jap banner
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter UniPHY Group iResearch App Facebook

SECTION LISTING

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

1 Nov 1970

Volume 41, Issue 12, pp. 4755-5042

Page 1 of 3 Pages Next Page | Jump to Page

Generation of High‐Frequency Ultrasonic Waves by Gunn Effect

H. Hayakawa, T. Ishiguro, S. Takada, N. Mikoshiba, and M. Kikuchi

J. Appl. Phys. 41, 4755 (1970); http://dx.doi.org/10.1063/1.1658536 (8 pages) | Cited 3 times

Online Publication Date: 19 November 2003

Full Text: | Download PDF

Show Abstract
The generation of the longitudinal waves in the frequency range up to the microwave region was observed in the GaAs Gunn diode when the applied field exceeded the threshold. This ultrasonic excitation in the Gunn diode is caused by the lattice deformation by the high‐field domains through the piezoelectricity of GaAs. The two possible excitations, in the bulk and at the surface, are discussed using simple models. It is speculated that a properly oriented Gunn diode may be applicable to the narrow beam‐like ultrasonic generator.

Simple Technique for Exciting and Probing Elastic Surface Waves

Robert J. Hallermeier and Orest I. Diachok

J. Appl. Phys. 41, 4763 (1970); http://dx.doi.org/10.1063/1.1658537 (2 pages) | Cited 4 times

Online Publication Date: 19 November 2003

Full Text: | Download PDF

Show Abstract
The liquid‐wedge technique has been used to excite ultrasonic surface waves on various solids; using this technique, only a suitable noncorrosive liquid need come into contact with the solid, and no acoustic power need be coupled into the bulk of the solid. An optical probe was used to measure the surface‐wave pattern excited; data obtained from this probe are presented, and results for the surface‐wave attenuation on stainless steel are given.

Amorphous Carbon Films: Conduction Across Metal∕Carbon∕Metal Sandwiches

M. L. A. MacVicar

J. Appl. Phys. 41, 4765 (1970); http://dx.doi.org/10.1063/1.1658538 (4 pages) | Cited 10 times

Online Publication Date: 19 November 2003

Full Text: | Download PDF

Show Abstract
Very thin films of evaporated carbon have been deposited on various metallic thin film and single‐crystal substrates to form metal∕carbon∕metal sandwiches. Electrical conductivity measurements through the carbon, over a range of temperatures from room temperature to below 1°K, show that conduction is a process of complicated mechanisms dependent on the presence of both structural and impurity defects. At low temperatures, conductivity appears to be independent of temperature, and the carbon films may act as tunneling barriers of effective heights 30–100 meV. These heights can be engineered by suitable choices of evaporation and substrate conditions. Explanation of conduction in these films remains speculative.

Excess Velocity Potential of the Platelet Crystal in a Supercooled Melt

Ernest G. Holzmann

J. Appl. Phys. 41, 4769 (1970); http://dx.doi.org/10.1063/1.1658539 (7 pages) | Cited 6 times

Online Publication Date: 19 November 2003

Full Text: | Download PDF


See Also: Erratum

Show Abstract
Starting with the traditional time‐invariant parabolic‐cylinder model to represent the growth of a platelet‐shaped crystal in a pure supercooled melt, the effect of thermal imbalance at the solid‐liquid interface is calculated. In particular, the heat field equations are solved for the initial excess velocity distribution at the interface, on the assumption that the shape constraint is suddenly replaced by the constraint of heat conservation. The computed results resemble those found for the paraboloidal needle crystal. In particular, the hypothetical parabolic interface tends to bulge with a pronounced peak at one radius behind the leading edge of the platelet crystal. The maximum velocity principle, when applied to this model, yields a square‐law relation between the dimensionless tip velocity and the supercooling for pure ice and water. The results parallel those calculated by Horvay and Cahn for the isothermal model. The curvature effect of surface tension and the effect of the molecular attachment kinetics are found to lower the dimensionless tip velocity by about 20% below that in the isothermal model, uniformly over the range of supercooling considered.

