Showing papers on "Thermoelastic damping published in 1973"
TL;DR: In this paper, the problem of determining overall thermoelastic moduli of some solid composites is discussed, where the phases may be arbitrarily anisotropic and the volume concentrations are arbitrary.
Abstract: The problem of determining overall thermoelastic moduli of some solid composites is discussed. The phases may be arbitrarily anisotropic. One phase is required to be a matrix and the remainder are required to be aligned ellipsoidal inclusions. The volume concentrations are arbitrary. Some exact results are obtained for a binary composite. In the general case the self-consistent method is used to estimate the overall moduli. The general results are shown to reduce to those known for an isotropic dispersion of spheres.
167 citations
TL;DR: In this article, the effects of structural joints on the damping of built-up structures are discussed, and the energy dissipation mechanisms associated with squeezing, rocking, and shearing motions are discussed for simple joints that are dry, lubricated, or provided with viscoelastic inserts.
148 citations
TL;DR: In particular, the critical condition for obtaining the ferroelastic loop can be experimentally determined by assuming a critical stress, which is termed "ferro-elastic limit", which lies in the region 6 Kg/mm- in the Au-Cd alloy as mentioned in this paper.
Abstract: Thermoelastic martensitic transformation has been studied by the analysis of stress-strain curves in binary Au-Cd alloys, containing 46·5, 47·5, 48·5, 49, 49·5, and 50 at. % Cd, respectively. The pseudoelastic characteristics, i.e. superelastic and ferroelastic behaviour upon tension compression test and that the origin of the shape memory effect bears a close relation to the ferroelastic loop, have been explained on the basis of the lattice softening, that is. the shear elastic constant, C′ = (C11-C12)/2, decreases toward zero in the vicinity of the transition temperature. In particular the critical condition for obtaining the ferroelastic loop can be experimentally determined by assuming a critical stress, which is termed ‘ferroelastic limit’. The ferroelastic limit may depend upon the elastic anisotropy of alloys and lies in the region 6 Kg/mm- in the Au-Cd alloy.
144 citations
TL;DR: In this article, a theory of spallation of a brittle thermoelastic body and the interaction between propagating waves and accumulated damage was developed to predict the spall damage on the elastic stiffness and thermal conductivity of the material.
Abstract: In this article we develop a theory of spallation of a brittle thermoelastic body, and of the interaction between propagating waves and accumulated damage. This theory is applied to the prediction of the effect of spall damage on the elastic stiffness and thermal conductivity of the material.
121 citations
TL;DR: The temperature dependence of all elastic constants of cubic potassium cyanide has been measured by ultrasonic methods in the range from -105.4 to 181.5°C as discussed by the authors.
109 citations
TL;DR: In this paper, a review of the use of rotational isomeric state theory in the interpretation and prediction of a variety of configurationally dependent properties of rubber-like elasticity is presented.
Abstract: Thermoelastic measurements and their interpretation by means of rotational isomeric state theory provide a great deal of insight into both thermodynamic and molecular aspects of rubberlike elasticity. Furthermore, conformational energies obtained in part from thermoelastic studies can in turn be used in the interpretation and even prediction of a variety of configurationally dependent properties of chain molecules, as is shown in many of the theoretical investigations cited in Sections IV and VII of this review.
88 citations
57 citations
TL;DR: In this paper, the mean waves in a medium with random inhomogeneities are studied within the theory of linear thermoelasticity under the assumption of small random fluctuations approximate integro-differential equations governing the mean displacement and temperature fields.
33 citations
TL;DR: In this paper, the authors investigated the propagation of thermoelastic waves propagated in non-simple media and studied the distinction between propagation in simple and nonsimple media, respectively.
Abstract: The present paper is an attempt to investigate the propagation of thermoelastic waves propagated in non-simple media and study the distinction between propagation in simple and nonsimple media. Plane progressive waves and Rayleigh waves have been discussed.
23 citations
TL;DR: In this paper, a model based on the deformable elastic shell model for diatomic elastic shells is presented. But the model is not suitable for the case of diatomic solids with multiple temperature.
20 citations
TL;DR: In this article, the elastic constants of lead, barium, and strontium nitrates in the range 4-300 K were investigated with great accuracy using resonance and pulse-echo ultrasonic methods.
