Showing papers on "Young's modulus published in 1971"

Single crystal elastic constants and calculated aggregate properties

Abstract: : Data on the elastic properties of single crystals have been collected from the literature published through mid-1964. The elastic properties of isotropic aggregates (Young's modulus, Poisson's ratio, shear modulus, bulk modulus, compressibility, velocity of shear waves, and the velocity of compressional waves) are calculated according to the schemes of Voigt and Reuss. The tables include about 1100 determinations. (Author)

The elastic constants of the human lens

Abstract: 1. When the lens is spun around its antero-posterior polar axis in an apparatus designed for the purpose, high speed photography can be used to record its changing profile. By this method a variable radial centrifugal force can be applied to the lens which mimics the pull of the zonule.2. If the lens is not stressed at its centre beyond 100 Nm(-2) it behaves as a truly elastic body. When stressed beyond this limit visco-elastic strain is produced at its poles.3. The human lens has isotropic elastic properties at the extremes of life, but at the other times Young's Modulus of Elasticity varies with the direction in which it is measured.4. Young's Modulus of Elasticity of the lens varies with age, polar elasticity and equatorial elasticity, at birth being 0.75 x 10(3) and 0.85 x 10(3) Nm(-2) respectively, while at 63 years of age both are equal to 3 x 10(3) Nm(-2).5. A comparison of Young's Modulus of the young human lens with that of the rabbit and cat shows that the polar elasticity of the lenses of these animals was 5 times greater in the young rabbit, and 21 times greater in the adult cat. Equatorial elasticities of the rabbit and human lens were equal, while in the cat the equatorial elasticity was four times greater.6. A mathematical model showing the lens substance possessing a nucleus of lower isotropic elasticity than that of the isotropic elastic cortex surrounding it, accounts for the difference between polar and equatorial elasticity of the intact adult lens.7. The implications of these findings are discussed in relation to:(i) accommodation and the rheological properties of the lens;(ii) possible differences in the physical state of the lenticular proteins in the cortex and nucleus which may account for the senile variations in Young's Modulus of Elasticity in these regions of the lens;(iii) the loss of accommodation due solely to an increase in Young's Modulus of Elasticity of the lens between the ages of 15 and 60. This would amount to 44% of the total observed in vivo.

Analysis of thermal elastic-plastic stress and strain during welding by finite element method

Abstract: It is well known that welding thermal stresses and resulting residual stresses influence the strength of welded construction, causing troubles such as brittle fracture, buckling and weld cracking. At the instant of welding, a limited portion of the welded joint is heated up to a very high temperature and cooled down to room temperature. In the thermal cycle which takes place, the temperature distribution changes with time and it affects the mechanical properties of the metals. In order to perform a reliable theoretical analysis, the above mentioned factors should be taken into account. The authors developed a method of theoretical analysis of this problem based on the finite element method, with consideration of the effects of changes in the modulus of elasticity, yield stress and the coefficient of linear thermal expansion of the metal with temperature. They analysed thermal transient stresses induced in a butt weld under a moving electrode and also in a fillet weld in the courses of the first and second beads and obtained various information on thermal stress history in the process of welding. Examples verifying usefulness of the method are cited.

The anisotropy of Young's modulus, shear modulus and Poisson's ratio in cubic materials

Abstract: The directional behaviour of Young's modulus, shear modulus, and Poisson's ratio are expressed for a number of crystallographic planes for cubic materials. Their behaviour as a function of direction on a particular plane is shown to be a simple sum of sines and cosines of twice and sometimes of four times the angle. A general expression gives the coefficients for the sines and cosines and a table gives the coefficients for 19 planes on the standard triangle of the stereographic projection. Superposed on the stereographic projection are shown polar plots of the shear modulus Gprime12 (1prime direction normal to the plane) for silicon. Examples are also given showing G12prime for copper for some planes of zones [1bar above 00], [1bar above 10] and [2bar above 10].