Color Centers and the Thermoluminescence Mechanism in LiF

M. R. Mayhugh

J. Appl. Phys. 41, 4776 (1970); http://dx.doi.org/10.1063/1.1658540 (7 pages) | Cited 67 times

Online Publication Date: 19 November 2003

Full Text: | Download PDF

Show Abstract
Color‐center transformations in pure and dosimetry grade LiF have been studied over the wavelength range 105–750 nm. Both impurity‐ and irradiation‐induced optical absorption were measured, the latter by a relatively high x‐ray exposure at room temperature. Thermal and optical treatments were chosen to induce transformations which are easily related to the thermoluminescence (TL) process. The results demonstrate the following for dosimetry LiF: The TL‐associated 310‐nm absorption results from trapped electrons. The TL process intimately involves V3 centers (113‐nm absorption band). The centers causing the 225‐nm band (Z3 band) and those causing the 137‐nm impurity band may both be involved in the sensitization (and supralinearity) phenomenon. A complete model for the TL is presented and discussed. Not so important to the TL is a broad apparently intrinsic absorption from 120–200 nm which is induced by irradiation in both pure and dosimetry LiF.

Effect of Dislocations on X‐Ray Diffraction Properties of Copper

K. J. Bachmann, T. O. Baldwin, and F. W. Young

J. Appl. Phys. 41, 4783 (1970); http://dx.doi.org/10.1063/1.1658541 (7 pages) | Cited 4 times

Online Publication Date: 19 November 2003

Full Text: | Download PDF

Show Abstract
The effect of dislocations on both integrated intensities and rocking‐curve half‐widths has been studied in an (n, −n) double‐crystal spectrometer arrangement on copper crystals of 103<N<108 dislocations per cm2. The results show that the rocking curve provides a suitable means of characterization of the density and the type of dislocations in this range. The changes in half‐width of the rocking curve and the integrated intensity produced by the dislocations can be described satisfactorily by the model of independently scattering perfect crystal blocks up to a dislocation density of 2×105∕cm2, and at higher dislocation densities, lattice tilts produced by the dislocations appear to be the main source of line broadening.

Electro‐Optic g Coefficients of Pb‐Containing Oxygen‐Octahedra Ferroelectrics: Ceramic (Pb, Ba)(Zr, Ti)O3

Philip D. Thacher

J. Appl. Phys. 41, 4790 (1970); http://dx.doi.org/10.1063/1.1658542 (8 pages) | Cited 32 times

Online Publication Date: 19 November 2003

Full Text: | Download PDF

Show Abstract
Electro‐optic g coefficients, which relate induced birefringence and polarization via the quadratic electro‐optic effect, are found to have the value g11−g12 ≈ g44 ≈ 0.011±0.008 m4∕C2 for 12 oxygen‐octahedra ferroelectrics having Pb in the perovskite A site. Measurements on four such ferroelectrics were made using ceramic compositions of the series (Pb, Ba) (Zr, Ti)O3 which has a diffuse phase transition and a maximum quadratic electro‐optic coefficient of R33−R13=3.4×10−16 m2∕V2 at room temperature. To explain why the measured g is 10 times smaller than those compiled and computed by DiDomenico and Wemple for other oxygen‐octahedra ferroelectrics, the optical‐index dispersion energy ϵd and the birefringence dispersion constant K were determined. Values of ϵd=25 eV and K=−0.5 are as found for the other ferroelectrics. A smaller g must therefore arise from a smaller polarization potential coefficient β, which is defined with respect to energy shifts and polarization of the BO6 perovskite octahedra. Such a definition can lead to a smaller β in Pb‐containing ferroelectrics because the higher polarizability and displacement of the Pb ion contribute polarization which is not properly accounted for. In any case, the g coefficient can no longer be considered as a universal constant for oxygen‐octahedra materials.