Abstract: Variation in the elastic constants of lead, barium, and strontium nitrates in the range 4–300 K has been investigated with great accuracy using resonance and pulse‐echo ultrasonic methods. The thermoelastic behavior of the three nitrates are compared. Strontium nitrate and lead nitrate especially appear to be much more anharmonic than barium nitrate.
TL;DR: In this article, three samples of natural rubber were crosslinked in n-decane solution, and a thermodynamic investigation was made of the elastic behaviour of the samples in simple extension.
TL;DR: In this article, a study of the spectrum of plane harmonic wave propagation in a heat-conducting continuum is presented, where the authors define an algebraic function, called the modal function, whose regular branches specify the slownesses of the possible modes of harmonic wave propagations as functions of the frequency.
Abstract: A study is made of the secular equation governing the propagation of plane harmonic waves of small amplitude in a continuum which is able to conduct heat. This equation defines an algebraic function, called the modal function, whose regular branches specify the slownesses of the possible modes of harmonic wave propagation as functions of the frequency. At each extreme of the frequency range one mode is diffusive in type and the others wave-like, and we suppose here that there is a single wave-like mode which produces changes of temperature. In this case the mode which is diffusive in type at low frequencies is wave-like or diffusive in the high-frequency limit according as the thermoelastic coupling constant (a dimensionless measure of the strength of thermo-mechanical interaction in the continuum) does or does not exceed unity. This property is shown to have a simple interpretation in terms of a Riemann surface of the modal function. The results obtained are quite general, referring to principal longitudinal waves in a homogeneously deformed isotropic heat-conducting elastic material, to dilatational disturbances of a stress-free configuration of such a material, and to acoustic waves in a heat-conducting inviscid fluid.
TL;DR: In this article, an analysis of published experimental and theoretical slip-line field results for the metal cutting process suggests that, when the tool and workpiece are of high elastic modulus, a reasonable first approximation to the rake-face loading will consist of uniformly distributed normal and tangential stresses over the contact length.
Abstract: An analysis of published experimental and theoretical slip-line field results for the metal cutting process suggests that, when the tool and workpiece are of high elastic modulus, a reasonable first approximation to the rake-face loading will consist of uniformly distributed normal and tangential stresses over the contact length. An indication of the form of the stress distribution at the tip of a cutting tool is therefore obtained from an isothermal–elastic solution for a two-dimensional infinite wedge, loaded antisymmetrically by uniform normal and tangential stresses adjacent to the apex.Only a preliminary assessment of the results is made, in relation to cutting tool wear and fracture problems, since a more detailed assessment will await a complete thermoelastic solution to the problem.
TL;DR: In this paper, a solution for a thermoelastic problem concerning a strip is obtained by the method of dual integral equations under the assumption that the crack is parallel to the edges of the strip.
TL;DR: In this article, a linear viscoelastic solid creeping under a constant stress is changed abruptly from T0 to T and the ratio of the instantaneous creep rates at the time of the T-jump is illustrated.
Abstract: IF the temperature of a linear viscoelastic solid creeping under a constant stress is changed abruptly from T0 to T then the ratio of the instantaneous creep rates at the time of the T-jump is illustration in which illustration β is a parameter which depends on the viscoelastic properties of the solid1, κ a parameter which accounts for the perturbation due to thermoelastic stresses generated by the T-jump2 and ΔH the activation energy for creep If β=κ=1, equation (1) reduces to the Dorn equation3, illustration so that ΔH may be determined from a measurement of eT0 and eT Here we show how ΔH may be determined when κ=1 but β takes values greater or less than unity depending on the direction of the T-jump
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TL;DR: In this article, it was shown that the energy contribution to rubber elasticity (fe/f) can be readily calculated from the temperature coefficient of shear modulus, and the value of f e /f for poly(n-butyl acrylate) was in excellent agreement with that determined in uniaxial elongation.
Abstract: Thermoelastic measurements were carried out for acrylic copolymers in simple shear. Samples were synthesized by UV photopolymerization. It is shown that the energy contribution to rubber elasticity (fe/f) can be readily calculated from the temperature coefficient of shear modulus. The value of f e /f for poly(n-butyl acrylate) thus obtained is in excellent agreement with that determined in uniaxial elongation. Energy contributions were found to vary as a function of temperature. Values of f e/f for the copolymers are intermediate between those of the parent homo-polymers as long as thermoelastic measurements were carried out at a temperature sufficiently greater than the glass transition temperature of the polymer.