The dependence of the bulk modulus, Young's modulus, creep, shrinkage and thermal expansion of concrete upon aggregate volume concentration

Abstract: A simple theoretical approach is used to obtain expressions for the dependence of a number of physical properties of concrete upon the physical properties of its constituents and the aggregate volume concentration. It is assumed that concrete approximates to a two phase material consisting of aggregate particles dispersed in a cement matrix and it is shown that the theory is in reasonable agreement with some Young's modulus, creep and shrinkage measurements made on concrete.

The prediction of the tensile properties of flexible foams

Abstract: An idealized model for flexible foam in tension is developed. The model includes large deformations and cell structure orientation before and after deformation. It is predicted that two quantities affect the initial modulus of an unoriented foam: the density and a cell structure parameter. Data for latex foam show that the model correctly predicts the initial tensile modulus. The model also predicts that cell structure orientation is a reasonable method for achieving a desired modulus without altering the density.

Elastic moduli of pressure-sintered nickel oxide

Abstract: The elastic moduli of pressure-sintered nickel oxide near theoretical density have been measured by three different techniques. The values of Young's modulus and the shear modulus at room temperature determined by the resonant sphere method were 9.58×1011 dynes/cm2 and 3.38×1011 dynes/cm2, respectively. The value of Young's modulus determined by a three-part composite oscillator technique was 9.56×1011 dynes/cm2, in good agreement with the resonant sphere measurements. Measurements of Young's modulus and shear modulus by the pulse-transmission method were subject to fairly large end effects, which gave lower values. The temperature of the anomalous increase in Young's modulus and in relative acoustic loss was found to be 250°C±1/2°C, in excellent agreement with previously reported measurements for the Neel temperature of nickel oxide.

The elastic constants of a two-phase composite material

Abstract: A new formula for the shear modulus of a macroscopically homogeneous and isotropic composite material is derived Geometries for which this formula is applicable are suggested and correspond to those which may be obtained in two-component composites consisting of two continuous phases

Numerical calculation of storage and loss modulus from stress relaxation data for linear viscoelastic materials

Abstract: Numerical formulae are given for calculation of storage and loss modulus from the known course of the stress relaxation modulus for linear viscoelastic materials. These formulae involve values of the relaxation modulus at times which are equally spaced on a logarithmic time scale. The ratio between succeeding times corresponds to a factor of two. Bounds for the relative error of those formulae were derived. These bounds depend on the value of the damping, tanδ, at the angular frequency,ω. The lower the damping values, the easier is the calculation of the storage modulus. This calculation involves the value of the relaxation modulus at timet 0=1/ω, and that of its derivative with respect to the logarithm of time in a rather narrow region aroundt 0. By contrast, the calculation of the loss modulus is difficult. This calculation involves the value of the derivative of the relaxation modulus with respect to the logarithm of time in a broad interval aroundt 0. Especially the behaviour of the relaxation modulus at timest

