimen was taken out from the vessel, and setted up in the triaxial compression platform. Under a similar confining pressure condition, elastic modulus was 23.6 GPa and Possion's ratio was 0.26. We also measured the properties of cement with the same batch of the slurry but cured under ambient conditions. The elastic modulus was 1.63 GPa, and Poisson's ratio was 0.085. Therefore, we found that the curing condition is significant to cement mechanical property, and the traditional cooling or depressurization method could provide mechanical properties that were quite different (50% difference) from the in situ measurement.

Friction and Bearing Loads on Buried Pipes

1973 ◽  
Vol 13 (03) ◽  
pp. 163-174
Author(s):  
Alexander Blake ◽  
Maurice Zaslawsky
Keyword(s):  
Mechanical Properties ◽  
Internal Friction ◽  
Applied Stress ◽  
Phase Difference ◽  
Poisson’S Ratio ◽  
Soil Mechanics ◽  
Poisson's Ratio ◽  
Stress Strain ◽  
Physical Constants ◽  
Design Analyses

Abstract Presented here are results of experimental and theoretical investigations of the behavior of downhole pipe, surrounded by Overton sand or gravel, when subjected to shock from nuclear explosion. The principal effects investigated arelongitudinal friction between the pipe and the stemming material andresistance offered by the stemming material to transverse motion of the pipe. Introduction Stemming materials such as Overton sand and pea gravel are widely used in underground nuclear pea gravel are widely used in underground nuclear testing to ensure containment of the explosion. Present-day theories of mechanics suitable for predicting stresses and displacements within an predicting stresses and displacements within an array of particles of such materials are rather limited because of the stress-strain-time behavior and complicated boundary conditions involved. Thus, measurements representing gross effects only and linearized models of analysis must be relied upon in making the majority of engineering decisions where soil-structure interactions are encountered. Furthermore, because of the number of variables and hardware constraints present in designing deep-hole emplacement systems, the emphasis should be on obtaining experimental data on fullscale or nearly full-scale structural components in association with stemming materials of actual field quality. The experiment discussed in this paper was directed toward the development of basic mechanical properties such as modulus of elasticity, friction characteristics during axial (longitudinal) pipe motion through stemming materials, resistance pipe motion through stemming materials, resistance of stemming materials to transverse pipe displacement, and related physical phenomena that may have further bearing on the usual mechanical properties employed in various design analyses. properties employed in various design analyses. During evaluation of the basic mechanical properties, an attempt was made to develop a properties, an attempt was made to develop a Poisson's ratio type of data for the stemming Poisson's ratio type of data for the stemming materials at hand by using both specialized equipment and standard test equipment normally employed in soil mechanics. The results of the study, however, should be interpreted with due regard to the particulate nature of stemming materials, which do not represent a continuum with well defined stress-strain relationships. To obtain meaningful data on friction and transverse resistance characteristics, a special test rig was designed with particular emphasis on minimizing the scale effects and experimental errors usually encountered. In mechanics the term "friction" is the resistance to motion of two moving objects or surfaces that touch. In this paper we speak of several different types of micron, and therefore some clarification is needed. The friction between sand or gravel and the down-hole pipe as we attempt to move the pipe is one type of friction. A similar type is the friction developed between sand or gravel and the steel block it rubs against in the direct shear test apparatus. Those two examples of friction are rather straightforward, however, the following two present some confusion because they are both referred to as internal friction:Internal friction as used by engineering scientists, physicists, and metallurgists may be defined as the conversion of the mechanical energy of a vibrating solid into heat. This is also referred to as the damping capacity and corresponds to a phase difference between the applied stress and phase difference between the applied stress and its resultant strain.b soil mechanics the concept of internal friction corresponds to friction between the surfaces of individual grains of sand or gravel. In granular materials, both kinds of internal friction occur. In this paper the term "internal friction" is referred to extensively and is used exclusively in the sense of friction between particles. particles. FUNDAMENTALS OF SOIL MECHANICS The mechanical behavior of earth materials such as sand or gravel can be described by suitable physical constants reflecting certain physical constants reflecting certain stress-deformation relations that may then be applied in customary engineering predictions. In dealing with the rigidity of rocks, Young's modulus, E, and Poisson's ratio, are commonly used, and soil Poisson's ratio, are commonly used, and soil mechanics utilizes basic concepts of the theory of elasticity. By analogy to this well established practice, related concepts utilizing elastic practice, related concepts utilizing elastic constants in loading and unloading can be made applicable to stemming materials. SPEJ P. 163