TL;DR: Using the generalised dynamical theory of thermoelasticity, a two dimensional harmonic problem for a cylinder has also been considered and small amplitude vibrations of the circular cylinder have been studied further.
Abstract: Using the generalised dynamical theory of thermoelasticity, thermoelastic problem for an isotropic infinite circular cylinder has been solved by approximate techniques. A two dimensional harmonic problem for a cylinder has also been considered and small amplitude vibrations of the circular cylinder have been studied further.
TL;DR: In this article, the shaft is modeled as a hollow cylinder of finite length and the transient heat conduction equation was used in conjunction with Goodiers formula for the thermoelastic bow.
TL;DR: In this paper, the authors evaluated the attenuation suffered by compressional and shear acoustic waves propagating along the $100 and $110 directions from measured third-order elastic moduli for germanium metal.
Abstract: Attenuation suffered by compressional and shear acoustic waves propagating along the $〈100〉$ and $〈110〉$ directions has been evaluated from measured third-order elastic moduli for germanium metal in its pure and doped states at room temperature. The present results for pure germanium are in excellent agreement with previous attenuation measurements. As an effect of doping, an increase in phonon viscosity and in thermoelastic attenuation is observed. The resisting force acting against moving dislocations of both types is also presented.
Proceedings Article•
01 Sep 1973TL;DR: In this article, a thermoelastic stress analysis procedure is reported for predicting the thermally induced stresses and failures in silicon solar cell arrays, which is a prerequisite for the characterization of the temperature-dependent thermal and mechanical properties of the solar cell materials.
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.
TL;DR: In this article, the authors considered the inclusion geometry in the lower-order correlation functions, that is, those of order two and less, and derived upper and lower bounds and improvements on these bounds for the elastic constants.
Abstract: The method proposed by the authors in their earlier paper on thermal conductivity has been utilized to estimate the effective elastic constants and the coefficient of thermal expansion of a statistically isotropic heterogeneous medium. The method considers the inclusion geometry in the lower-order correlation functions, that is, those of order two and less. The upper and lower bounds and the improvements on these bounds have been derived for the elastic constants. Expressions containing the two-point correlation functions are also derived for the coefficient of thermal expansion and the related stress tensor. The theoretical values are compared with the experimental results and the comparison can be considered satisfactory in view of the difficulty in obtaining perfectly isotropic distribution experimentally and the sensitivity of the final properties to mild anisotropy when the difference in the constituent properties is large as in the case of Araldite and copper. The theoretical results for the aluminium-copper system show that convergence of the bounds is extremely good when properties of the constituents are of the same order.
TL;DR: In this paper, the authors studied the thermal stress and displacement fields in an infinite elastic medium weakened by cracks occupying the space interior to two coplanar circular regions with equal radii, and the problem was reduced to the determination of the solution of infinite sets of Fredholm integral equations.
TL;DR: In this paper, the authors considered the case of a circular region being subjected to a uniform heat flow and considered how the ratio of the radius of the heated region to the plate thickness affects on their distributions.
TL;DR: In this paper, it was shown that Mehta and Chaudhry's paper is in error, and their problem reduces to the corresponding one in isothermal elasticity, whose solution is well known.
TL;DR: In this article, a dynamical continuum theory for laminated composite beams is developed, which is consistently constructed within the frame of the three-dimensional theory of linear, nonisothermal, anisotropic, coupled viscoelasticity.
Abstract: A dynamical continuum theory is developed for laminated composite beams. Starting with an assumed displacement- and temperature field, the one-dimensional approximate theory is consistently constructed within the frame of the three-dimensional theory of linear, nonisothermal, anisotropic, coupled viscoelasticity. Each constituent of the beam may possess different constant thickness and mechanical properties. All dynamic interactions between the adjacent constituents are included. Further, the effects of transverse shear and normal strains and rotatory inertia as well as those of cross-sectional distortion are all taken into account. The resulting equations consist of the macroscopic beam equations of motion and heat conduction, the kinematical relations, the initial and boundary conditions and the constitutive equations, and they govern the extensional, flexural and torsional motions of laminated composite beams. The special cases of constituents which made of either isotropic thermoviscoelastic or anisotropic thermoelastic materials are discussed briefly.