Initial Settlement of Structures on Clay

Abstract: A METHOD FOR HAND CALCULATION FOR PREDICITNG THE SETTLEMENT (DUE TO UNDRAINED SHEAR) OF STRUCTURES ON STRUCTURES ON SATURATED CLAY WHEN LOCAL YIELDING OCCURS IN THE FOUNDATION SOIL IS PROPOSED. THE METHOD EMPLOYS A CORRECTION TO THE SETTLEMENT COMPUTED FROM ELASTIC THEORY I. E., WITHOUT ANY YIELDING USING DIMENSIONLESS PLOTS DEVELOPED FROM FINITE ELEMENT ANALYSES FOR THE LOADING OF A HOMOGENOUS, ELASTO- PLASTIC SOIL. THE METHOD REQUIRES A KNOWLEDGE OF THREE PARAMETERS: THE ELASTIC VALUE OF YOUNG'S MODULUS IN UNDRAINED SHEAR; THE ULTIMATE BEARING CAPACITY; AND THE INITIAL SHEAR STRESS RATIO. YIELDING WILL NOT SIGNIFICANTLY INCREASE THE INITIAL SETTLEMENT UNLESS THE INITIAL SHEAR STRESS RATIO IS GREATER THAN 0.4, WHICH CORRESPONDS TO A FOUNDATIONS SOIL WITH AN OVERCONSOLIDATION RATIO OF 1.5 OR LESS. THE PROPOSED METHOD FOR COMPUTING INITIAL SETTLEMENT WOULD APPLY MODULUS IN UNDRAINED SHEAR AND INITIAL SHEAR STRESS RATIO RARELY USED. SINCE EVALUATION OF YOUNG'S MODULUS IN UNDRAINED SHEAR AND INITIAL SHEAR STRESS SRATIO CAN BE EXPENSIVE AND TIME-CONSUMING, TYPICAL VALUES ARE PRESENTED WHICH COULD BE SELECTED ONCE THE PLASTICITY CHARACTERISTICS, UNDRAINED SHEAR STRENGTH AND STRESS HISTORY OF THE FOUNDATION CLAY WERE ESTABLISHED. AN ALTERNATE METHOD FOR DETERMINING INITIAL SETTLEMENT WHICH UTILIZES SOIL PROPERTIES DETERMINED FROM IN-SITU PRESSURE-METER TESTS, IS COMMENTED ON.

Dynamic Tensile Strength of Concrete Materials

Abstract: THE DYNAMIC TENSILE STRENGTH OF PLAIN CONCRETE, FIBER REINFORCED CONCRETE, AND A POLYESTER CONCRETE IS EVALUATED IN TERMS OF THE CRITICAL FRACTURE STRAIN ENERGY. BASED ON THE FRACTURE STRAIN ENERGY REMAINING CONSTANT, IT WAS SHOWN THAT THE FRACTURE STRAIN SHOULD VARY AS THE ONE-THIRD POWER OF STRAINING RATE OR THE INVERSE ONE-HALF POWER OF RISE TIME. THIS WSA EXAMINED ON PRISMATIC SPECIMENS OF THREE TYPES OF CONCRETE AND FOUND TO AGREE WITH EXPERIMENTAL RESULTS. THE TESTS WERE ACCOMPLISHED USING AN IMPACT LOADER AND A STRAIN GAGE SYSTEM. THE PAPER ALSO POINTS OUT THE RELATIONSHIP OF THIS TYPE OF TEST TO THE GENERAL PROBLEM OF SPALLATION OF CONCRETE BY DYNAMIC TENSILE PULSES. /ACIJP/

Unidirectional, high modulus knitted fabrics

Abstract: Unidirectional reinforcing fabric for resin laminates and the laminates including it, in which parallel yarns of fibers of very high modulus of elasticity, in excess of 8 million pounds per square inch, such as high modulus graphite yarn, with or without some glass fiber yarn, are maintained parallel and uncrimped by knitting them together using a fine, flexible knitting yarn. None of the knitting stitches penetrate any of the high modulus yarns. The wales are very widely spaced relative to high modulus yarn cross-section, in excess of two and one-half times with the coarsest material. The stitches are chain stitches, and the very brittle high modulus graphite is not bent or crimped and is maintained parallel by the chain stitches of fine, flexible knitting yarn.

Production of graphite fibers

Abstract: Graphite fibers having superior strength and modulus of elasticity can be obtained by twisting carbon fibers at a specified twisting rate, and then graphitizing the twisted yarn.

Determination of Poisson's ratio and Young's modulus of low-density polyethylene

Abstract: The extensional moduli and Poisson's ratios of cold-drawn low-density polyethylene sheets have been determined by direct observation of the changes in dimensions under load of electron microscope grids printed on the surfaces of the sheets. The highly drawn sheets show incompressible behavior only for vanishingly small strains. It is proposed that the departure from incompressibility is associated with the departure from linear deformation. It is suggested that the anisotropic behavior can be analyzed in terms of three deformation mechanisms: (a) the c-shear mechanism; (b) incompressible elastic deformation associated with the amorphous regions; and (c) a slip mechanism which produces the departure from linear deformation.

