An embeddable straingage unit has been developed for use in this investigation, and the readings from this gage unit proved quite reliable. Taking these principles and applying them to the real earth results in an area of study called geomechanics, which is the focus of the second section. Poissons ratio is an elastic constant defined as the ratio of thelateral contraction to the elongation in the infinitesimal uniaxialextension of a homogeneous isotropic body. Unesco eolss sample chapters environmental and engineering geology vol. In the petroleum engineering industry, geomechanics is used to predict important parameters, such as insitu rock stress, modulus of elasticity, leakoff coefficient and poisson s ratio. Thus, it points out the importance of poisson s ratio in the understanding of some of the questions in rock mechanics. The practical application of rock mechanics is emphasized. Taking these principles and applying them to the real earth results in an area of. Sh min importance of static youngs modulus and poisson s ratio for hydrofracture design static moduli are often used in wellbore stability and insitu stress applications to evaluate the possibility of breakouts, elevated pore pressure, and tectonic stress. The average value of poissons ratio for steels is 0. From the figures it can be seen that with increasing.
Pdf petroleum related rock mechanics enrique garcia. Iii characterization of geologic materials abdul shakoor encyclopedia of life support systems eolss void ratio e. Measuring the static poissons ratio is cumbersome and few values exist in the literature and there is a great temptation to use the abundant dynamic poissons ratio values available. Now, click on poissons ratio under rock mechanics the screenshot below displays the page or activity to enter your values, to get the answer for the poissons ratio according to the respective parameters which are the lateral strain. Advances in negative poissons ratio materials by roderic lakes 1. Rock physics basics need for static moduli 2c 2b s hmin p b 2c 1. Aug 03, 2016 material scientists fascination with negative poissons ratio nanowerk spotlight poissons ratio describes the fundamental elasticity of any solid. The volume of materials that have poissons ratios less than 0. Poisson s ratio poisson s ratio when a force is applied to a body, at right angles to the force, a certain amount of lateral transverse expansion or contraction takes place. In applied rock mechanics, students are provided with basic theory, laboratory demonstrations, handson exercises, and computer modeling demonstrations.
Define poissons ratio in physics mechanical engineering. Youngs modulus and poissons ratio are measured directly in uniaxial compression or extension tests, i. In all fairness it must be stated that in recent years the underlying assumptions for using poissons ratio in rock mechanics have been questioned and the. It means that when a material is loaded within elastic limit than the ratio of lateral strain to the longitudinal strain gives us a constant called poissons ratio. Limits to poissons ratio in isotropic materials general result for arbitrary deformation. It is important as one of the materialfunctions that characterize bulk behavior. More specifically, it examines the role of formation, strength of rock materials, and wellbore mechanics, along with the impact of insitu stress changes on wellbore and. In addition to a comprehensive manual, software is provided for the student to perform wellbore stability calculations. Void ratio is defined as the ratio of the volume of voids to the volume of solids, expressed as a decimal evv vs. Poissons ratio definition and formula of poissons ratio. The stress or stain can be generated by applying the force on the material by the body. The first letter of the subscript refers to direction of applied stress and the second letter to direction of lateral deformation.
More specifically, it examines the role of formation, strength of rock materials, and wellbore mechanics, along with the impact of. Poissons ratio is a measure of the poisson effect, that describes the expansion or contraction of a material in directions perpendicular to the direction of loading. Soil, rock, classification, compaction, consolidation, strength, youngs modulus, poissons ratio, modulus ratio, discontinuities, rock mass classification created date. Poissons ratio of dry rock versus poisson ratio of rock solid at 100 mpa. Poissons ratio is defined as minus the ratio of transverse strain to longitudinal strain in simple tension. Poissons ratio variations in concrete springerlink. Sh min importance of static youngs modulus and poissons ratio for hydrofracture design static moduli are often used in wellbore stability and insitu stress applications to evaluate the possibility of breakouts, elevated pore pressure, and tectonic stress. Introduction poissons ratio is defined as the lateral contraction strain in a solid divided by the longitudinal extension strain mea sured in a simple tension experiment. Since poissons ratio is a mechanical property that plays a role in the deformation of elastic materials, it is utilized in rock engineering problems associated with the deformation of rocks, e. Making and characterizing negative poissons ratio materials. Visit to learn more about the formula and equations of poissons ratio.
With embeddable gage units, and surfacebonded strain gages, concrete test specimens were prepared and tested under uniform. Geomechanical principles for unconventional reservoirs. Limits to poissons ratio in isotropic materials general. Wood handbookchapter 4mechanical properties of wood. If the material is incompressible so e v 0 poissons ratio is n 0. The result is a table giving depthtobottom, vp, and poissons ratio of each layer. The knowledge of the main mechanical constants of a rock mass such as strength, deformability and the poissons ratio is one of the most important for rock engineering design on or in rock mass. Poissons ratio values for rocks article in international journal of rock mechanics and mining sciences 441. Definition of poissons ratio strength of materials.
Pdf estimation of the poissons rate of the intact rock in. Once poissons ratio is known, the elastic modulus can be calculated from the equation. Modern developments relate to seismology, continuum mechanics, discontinuum mechanics, and transport phenomena. Poissons ratio poissons ratio when a force is applied to a body, at right angles to the force, a certain amount of lateral transverse expansion or contraction takes place. Summary of the poissons ratio debate 1990 2003 cseg recorder. Poissons ratio longitudinal strain and lateral strain. The ratio of the transverse to axial strain is called poissons ratio. The calibration rod is made of a material called pmma. The poissons ratios are denoted by lr, rl, lt, tl, rt, and tr. In the petroleum engineering industry, geomechanics is used to predict important parameters, such as insitu rock stress, modulus of elasticity, leakoff coefficient and poissons ratio. Dave boores notes on poissons ratio the relation between p. This video explains the complete definition of poissons ratio with the help of an example, stretching of rubber strip. Drilling operations and well design covers the fundamentals of solid mechanics and petroleum rock mechanics and their application to oil and gasrelated drilling operations and well design.
