Showing papers on "Material properties published in 1973"

Effect of Particle Shape on the Engineering Properties of Granular Soils

Abstract: THE USE OF RELATIVE DENSITY CORRELATIONS BASED ON AN "AVERAGE" SAND TO PREDICT SOIL BEHAVIOR WITHOUT CONSIDERING THE PARTICLE SHAPE CAN RESULT IN POOR OR MISLEADING PREDICTIONSEXPERIMENTAL DATA SHOW THAT THE PARTICLE SHAPE HAS A PRONOUNCED EFFECT ON ALL ENGINEERING PROPERTIES STUDIEDANGULARITY OF THE PARTICLES INCREASES THE MAXIMUM VOID RATIO, STRENGTH, AND DEFORMABILITY OF COHESIONLESS SOILSVARIATIONS IN ENGINEERING PROPERTIES DUE TO PARTICLE SHAPE CAN BE AS LARGE AS VARIATIONS ASSOCIATED WITH LARGE DIFFERENCES IN RELATIVE DENSITYPENETRATION TESTS IN SMALL CONTAINERS WITH SMALL RODS SUGGEST THAT THE STANDARD PENETRATION TEST IS INFLUENCED BY BOTH THE ANGULARITY AND DENSITY OF COHESIONLESS SOILS /AUTHOR/ ABSTRACT OF THE SYMPOSIUM IS IRRD ABSTRACT NO 210328

Theory of the Thermodynamic Properties of Liquid Metals

Abstract: Thermodynamic properties of the liquid metals Li, Na, K, and Al are calculated using a pseudopotential model together with an application of thermodynamic perturbation theory based on the Gibbs-Bogoliubov inequality. The theory is used to predict many properties associated with the melting phenomenon; for example, the melting temperature and density as a function of temperature, and the latent heat of fusion. It is found that the theory reproduces the trend in latent heats between the alkali metals, in contrast to previous work, although quantitative agreement with experiment is no better than has been obtained before. The theory is also applied to the prediction of thermodynamic properties on and away from the melting curve; in particular, the specific heat and velocity of sound of sodium are calculated over a wide range of temperature. Agreement with experiment is found to be good.

Complex thermodynamic systems

Abstract: 1 Introduction.- 1.1. The Equations of the First and Second Laws of Thermodynamics.- 1.2. Work.- 1.3. Heat Capacities.- 1.4. The Differential Equations of Thermodynamics.- 2 Equilibrium Thermodynamic Systems Which Undergo Other Forms of Work in Addition to Work of Expansion.- 2.1. Criteria for Equilibrium in Thermodynamic Systems.- 2.2. The Chemical Potential.- 2.3. Equilibrium Conditions in an Isolated Homogeneous System.- 2.4. The Conditions for Phase Equilibrium.- 2.5. The Maxwell Equations.- 3 Magnets.- 3.1. Introduction.- 3.2. Basic Thermodynamic Relations for Magnets.- 3.3. The Heat Capacities of a Magnet.- 3.4. Thermodynamic Processes in Magnets.- 3.5. The Magnetocaloric, Magnetostrictive, and Magnetoelastic Effects.- 3.6. Adiabatic Demagnetization.- 4 Insulators.- 4.1. Introduction.- 4.2. The Basic Thermodynamic Relations for Insulators.- 4.3. The Heat Capacities of an Insulator.- 4.4. Thermodynamic Processes in Insulators.- 4.5. The Piezoelectric, Electrostriction, Electrocaloric, and Pyroelectric Effects.- 5 Superconductivity.- 5.1. Introduction.- 5.2. Thermodynamics of the Transition from the Superconducting State to the Normal State.- 5.3. The Phase Diagram of a Superconductor.- 5.4. The Heat Capacity in the Superconducting and Normal Phases - Rutgers Formula.- 5.5. Magnetostriction of a Superconductor.- 6 Surface Phenomena.- 6.1. Some Basic Properties of Surfaces Separating Phases.- 6.2. Surface Tension.- 6.3. Basic Thermodynamic Relations for Surfaces.- 6.4. The Effect of Surface Phenomena on the Thermodynamic Properties of a System.- 6.5. Phase Equilibrium Conditions Taking Account of the Properties of the Phase Separation Surface.- 6.6. Capillarity.- 7 Gases and Liquids in a Gravitational Field.- 7.1. Basic Thermodynamic Relations for a System in a Gravitational Field.- 7.2. Distribution of Pressure and Other Quantities with Height of a Gas or Liquid Column.- 7.3. Entropy of a System in a Gravitational Field.- 7.4. Adiabatic Flow in a Gravitational Field.- 7.5. Thermodynamics of the Atmosphere.- 8 Liquids in the Weightless State.- 8.1. Features of the Behavior of Two-Phase Systems in the Weightless State.- 8.2. Possibility That One of the Phases May Lose Contact with the Walls of the Vessel.- 8.3. Stable Equilibrium States of a Two-Phase System.- 9 Radiation.- 9.1. Radiation in a Cavity as a Thermodynamic System.- 9.2. The Equations of State for a Photon Gas.- 9.3. Entropy and Chemical Potential of the Photon Gas.- 9.4. Thermodynamic Processes in a Photon Gas Heat Capacity.- 10 Elasticity of Solids.- 10.1. Basic Thermodynamic Relations for Solids.- 10.2. The Equation of State for an Elastically Deformed Rod.- 10.3. The Caloric Properties of an Elastically Deformed Rod.- 10.4. Adiabatic and Isothermal Deformation of a Rod.- Supplementary Readings.