Buckling of Circular Cylindrical Shells with Different Moduli in Tension and Compression

Abstract: An exact solution is derived for buckling of circular cylindrical shells with different elastic moduli in tension and compression under arbitrary combinations of axial and lateral pressure. The combinations include those in which one component of pressure causes tension. Classical buckling theory, by which is implied a membrane prebuckled shape, is used for simply supported edge boundary conditions. General results in a form analogous to Batdorf's classical k-Z form are presented for several ratios of tensile to compressive elastic moduli. Differences in tensile and compressive moduli are observed to cause significant differences in the buckling loads. This situation is particularly acute when only a small tensile loading component exists in conjunction with an apparently dominant compressive loading component. For example, if a small axial tensile loading is present in a principally external pressure loading environment, a reduction of 17% in the external pressure buckling load from the zero axial load case can occur for a tensile modulus that is half the compressive modulus. The present results are important because current composite materials often have significantly different elastic moduli in tension and compression.

Micromechanics Analysis of Porous and Filled Ceramic Composites

Abstract: A finite element analysis was used to calculate the internal stresses and deformations everywhere within spherically filled or porous ceramic materials. This analysis accounts for interactions between inclusions and demonstrates the importance of these interactions on stress fields around the inclusions. Modulus of elasticity and Poisson's ratio were calculated for porous and filled ceramics. The predicted modulus is compared with experimental data for two glass composites; the agreement is excellent.

Flexural properties of equine metacarpus.

Abstract: The flexural tests on 37 whole equine metacarpus bones are described and the results are given in terms of fundamental material properties as a function of age. The moduli of elasticity, rupture, and failure increase then decrease with increasing age. The rupture and failure deformations decrease with age. The stiffness and fragility indices increase with age. Averaging the data for all ages, the modulus of rupture was 35 ksi, the deflection at rupture was 0.22 inches, and the modulus of elasticity was 1.7 × 10 psi. The flexural rupture strength is about twice the uniaxial compression strength and about five times greater than the torsional strength for whole bone tests. The moduli of elasticity are about the same for flexure and uniaxial compression, and about five times greater than the torsional modulus of rigidity for whole equine bone.

Evaluation and prediction of the tensile properties of asphalt-treated materials

Abstract: THE INCREASED USE OF ASPHALT-STABILIZED SUBBASES IN RIGID PAVEMENT STRUCTURES HAS CREATED THE NEED FOR A RATIONAL PROCEDURE BY WHICH TO DESIGN THESE SUBBASES A DESIGN PROCEDURE BASED ON LAYERED THEORY IS PRESENTLY UNDER DEVELOPMENT AT THE UNIVERSITY OF TEXAS AT AUSTIN TO SATISFY THIS NEED THIS THEORETICAL DESIGN METHOD REQUIRES THAT MATERIAL CHARACTERIZATION CONSTANTS SUCH AS MODULUS OF ELASTICITY, POISSON'S RATIO, AND FAILURE STRAINS BE ESTIMATED FOR A VARIETY OF ASPHALT-STABILIZED MATERIALS THIS PAPER DESCRIBES A STUDY THAT WAS UNDERTAKEN TO EVALUATE THE EFFECTS OF 7 DIFFERENT FACTORS ON THE TENSILE PROPERTIES OF ASPHALT-TREATED MATERIALS THE 7 FACTORS INVESTIGATED INCLUDE AGGREGATE TYPE, AGGREGATE GRADATION, ASPHALT VISCOSITY, ASPHALT CONTENT, MIXING TEMPERATURE, COMPACTION TEMPERATURE, AND CURING TEMPERATURE THE TEST RESPONSES DISCUSSED ARE MODULUS OF ELASTICITY, TENSILE STRENGTH, AND TOTAL TENSILE STRAIN THE RESULTS REPORTED WERE OBTAINED FROM A CAREFULLY CONTROLLED INDIRECT TENSILE TEST THE DATA INDICATE THAT THERE IS NO TREND OR CORRELATION BETWEEN EITHER MODULUS OF ELASTICITY AND DENSITY OR TENSILE STRENGTH AND DENSITY HENCE, CHANGES IN DENSITY ALONE CANNOT BE USED AS A MEASURE OF CHANGES IN TENSILE PROPERTIES OF ASPHALT-TREATED MATERIALS BUT MUST BE ACCOMPANIED BY CAREFUL CONSIDERATION OF THE FACTORS INVOLVED IN THE MIX DESIGN BECAUSE OF THE DOMINANT EFFECT OF COMPACTION TEMPERATURE ON THE 3 TENSILE PROPERTIES, IT IS RECOMMENDED THAT PRESENT LABORATORY TEST PROCEDURES BE EXTENDED TO INCLUDE THE EVALUATION OF THE EFFECT OF CHANGES IN COMPACTION TEMPERATURE AND THAT CLOSER CONTROL OF COMPACTION TEMPERATURE IN THE FIELD BE ESTABLISHED THROUGH SPECIFICATION REQUIREMENTS /AUTHOR/