Diffusion Models for Hot Pressing with Surface Energy and Pressure Effects as Driving Forces

Robert L. Coble

J. Appl. Phys. 41, 4798 (1970); http://dx.doi.org/10.1063/1.1658543 (10 pages) | Cited 107 times

Online Publication Date: 19 November 2003

Full Text: | Download PDF

Show Abstract
Models for initial‐, intermediate‐, and final‐stage densification under pressure have been developed, which explicitly include both the surface energy and applied pressure as driving forces. For the initial stage, the time dependences and size effects given by the integrated equations are identical to those reported earlier for surface energy (alone) as the driving force. The only modification is that the surface energy (γ) is expanded into (γ+PaR∕π), where Pa is the applied pressure and R is the particle radius. For the intermediate stage of the process, the Nabarro‐Herring and Coble creep models may be adapted to give approximate (∼4×) densification rates for lattice and boundary diffusion models, respectively. In these cases the complex driving force is written as: (Pa∕D+γk), where D is the relative density, and k is the pore surface curvature. At the final stage of the process those models are invalid; an alternate model is developed based on diffusive transport between concentric spherical shells which will give a better assessment of the time dependence of densification high density (>95%); the driving force is (Pa∕D+γk) in this case also. Because of the fact that the pore size is some unknown function of density, the rate equations cannot be integrated without further information. It is shown that of the various relations which have been assumed in development of models for hot pressing, for the effective stress in relationship to the applied stress and the porosity, (Pa∕D) is the only form which satifies the criteria demanded by self‐consistency in generation of steady‐state diffusion models.

Diffusion of Actinides in Pyrocarbons: Thin‐Layer Experiments

R. B. Evans, J. O. Stiegler, and G. M. Watson

J. Appl. Phys. 41, 4808 (1970); http://dx.doi.org/10.1063/1.1658544 (12 pages) | Cited 2 times

Online Publication Date: 19 November 2003

Full Text: | Download PDF

Show Abstract
The diffusion of uranium and thorium in columnar pyrocarbons between temperatures of 1450° and 2065°C has been studied using the usual thin‐layer depletion technique. Constant coefficients are obtained that are in good agreement with results reported elsewhere for uranium diffusion in the 〈a〉 direction at actinide concentrations less than about 0.15‐mg actinide∕cm3. Diffusion coefficients increase at higher actinide concentration. The anisotropic pyrocarbons are well oriented with the basal planes aligned parallel to the deposition surface. Diffusion coefficients parallel to the deposition surfaces are about three orders‐of‐magnitude greater than those in the perpendicular direction. The difference is due primarily to the pre‐exponential term in the usual Arrhenius equation. Autoradiographic studies of specimens in which diffusion occurred perpendicular to the deposition surface show segregation of actinides to growth cone centers or boundaries depending on whether diffusion occurs along or opposite the direction of growth of the pyrocarbon. The segregation is attributed to rapid diffusion parallel to the deposition surface coupled with the roughened nature of the surface. The results are discussed in terms of previously proposed models for actinide diffusion in columnar pyrocarbons.

Approximate Step‐Function Response of a Horizontally Polarized Electromagnetic Wave Reflected at an Imperfectly Conducting Surface

Richard L. Monroe

J. Appl. Phys. 41, 4820 (1970); http://dx.doi.org/10.1063/1.1658545 (3 pages)

Online Publication Date: 19 November 2003

Full Text: | Download PDF

Show Abstract
A two‐term expression consisting of a constant plus the product of an exponential and complementary error function is given for the transient reflected field of a horizontally polarized (E field normal to the plane of incidence) plane wave in free space with a step‐function time variation incident obliquely on a plane imperfectly conducting surface. Curves computed with this expression are shown to be in good agreement with corresponding curves obtained numerically for all values of the time. Asymptotic expressions valid in early and late time are also given.