Thermodynamic properties of copper and its inorganic compounds

Abstract: : The principal purpose of this volume on thermodynamic properties of copper and its inorganic compounds is to supply information that can be used by the extractive metallurgist as a basis for improving existing processes or for establishing new ones. However, for the sake of completeness, all relevant data on copper compounds, through June 1971, have been critically reviewed and evaluated. As a result, properties for 159 copper-containing substances have been incorporated into the compilation. Thus, the work can be used as a guide also for other areas of thermochemical research. The compilation is divided into several sections. The first section gives enthalpy of formation, Gibbs energy of formation, and entropy of substances at 298 K. The second section gives tabular values of properties of compounds as a function of temperature. Included are heat capacity, entropy, Gibbs energy function, enthalpy relative to 298 K, enthalpy of formation, Gibbs energy of formation, and equilibrium constant of formation. The third section gives data for selected chemical reactions over ranges of temperature, with emphasis on reactions of metallurgical interest. Tabular values are given for enthalpy of reaction, Gibbs energy of reaction, and equilibrium constant of reaction.

Analytical Investigation of Stress Concentrations Due to Holes in Fiber Reinforced Plastic Laminated Plates, Three-Dimensional Models.

Abstract: : A three-dimensional analysis for the stress distributions around a hole in a laminated plate is presented. The method of stress analysis is based on a complementary energy formulation with three-dimensional equilibrium finite elements. Three Maxwell stress functions are associated with each element. Finite element representations for the stress functions include positive and negative powers of the radial coordinate, r. This representation was found to give better stress solutions than the conventional representations with only positive powers of r. Numerical verification checks of the analysis for two-dimensional problems are presented. Three-dimensional finite element solutions are presented for four-and six- layered plates with symmetric lay-up angles. Material properties representing boron/epoxy laminas are used. Problems are selected to show the influence of laminate stacking sequence on the transverse normal and shear stresses around the hole. Stresses obtained from two-dimensional effective modulus representations are compared with three- dimensional results. (Author-PL)

A Transient Elastic-Plastic Thermal Stress Analysis of Flame Forming

Abstract: The work described here is part of a large experimental and theoretical program directed at obtaining a better understanding of the mechanics of flame bending. A capability for predicting the transient behavior of a line heated plate during heating and cooling is presented. Material properties are temperature dependent. Elastic-plastic stress-strain relations are used. Material unloading from the plastic range is treated. Deformations of a plate are predicted at various times during heating and cooling and compared with experimental results. The analysis is also carried out for consecutive heating and cooling cycles.