Elasto-Plastic Hemispherical Contact Models for Various Mechanical Properties

2005 ◽  
Author(s):  
John J. Quicksall ◽  
Robert L. Jackson ◽  
Itzhak Green
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Material Properties ◽  
Poisson’S Ratio ◽  
Carbon Steels ◽  
Poisson's Ratio ◽  
Aluminum Bronze ◽  
Contact Models ◽  
Element Technique ◽  
Malleable Cast

This work uses the finite element technique to model the elasto-plastic deformation of a hemisphere contacting a rigid flat for various material properties typical of aluminum, bronze, copper, titanium and malleable cast iron. Additionally, this work conducted parametric FEM tests on a generic material in which the elastic modulus and Poisson’s ratio are varied independently while the yield strength is held constant. A larger spectrum of material properties are covered in this work than in most previous works. The results are compared to two previously formulated elasto-plastic models simulating the deformation of a hemisphere in contact with a rigid flat. Both of the previously formulated models use carbon steel mechanical properties to arrive at empirical formulations implied to pertain to various materials. While both models considered several carbon steels with varying yield strengths, they did not test materials with varying Poisson’s ratio or elastic modulus. The previously generated elasto-plastic models give fairly good predictions when compared to the FEM results for various material properties from the current work, except that one model produces more accurate predictions overall, especially at large deformations where other models neglect important trends due to decreases in “hardness” with increasing deformation.

Biomimetic composites inspired by venous leaf

2017 ◽  
Vol 52 (3) ◽  
pp. 361-372 ◽  
Author(s):  
Gongdai Liu ◽  
R Ghosh ◽  
A Vaziri ◽  
A Hossieni ◽  
D Mousanezhad ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Yield Stress ◽  
Poisson’S Ratio ◽  
Composite Structures ◽  
Volume Fraction ◽  
Matrix Material ◽  
Poisson's Ratio ◽  
Fiber Volume ◽  
Young’S Moduli

A typical plant leaf can be idealized as a composite having three principal fibers: the central mid-fiber corresponding to the mid-rib, straight parallel secondary fibers attached to the mid-fiber representing the secondary veins, and then another set of parallel fibers emanating from the secondary fibers mimicking the tertiary fibers embedded in a matrix material. This paper introduces a biomimetic composite design inspired by the morphology of venous leafs and investigates the effects of venation morphologies on the in-plane mechanical properties of the biomimetic composites using finite element method. The mechanical properties such as Young’s moduli, Poisson’s ratio, and yield stress under uniaxial loading of the resultant composite structures was studied and the effect of different fiber architectures on these properties was investigated. To this end, two broad types of architectures were used both having similar central main fiber but differing in either having only secondary fibers or additional tertiary fibers. The fiber and matrix volume fractions were kept constant and a comparative parametric study was carried out by varying the inclination of the secondary fibers. The results show that the elastic modulus of composite in the direction of main fiber increases linearly with increasing the angle of the secondary fibers. Furthermore, the elastic modulus is enhanced if the secondary fibers are closed, which mimics composites with closed cellular fibers. In contrast, the elastic modulus of composites normal to the main fiber ( x direction) exponentially decreases with the increase of the angle of the secondary fibers and it is little affected by having secondary fibers closed. Similar results were obtained for the yield stress of the composites. The results also indicate that Poisson’s ratio linearly increases with the secondary fiber angle. The results also show that for a constant fiber volume fraction, addition of various tertiary fibers may not significantly enhance the mechanical properties of the composites. The mechanical properties of the composites are mainly dominated by the secondary fibers. Finally, a simple model was proposed to predict these behaviors.