Stiffness of Non-Aligned Fiber Reinforced Composites

Abstract: : A general procedure for predicting the average Young's modulus of short fiber composites is formulated and applied to random mat, three- dimensional random prepreg, and transfer moldings. In all cases a uniform strain analysis agrees closely with experimental data for epoxy composites reinforced with graphite, stainless steel, and glass fibers. This reflects a high average stiffness in the composites. Several limiting cases and specific prediction techniques appearing in the literature are compared for the random composites. Simple formulas are adequate for predicting the Young's modulus of these systems. The effects of component properties on the random modulus are described. A new technique is developed for calculating the average modulus of a general axisymmetric composite by integrating over the orientation distribution.

Use of magnetically variable young's modulus of elasticity and method for control of frequency of electromechanical oscillator

Abstract: Through the practice of this invention there is achieved control of the vibrational frequency of an electromechanical oscillator. This is achieved by utilizing the change in Young''s modulus of elasticity which occurs for certain materials with applied magnetic field, known as the Delta E-effect. By selective annealing in the presence of specially directed magnetic field, the Delta E-effect is selectively altered along specific directions in the vibrational member. Additionally, by control of the Delta E-effect of a sonic delay line, there is achieved control of the delay time for an acoustic pulse propagating therein.

Top reinforcement for pneumatic tires

Abstract: Between the tread of the tire and the body of the tire, whether of the bias filament or radial filament carcass, or having no filamentary carcass, there is embedded a reinforcement band of crossed series of flat parallel elements of metal, plastic, or the like, the angles of intersection of the series being at least 45*, and the elements of each series having a high intrinsic resistance to curvature in the plane of the contact surface. The elements being of a thickness of only a fraction of their width, say a width of the order of a millimeter and a thickness of only a fraction of a millimeter. The interstices and points of intersection of the elements being filled with a rubber composition of relatively low modulus of elasticity. Alternatively, instead of being of metal, plastic, glass fibre, or the like, the bands may be composed of impregnated stranded elements embedded in a rubber having a high modulus of elasticity.

High modulus boron nitride fibers

Abstract: Boric oxide fibers having a maximum diameter of about 10 microns are heated in an ammonia atmosphere under such conditions as to produce partially nitrided fibers consisting essentially of B, N, O and H wherein the N is present to the extent of from about 35 percent to about 55 percent. The partially nitrided fibers are then heated in an inert atmosphere at a temperature of at least about 1800*C while simultaneously subjecting the fibers to sufficient longitudinal tension as to at least prevent longitudinal shrinkage of the fibers and preferably to cause elongation of the fibers during heating. The resulting fibers, consisting essentially of boron nitride, are of high purity and are characterized by a relatively high Young''s modulus of elasticity, which renders them especially suitable for reinforcing plastic, ceramic or metal matrices in the preparation of fiber reinforced composites.