A model for unstable shear crack propagation in pipes containing gas pressure

Abstract: A tentative analysis of an unstable shear crack propagating axially in the wall of a long pipe under gas pressure is developed. Six processes known to be associated with crack propagation are treated numerically: (1) axial decomptession of the gas, (2) bulging of the pipe wall, (3) radial decompression of the gas, (4) local stress and strain intensification at the crack tip, (5) plastic deformation, and (6) ductile cracking. The treatment is quasi-static; dynamic effects in the pipe wall are ignored. Because the numerical descriptions included in the model are approximate and incomplete, several variants of the basic model are examined. The response of the model is evaluated for different line pressures, geometries, and material properties and compared with full-scale test data for 100% shear cracks. A wide range of speeds can be calculated for the limits within which the system parameters are specified including the speeds observed in practice. The bulging and decompression characteristics of the model cause the crack speed to be relatively insensitive to line pressure. Yet the calculated crack speeds are influenced by yield strength and toughness of the material. The model does not provide for nonaxial crack paths, nor does it adequately describe crack-arrest possibilities. The paper represents the first step in the analysis of a complex problem.

Mechanical impedance of damped three-layered sandwich rings.

Abstract: Experimental and theoretical results of the radial driving point mechanical impedance of three-layered sandwich rings are presented and discussed. The composite sandwich rings, subjected to a time-harmonic radially-concentrated load, are made up of two thin elastic layers with a thin viscoelastic damping core between them. The effects of the operational temperature and frequency ranges concerned on the viscoelastic material properties are taken into account. Experimental data are compared well with the theoretical predictions over a wide frequency range of interest. Resonant conditions for lobar bending modes are also given.

Buckling of Steel Columns at Elevated Temperatures

Abstract: The buckling loads for pin-ended steel columns subjected to a uniform temperature increase along the length of the member are determined. The column cross sections investigated include: rolled wide flange shapes, welded I-sections, and welded box sections. The effects of residual stress and the influence of temperature on the material properties on the buckling strength in both the elastic and inelastic range are considered. Results are presented in the form of column curves and simple formulas relating the column strength at elevated temperature to that at room temperature. Comparisons of the results obtained in the study with current design provisions are also made.

Thermodynamic properties of liquid gallium-lead alloys

Abstract: Thermodynamic functions for the liquid binary Ga-Pb were calculated from measured activities in the compositional range 10–90 at.% Pb. Enthalpies and excess entropies of mixing were found to be positive over this range at the selected temperature of 1000 K. Combining the free energies calculated in this study with the recently reported heats of mixing, a more reliable set of entropy functions for the Ga-Pb system has resulted. These results are discussed in the light of available information on other alloys of lead with Group IIIA metals.

Finite Element for Reinforced Concrete Frame Study

Abstract: A finite beam-column element which can be used to model the behavior of reinforced concrete members near failure is developed. The derivation of the material properties and a stiffness matrix for the element are presented. Inelastic material properties are characterized by the rigidity of a cross section whose steel could strain harden, and be unsymmetrically placed. The element stiffness matrix includes nonlinear softening due to initial forces and nonlinear changes in geometry due to rotation of the element. Inclusion of each of these parameters is necessary in order for the element to be used to adequately study the inelastic interaction of entire frames near limit loads.

Reactions in the gas and liquid phases: Comparison of kinetic and thermodynamic data

Abstract: An analysis is made of relationships to be expected between the enthalpies and entropies of reactions carried out in the gas and liquid phases, assuming ideal thermodynamic behavior of the components. The results of the analysis are compared with experimental results reported in the literature. Some discrepancies are noted. These may be the consequence of experimental error or may be due to substantial deviations from thermodynamic ideality. If the latter is commonplace, there will be difficulties in making useful predictions and correlations of thermodynamic and kinetic parameters in the liquid phase.

Pure bending of helical wound composite cylinders

Abstract: In order to simulate the influence of specimen misalignment, we determine the elastic response of a helical wound composite tube under pure bending using an existing general solution for a wide class of boundary value problems. Theoretical results for several composite materials of engineering interest are presented which illustrate the influence of material properties on the stress field.

Metallurgical Effects of High Energy Rate Forming

Abstract: The authors of preceding tutorial papers in this volume have discussed the physical nature of shock-wave propagation in solids, the experimental techniques involved, and some aspects of transient mechanical behavior. The purpose of the present paper is to consider, firstly, the application of stress and shock waves to the technology of material fabrication and processing, and secondly, to assess the ensuing effects on material properties.