Method for Determining the Maximum Emission Depth of True Secondary Electrons by Means of Retarding Characteristics

Keisuke Goto and Kazuo Ishikawa

J. Appl. Phys. 41, 4823 (1970); http://dx.doi.org/10.1063/1.1658546 (3 pages) | Cited 1 time

Online Publication Date: 19 November 2003

Full Text: | Download PDF

Show Abstract
A method has been developed to determine the maximum emission depth of true secondary electrons λ. The method is based on observing the retarding potential characteristics as a function of film thickness of a specimen which was deposited on a substrate. With this method values of λ for DC‐705, DC‐704, and Octoil‐S (diffusion pump oils) were determined to be about 30, 40, and 70 Å, respectively. No clear dependence of the λ on primary‐electron energy was found for 200–1500 eV. These λ values well agree those obtained by means of δ‐η analysis. This fact gives an experimental evidence for the validity of δ‐η analysis in which a film thickness where a break occurs on a δ‐η curve is assumed to correspond to λ.

Cathodic Interaction of an Electrode with Dense Plasma

Vijay K. Rohatgi

J. Appl. Phys. 41, 4826 (1970); http://dx.doi.org/10.1063/1.1658547 (5 pages)

Online Publication Date: 19 November 2003

Full Text: | Download PDF

Show Abstract
Current partitioning at a tungsten cathode in a 1‐atm argon plasma is studied experimentally. Both ions and electrons are found to contribute to the cathode current in this case. The ion current is supplied by the plasma whereas the electron current is controlled by the thermoinic emission laws. The work function of the emitter is reduced due to the presence of an ion space‐charge field in a manner described by the Schottky effect.

Temperature of the Restrike Channels of Exploding Wires

Stig Lundquist and Antonios E. Vlastós

J. Appl. Phys. 41, 4830 (1970); http://dx.doi.org/10.1063/1.1658548 (6 pages) | Cited 5 times

Online Publication Date: 19 November 2003

Full Text: | Download PDF

Show Abstract
The temporal behavior of the temperature, the electron density and the thermal conductivity of the restrike channel of a thin exploding wire were studied, using the electrical conductivity of the restrike channel, which was determined by simultaneous measurements of the current through the channel, the voltage drop cross the channel and the channel radius assuming that the current distribution within the channel was homogeneous. In this study, in which the channel plasma was assumed to be fully and singly ionized, the Spitzer equations for the electrical and thermal conductivity of a fully ionized plasma and a modified pinch relation for the restrike channel were used. The results show:
(a) that the electrical conductivity reaches its maximum before the current maximum on the ledge observed on the voltage oscillograms;
(b) that the temperature and thermal conductivity reach their maxima at the conductivity maximum;
(c) that the electron density reaches its maximum after the conductivity maximum and near the current maximum;
(d) that the maximum values of the electrical conductivity, the temperature, the electron density and the thermal conductivity increase when the energy‐input rate to the channel increases;
(e) that the validity of the assumptions made is in general confirmed.
For restrikes initiated at the exterior of the 13‐cm‐long 0.005‐cm‐diam constantan wires, the maximum values of the temperature and the electron density were found at 5 kV to the about 2×104 °K and 1023 electrons∕m3 respectively, and at 23 kV to be about 4×104 °K and 1025 electrons∕m3, respectively.