Poissons name survives in poissons integral, poissons distribution in statistics, poissons constant in electricityand poissons ratio. This paper presents the results of an investigation relating to the variations in the poisson s ratio in compression of concrete. Standard test method for dynamic youngs modulus, shear modulus, and poissons ratio by impulse excitation of vibration1 this standard is issued under the. Increased moisture content increases the static poisson ratio. Different types of rocks may have the same velocity, but have a. The effect of poissons ratio on rock properties onepetro. Thus the ratio between the horizontal and vertical stress referred to as k h v is a function of the poissons ratio.
This chapter provides details of the tests most commonly used to determine fundamental rock mechanics parameters such as, strength index characteristics, compressive and tensile strength, elastic properties youngs modulus and poisson s ratio, rock failure parameters mohrcoulomb cohesive strength and friction angle, ultrasonic behaviour. Poissons ratio of surface soils and shallow sediments. The former is influenced by the constituent mineral composition. First, the subject of it related heavily to the general mechanics of solid materials. It is defined as the ratio of lateral strain to the longitudinal strain within elastic limit. Properties of intact rock in the beginning of rock mechanics in the early 1960s, more attention has been paid to the, p intact rock than to the other features of rock mass. The fluid type in the pores determines poisson s ratio, and in turn, the poisson s ratio of rocks also can be used to infer the pore fluid. The higher poissons ratio of the rock solid is, the higher is poissons ratio of the rock. Determination of poissons ratio for rocks by static and. Poissons ratio the ratio of the transverse contraction of a material to the longitudinal extension strain in the direction of the stretching force is the poissons ration for a material. It also lists the values of poissons ratio of different engineering.
Materials with negative poissons ratio, meaning that they get thinner as they are compressed, do exist. The poissons ratio for the first layer ranged from 8. Pdf estimation of the poissons rate of the intact rock. The fluid type in the pores determines poissons ratio, and in turn, the poissons ratio of rocks also can be used to infer the pore fluid. Bentley abstract poissons ratio is determined by two independent factors, i. Poissons ratio longitudinal strain and lateral strain byjus. Applied rock mechanics training course petroskills arm.
For this it is necessary to know the density of the material. Transverse extensometer installation on a composite specimen to measure poissons ratio model 3575 duration. Roland chemistry division, naval research laboratory, code 6120, washington dc 203755342 april 3, 2012 abstract the lower bound usually cited for poissons ratio. I used the poissons ratio files rather than the individual vs vp and files because i was then assured that the vs vp and values correspond to the same depth range. For small values of these changes, is the amount of transversal expansion divided by the amount of axial compression. Method for the determination of modulus of elasticity and poisson s ratio of rock materials in uniaxial compression. Drilling operations and well design, second edition, keeps petroleum and drilling engineers centrally focused on the basic fundamentals surrounding geomechanics, while also keeping them uptospeed on the latest issues and practical problems. Most materials have poisson s ratio values ranging between 0. In mechanics, poissons ratio is the negative of the ratio of transverse strain to lateral or axial strain. The static poisson ratios of rocks increase with the pressure both under simple and under hydrostatic compression.
For the second layer, the poissons ratio ranged from. Updated with new chapters on operations surrounding shale oil, shale gas, and hydraulic fracturing, and with new sections on in. Pdf determination of poissons ratio of gypsum materials. The value of poissons ratio is the negative of the ratio of transverse strain to axial strain. Interesting, the astm standard contains example values for youngs modulus and poissons ratio for several rock types under unconfined and confined conditions.
It is named after simeon poisson and denoted by the greek letter nu, it is the ratio of the amount of transversal expansion to the amount of axial compression for small values of these changes. Figures 8 and 9 show the created gap among interfaces in thin and thick resin layer. In almost all materials poissons ratio, usually denoted by v, is positive. The poissons ratio, is the ratio of transverse strain, to axial strain, where an axial force has been applied. Thus, it points out the importance of poissons ratio in the understanding of some of the questions in rock mechanics. Standard test method for dynamic youngs modulus, shear. Poissons ratio of dry rock versus poisson ratio of rock solid at 10 mpa. Conventional materials contract laterally when stretched and poissons rati. Aug 06, 2016 problem 1 based on poisson s ratio video lecture from simple stress and strain chapter of strength of materials subject for all engineering students. A material is perfectly incompressible if its poisson s ratio is 0.
Jan 16, 2018 for the love of physics walter lewin may 16, 2011 duration. Poissons ratio problem 1 stress and strain strength of. The harder the rock, the less does the poisson ratio. These four elastic parameters are interrelated such that any one can be expressed in terms of two others and can also be expressed in terms of acousticwave velocity and density table 1.
Values of j toughness of negative poisson s ratio open cell copper foams are enhanced by 80%, %, and 160% for permanent volumetric compression ratio of 2. Aug 03, 2016 material scientists fascination with negative poisson s ratio nanowerk spotlight poisson s ratio describes the fundamental elasticity of any solid. In a viscoelastic materialpoissons ratio is a function of time or frequency that depends on thetime regime chosen to elicit it. Rock mechanics ced 48 designator of legally binding document. How to calculate and solve for poissons ratio rock. Determination of poissons ration and the modulus of. In ither words, is the amoont o transversal expansion dividit bi the amoont o axial compression, for smaw values o thir chynges. Materials that do not deform transversally due to longitudinal strain have a poisson ratio of 0, such as cork. The first introduces important concepts in rock mechanics, including topics such as stress, strain, and rock strength.
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