Forced Response of a Discontinuously Constrained Damped Ring

Abstract: Experimental and theoretical results are presented and discussed for the radial driving‐point mechanical impedance of a damped composite ring made of a thin‐walled ring having a finite number of mass segments equally spaced and attached to its circumference by a viscoelastic material. The theoretical analysis considers the kinetic and potential energies of a thin‐walled ring; the kinetic energies of tangential, rotational, and radial motions of each of the mass segments; and the energy of the viscoelastic material due to the relative motion of the ring and mass segments. The effects of the operational temperature and frequency ranges of concern on the viscoelastic material properties are taken into account in the analysis and calculations. Radial point impedance tests were conducted on two steel rings (4.06 and 5.125 in.) having 12 and 16 mass segments attached with an acrylic base viscoelastic material and a coal‐tar base epoxy, respectively. Experimental data show good comparison with theoretical result...

Thermodynamic and physical properties of solids in electric fields

Abstract: A new rotationally invariant electric displacement variable is defined as the thermodynamic conjugate of the rotationally invariant electric field variable. Piezoelectric and pyroelectric properties defined in terms of these thermodynamic variables have the full symmetry conferred by Maxwell relations. However, analogous properties defined in terms of the usual physical electrical variables in general differ from the thermodynamic properties, and do not obey Maxwell relations. The differences depend on the electrical conditions, but are nonzero in pyroelectric crystals even at zero electric field, because of the spontaneous polarization. This situation resembles that found for thermoelastic properties, which differ according to whether they are defined in terms of the physical Cauchy stress or the thermodynamic stresses (tensions). In each case analogous quantities coincide only at constant strain and rotation.

Analytical Determination of Pressure on Formwork

Abstract: A method is presented for determining the distribution of form pressure during the pouring of a vertical slab from a chemically hardening material such as concrete. The pressure distribution against the form surfaces results from the interaction of gravity with the progressive hardening and shrinkage of the material. Essential aspects of the formulation include time-dependent constitutive equations for the solidifying material which incorporate the effects of shrinkage, and a transformation to a moving coordinate system which handles the motion of the pouring surface. Hardening occurs as the consequence of the conversion of the material from an initial liquid-like condition into an elastic solid, where intermediate states during hardening are represented by a mixture of two components having the initial and final properties of the solidifying material. Graphical comparisons of results obtained from the analytical formulation are shown and examined in relation to experimental data and recommended design practice.

Thermodynamic Properties of Liquids, Including Solutions. X. Prediction of Polymer Solution Properties

Abstract: A comprehensive theory of the thermodynamic properties of solutions must deal with the dependence of the Gibbs free energy, the enthalpy, and the entropy on concentration, temperature, and the chemical compositions of the components. The author’s new theoretical approach, which appears to satisfy the requirements considerably better than previous approaches, is used as a basis of a discussion of the prediction of the thermodynamic properties of solutions from parameters previously determined for other solutions, with a minimum of new data. Procedures for making predictions expected to be relatively accurate and (using a smaller amount of new experimental data) for making approximate predictions are both dealt with.

Thermodynamic properties and phase diagrams of the Fe-Co and Ni-Pt systems

Abstract: Heat capacities for Fe-Co and Ni-Pt alloys of various compositions have been measured between 300 and 1130. The enthalpies of the order–disorder transformation occurring in these alloys were determined from these measurements. These enthalpy of transformation values were combined with extant thermodynamic data for the disordered phase to calculate thermodynamic properties for the ordered phase, which were then used to derive more information on the equilibrium diagrams for the Fe-Co and Ni-Pt systems.

Thermoelastic analysis of solar cell arrays and their material properties

Abstract: A thermoelastic stress analysis procedure is reported for predicting the thermally induced stresses and failures in silicon solar cell arrays. A prerequisite for the analysis is the characterization of the temperature-dependent thermal and mechanical properties of the solar cell materials. Extensive material property testing was carried out in the temperature range -200 to +200 C for the filter glass, P- and N-type silicon, interconnector metals, solder, and several candidate silicone rubber adhesives. The analysis procedure is applied to several solar cell array design configurations. Results of the analysis indicate the optimum design configuration, with respect to compatible materials, effect of the solder coating, and effect of the interconnector geometry. Good agreement was found between results of the analysis and the test program.