Young's Modulus and Poisson's Ratio Estimation Based on PSO Constriction Factor Method Parameters Evaluation

2019 ◽  
Vol 9 (2) ◽  
pp. 33-46
Author(s):  
George Lucas Dias ◽  
Ricardo Rodrigues Magalhães ◽  
Danton Diego Ferreira ◽  
Bruno Henrique Groenner Barbosa
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Young’S Modulus ◽  
Cantilever Beam ◽  
Poisson’S Ratio ◽  
Inverse Analysis ◽  
Young's Modulus ◽  
Poisson's Ratio ◽  
Factor Method ◽  
Constriction Factor

The knowledge of materials' mechanical properties in design during product development phases is necessary to identify components and assembly problems. These are problems such as mechanical stresses and deformations which normally cause plastic deformation, early fatigue or even fracture. This article is aimed to use particle swarm optimization (PSO) and finite element inverse analysis to determine Young's Modulus and Poisson's ratio from a cantilever beam, manufactured in ASTM A36 steel, subjected to a load of 19.6 N applied to its free end. The cantilever beam was modeled and simulated using a commercial FEA software. Constriction Factor Method (PSO variation) was used and its parameters were analyzed in order to improve errors. PSO results indicated Young's Modulus and Poisson's ratio errors of around 1.9% and 0.4%, respectively, when compared to the original material properties. Improvement in the data convergence and a reduction in the number of PSO iterations was observed. This shows the potentiality of using PSO along with Finite Element Inverse Analysis for mechanical properties evaluation.

FINITE ELEMENT ANALYSIS OF MECHANICAL DEFORMATION OF CHONDROCYTE TO 2D SUBSTRATE AND 3D SCAFFOLD

2015 ◽  
Vol 15 (05) ◽  
pp. 1550077 ◽  
Author(s):  
JINJU CHEN ◽  
D. L. BADER ◽  
D. A. LEE ◽  
M. M. KNIGHT
Keyword(s):  
Mechanical Properties ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Poisson’S Ratio ◽  
Glass Plate ◽  
Mechanical Deformation ◽  
Poisson's Ratio ◽  
3D Scaffold ◽  
Element Analysis ◽  
Cell Functions

The mechanical properties of cells are important in regulation of many aspects of cell functions. The cell may respond differently to a 2D plate and a 3D scaffold. In this study, the finite element analysis (FEA) was adopted to investigate mechanical deformation of chondrocyte on a 2D glass plate and chondrocyte seeded in a 3D scaffold. The elastic properties of the cell differ in these two different compression tests. This is because that the cell sensed different environment (2D plate and 3D construct) which can alter its structure and mechanical properties. It reveals how the apparent Poisson's ratio of a cell changes with the applied strain depends on its mechanical environment (e.g., the elastic moduli and Poisson's ratios of the scaffold and extracellular matrix) which regulates cell mechanics. In addition, the elastic modulus of the nucleus also plays a significant role in the determination of the Poisson's ratio of the cell for the cells seeded scaffold. It also reveals the intrinsic Poisson's ratio of the cell cannot be obtained by extrapolating the measured apparent Poisson's ratio to zero strain, particularly when scaffold's Poisson's ratio is quite different from the cell.

scholarly journals Design and Prediction of a Novel Two-Dimensional Carbon Nanostructure with In-Plane Negative Poisson’s Ratio

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Kun Yuan ◽  
Meng-Yang Li ◽  
Yan-Zhi Liu ◽  
Ren-Zhong Li
Keyword(s):  
Mechanical Properties ◽  
Poisson’S Ratio ◽  
Density Functional ◽  
Mechanical Stability ◽  
Poisson's Ratio ◽  
Negative Poisson’S Ratio ◽  
Two Dimensional ◽  
Carbon Nanostructure ◽  
Ratio Effect ◽  
Negative Poisson's Ratio

The intrinsic negative Poisson’s ratio effect in 2-dimensional nanomaterials have attracted a lot of research interests due to its superior mechanical properties, and new mechanisms have emerged in the nanoscale. In this paper, we designed a novel graphyne-like two-dimensional carbon nanostructure with a “butterfly” shape (GL-2D-1) and its configuration isomer with a “herring-bone” form (GL-2D-2) by means of density functional theoretical calculation and predicted their in-plane negative Poisson’s ratio effect and other mechanical properties. Both GL-2D-1 and GL-2D-2 present a significant negative Poisson’s ratio effect under different specific strains conditions. By contrast, GL-2D-2 presents a much stronger negative Poisson’s ratio effect and mechanical stability than does GL-2D-1. It is hoped that this work could be a useful structural design strategy for the development of the 2D carbon nanostructure with the intrinsic negative Poisson’s ratio.

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