Low‐Voltage Arc and Breakdown Effects in Xenon‐Filled Thermionic Diodes

Ralph Forman

J. Appl. Phys. 41, 4836 (1970); http://dx.doi.org/10.1063/1.1658549 (5 pages) | Cited 1 time

Online Publication Date: 19 November 2003

Full Text: | Download PDF

Show Abstract
Breakdown phenomena and the low‐voltage xenon arc have been studied in xenon‐filled thermionic diodes. These measurements were made at gas pressures ranging from 1 Torr to atmospheric pressure and with diodes having interelectrode spacings of 0.05, 0.1, and 0.75 cm. Most of the results were obtained on tubes with a unipotential thoriated‐tungsten cathode operating at approximately 1700°C. The results showed that breakdown in xenon leading to the low‐voltage arc can occur at voltages even lower than the first excitation potential of xenon. No minimum spacing effect was observed; the low‐voltage arc occurred for interelectrode spacings down to 0.05 cm. At 0.05‐cm spacing and a cathode temperature of 1700°C, the low‐voltage xenon arc could be induced over the pressure range 1–500 Torr. Under some conditions of pressure and spacing the low‐voltage xenon arc could be sustained at voltages as low as 1–2 V.

New Superfluid Relativity Gyroscope

D. L. Ensley

J. Appl. Phys. 41, 4840 (1970); http://dx.doi.org/10.1063/1.1658550 (11 pages) | Cited 1 time

Online Publication Date: 19 November 2003

Full Text: | Download PDF

Show Abstract
Experiments have been performed in which mechanical radiation pressure, generated by a megahertz sound field in helium II, successfully supported a metal sphere three dimensionally. Because the field's forces are spherically symmetrical and stable, and because the isothermal environment provided by the quantum coherence properties of helium II eliminates convection currents, only extremely small stray torques act on the suspended mass. It is demonstrated that stray torques less than 10−7 dyn cm were present on the early test model, consistent with the theoretical predictions. Also presented is the predicted performance, based upon these results, of a more refined superfluid gyroscope which demonstrates the feasibility of observing general relativistic gyroscopic motion with a gyroscope rigidly connected to the earth. A proposed experiment to discriminate between Einstein's theory and competing theories of gravitation by measuring the spin‐spin interaction between a gyroscope and the spinning earth is also discussed.

High‐Power Laser Radiation Interaction with Quartz

D. B. Chang, J. E. Drummond, and R. B. Hall

J. Appl. Phys. 41, 4851 (1970); http://dx.doi.org/10.1063/1.1658551 (5 pages) | Cited 18 times

Online Publication Date: 19 November 2003

Full Text: | Download PDF

Show Abstract
Absorption of high‐power CO2 laser radiation on a block of quartz is considered. The SiO2 (quartz) is vaporized and heated and absorption of the incident laser radiation is computed. If the gas is not ionized, the laser energy heats it sufficiently to make it transparent.

Effect of Surface Protrusions on the Current Distribution in a London Superconductor

J. Appel

J. Appl. Phys. 41, 4856 (1970); http://dx.doi.org/10.1063/1.1658552 (4 pages)

Online Publication Date: 19 November 2003

Full Text: | Download PDF

Show Abstract
The current density and the magnetic field strength are calculated in a type‐I superconductor which has the form of a long cylinder with a sinusoidal surface contour. London's and Maxwell's equations are solved with a straightforward perturbation calculation. The amplitude of a protrusion Δ is assumed to be small compared with the penetration depth λ. The results show a sizable variation of current and field near the surface when Δ∕λ and λ∕L (L=wavelength of protrusion) are both ≥0.1.

Magnetization Measurements on Twisted Superconducting Composite Conductors

P. R. Critchlow and B. Zeitlin

J. Appl. Phys. 41, 4860 (1970); http://dx.doi.org/10.1063/1.1658553 (6 pages) | Cited 4 times

Online Publication Date: 19 November 2003

Full Text: | Download PDF

Show Abstract
Magnetization measurements are reported on twisted multistrand NbTi superconducting composites. Data for copper matrix composites when fitted to the theoretical predictions give reasonable values for the matrix resistivity. Data for a CuNi matrix composite and data on the rate of decay of the magnetization at small twist rates do not agree with simple theory. An explanation based on the presence of an untwisted core removes the disagreement. Finally, the data are plotted to show a linear dependence of magnetization on filament diameter over the range 0.00036–0.015 in.

Generation of Harmonics and Subharmonics of the Josephson Oscillation

D. B. Sullivan, Robert L. Peterson, V. E. Kose, and J. E. Zimmerman

J. Appl. Phys. 41, 4865 (1970); http://dx.doi.org/10.1063/1.1658554 (9 pages) | Cited 45 times

Online Publication Date: 19 November 2003

Full Text: | Download PDF

Show Abstract
The observation of harmonics and subharmonics of the Josephson oscillation is shown to be in agreement with a rather simple model of the junction. The generation of harmonics provides an explanation of induced steps in the current‐voltage characteristic which occur at submultiples of the usual induced step voltages. The subharmonic oscillation is seen to be a relaxation‐like process which can be easily understood in terms of a mechanical analog.

Molecular Field Coefficients of Substituted Yttrium Iron Garnets

Gerald F. Dionne

J. Appl. Phys. 41, 4874 (1970); http://dx.doi.org/10.1063/1.1658555 (8 pages) | Cited 68 times

Online Publication Date: 19 November 2003

Full Text: | Download PDF

Show Abstract
By fitting the Néel theory of ferrimagnetism to previously reported magnetic moment‐temperature data for several
math
compositions, where R and Q represent diamagnetic octahedral and tetrahedral substitutions, i.e., Sc3+, In3+, Ga3+, and Al3+, the molecular field coefficients were determined to have the following linear relations with the levels of substitution:
math
for x≤0.70 and y≤1.95. Since both intrasublattice coefficients are affected only by substitutions in the opposite sublattice, a strong similarity to Geller's random canting concepts is apparent. Below the antiferromagnetic transitions it is demonstrated that a clear correlation exists between the decrease in sublattice moment from canting and the reduction in magnitude of the molecular field constant. For both sublattices, the antiferromagnetic transition occurs when Ndd, Naa∼−20 mole∕cm3. This observation lends further credence to the notion that canting sets in immediately upon substitution. To demonstrate the applicability of the above results, magnetic moment‐temperature curves are computed for compositions of {Y3} [Mgx2+Fe2−x] (Six4+Fe3−x) O12 and are shown to compare very favorably with experiment, thus providing a method for predicting the behavior of a wide variety of substituted garnet compositions.

Domain‐Wall Processes in SmCo5 Powders

H. Zijlstra

J. Appl. Phys. 41, 4881 (1970); http://dx.doi.org/10.1063/1.1658556 (5 pages) | Cited 44 times

Online Publication Date: 19 November 2003

Full Text: | Download PDF

Show Abstract
Measurements of minor loops of SmCo5 powders have revealed that wall motion is predominant in the magnetization process. A relation between the reversible susceptibility χ of the minor loops and the coercivity Hc has been found, showing that the coercivity of the investigated material is determined by the pinning of domain walls, rather than nucleation. The relation χHc2=const has been found in a wide range of coercivities obtained by aging of the material. The aging process is interpreted as a decrease of the density of pinning sites, each site retaining its pinning force. Hysteresis loops measured on single particles of a few microns size confirm these interpretations and allow for a refined model of pinned‐wall coercivity of SmCo5 powders.

Noncharacteristic Defects in Thin Films of Cobalt Ferrites

L. C. De Jonghe and G. Thomas

J. Appl. Phys. 41, 4885 (1970); http://dx.doi.org/10.1063/1.1658557 (5 pages) | Cited 1 time

Online Publication Date: 19 November 2003

Full Text: | Download PDF

Show Abstract
High‐voltage transmission electron microscopy has been used to study the structure of thin films of cobalt ferrites of various compositions. Small defects have been identified to result from a combination of chemical polishing used to prepare foils and subsequent radiation damage in the electron microscope. Such defects must be distinguished from the characteristic defects, such as small precipitates, since they are representative only of the preparation and examination techniques.

Stability of Magnets Moving Above a Conducting Plane

Paul B. Bailey and Frederick R. Norwood

J. Appl. Phys. 41, 4890 (1970); http://dx.doi.org/10.1063/1.1658558 (3 pages) | Cited 6 times

Online Publication Date: 19 November 2003

Full Text: | Download PDF

Show Abstract
The equations of motion are obtained for certain magnetic sources moving above a conducting plate and subject to the magnetic forces produced by the eddy currents in the plate. The effects of a small disturbance at time t=0 to a previously steady motion are investigated. It is shown that any small disturbance dies away, leaving the system in essentially the same state of steady motion as before.

Bending Behavior and Tensile Strength of Carbon Fibers

Wendell S. Williams, D. A. Steffens, and Roger Bacon

J. Appl. Phys. 41, 4893 (1970); http://dx.doi.org/10.1063/1.1658559 (9 pages) | Cited 10 times

Online Publication Date: 19 November 2003

Full Text: | Download PDF

Show Abstract
The strength of anisotropic polycrystalline carbon fibers was investigated. Theoretical estimates of the strength of graphite are far higher than observed values for carbonized rayon fibers, and we have searched for an explanation. Internal ``grain boundaries'' in the fibers can account for the reduced strength inasmuch as the fracture appears to be intergranular. The ``grains'' are believed to be axially oriented fibrils, ap‐approximately 500‐Å across. Experimental evidence for some inelastic behavior in carbon fibers at room temperature was obtained from bending experiments on single filaments. The results were interpreted in terms of local ``yielding'' or rupture of cross‐link bonds between adjacent fibrils. The stress at which such ``yielding'' takes place in bending is approximately equal to the failure stress in a tensile test. Although a Griffith model of completely brittle fracture in tensile tests was considered, the possibility that local ``yielding'' might precede tensile fracture seemed more likely. Consideration of the brittle failure model and the localized plastic flow model both lead to the same conclusion: The tensile strength of carbonized rayon fibers is limited by the fibrillar microstructure and cannot be expected to approach the theoretical estimates for graphite single crystals.

Role of Constitutive Equations of Function Type in Modelling Some Commonplace Mechanical Behavior

E. J. Appleby

J. Appl. Phys. 41, 4902 (1970); http://dx.doi.org/10.1063/1.1658560 (11 pages) | Cited 1 time

Online Publication Date: 19 November 2003

Full Text: | Download PDF

Show Abstract
The materials considered in this paper exhibit the following phenomena: (1) a time‐dependent stress approaching a steady value with increasing time in a simple‐tension relaxation test, and (2) a time‐dependent strain rate approaching a steady value with increasing time in a simple‐tension creep test. They are also substantially isotropic and incompressible. Such materials are very common, but, as is shown in this paper, continuum models which will represent them are not. Even very general models such as the Rivilin‐Ericksen and hygrosteric models are shown to be inadequate for this purpose. Models of function type, which do admit the phenomena described above, are considered here within the domain of finite deformations and nonlinear material response. The level of generality of the models is such that the variables appearing in the constitutive equation may be chosen but the form of the function relating them may not. This level forms the groundwork for specialized classification, and leaves open the possibility that a theoretical program of experimentation may be constructed which allows a given material to numerically identify the form of its function within the framework of the general model. As a first step in the search for a continuum model for these materials, the following question arises. Within the level of generality described, what is the simplest model of function type which will represent the material behavior discussed? Re‐expressed: what is the least number of variables which must appear in the constitutive equation, and what are these variables? These questions are answered in this paper.
Page 1 of 3 Pages Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Your Recent History Recent History Help

Recently Viewed

  1. A Powder Technique for the Evaluation of Nonlinear Optical Materials
  2. Magnetoelastic Resonances in Ferrite Memory Cores
  3. Electrical Resistivity of SmAg, SmCu, and SmAu
  4. General Relationship for the Thermal Oxidation of Silicon
  5. Noise Transformation and Cyclotron Waves in Crossed Fields
Go to AIP Home
Copyright © American Institute of Physics
close