Showing papers on "Thermoelastic damping published in 1987"
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01 Jan 1987
TL;DR: In this article, the authors considered the boundary feedback stabilization of Kirchhoff plates subject to weak viscoelastic damping, and the asymptotic stability of the limit systems.
Abstract: Preface 1. Introduction: orientation Background Connection with exact controllability 2. Thin plate models: Kirchhoff model Mindlin-Timoshenko model von Karman model A viscoelastic plate model A linear termoelastic plate model 3. Boundary feedback stabilization of Mindlin-Timoshenko plates: Orientation: existence, uniqueness, and properties of solutions Uniform asymptotic stability of solutions 4. Limits of the Mindlin-Timoshenko system and asymptotic stability of the limit systems: Orientation The limit of the M-T system as KE 0+ The limit of the M-T system as K Study of the Kirchhoff system Uniform asymptotic stability of solutions Limit of the Kirchhoff system as 0+ 5. Uniform stabilization in some nonlinear plate problems: Uniform stabilization of the Kirchhoff system by nonlinear feedback Uniform asymptotic energy estimates for a von Karman plate 6. Boundary feedback stabilization of Kirchhoff plates subject to weak viscoelastic Damping: formulation of the boundary value problem Existence, uniqueness, and properties of solutions Asymptotic energy estimates 7. Uniform asymptotic energy estimates for thermoelastic plates: Orientation Existence, uniqueness, regularity, and strong stability Uniform asymptotic energy estimates Bibliography Index.
624 citations
TL;DR: In this paper, a photoacoustic cell method for obtaining the thermal diffusivity of solids is proposed based on the measurement of the acoustic signal as a function of the modulation frequency in the region where the sample is thermally thick.
Abstract: A minimal‐volume photoacoustic cell method is demonstrated for obtaining the thermal diffusivity of solids. It is based on the measurement of the acoustic signal as a function of the modulation frequency in the region where the sample is thermally thick. The method is tested by using metal, semiconductor, and polymer samples.
198 citations
TL;DR: In this paper, it is shown that the stress dependence of the thermoelastic constant can be explained by the temperature dependence of elastic properties of the material, and excellent agreement between the theoretical predictions and experimental data is achieved.
131 citations
TL;DR: In this paper, the authors derive from the equations of the nonlinear thermoelasticity a certain class of homogenized models of periodic composite materials, based on the methods of nonstandard analysis.
121 citations
TL;DR: In this article, the buckling behavior of moderately thick angle-ply laminates that are simply supported and subject to a uniform temperature rise is analyzed, and an optimization procedure is proposed for the design of fiber-reinforced Laminates having maximum resistance to thermal buckling.
Abstract: The buckling behavior of moderately thick antisymmetric angle-ply laminates that are simply supported and subject to a uniform temperature rise is analyzed. Transverse shear deformation is accounted for by employing the thermoelastic version of the Reissner-Mindlin theory. Results for the classical thin-plate theory are obtained as a special case. Numerical results are presented for fiber-reinforced laminates and show the effects of ply orientation, number of layers, plate thickness, and aspect ratio on the critical buckling temperature. Finally, an optimization procedure is proposed for the design of laminates having maximum resistance to thermal buckling.
117 citations
TL;DR: In this article, the spatially fluctuating strain and stress fields in a random heterogeneous thermoelastic medium are characterized by their mean values and square means in each phase.
Abstract: The spatially fluctuating strain and stress fields in a random heterogeneous thermoelastic medium are characterized by their mean values and square means in each phase. In the present paper the calculation of these quantities, which has been presented in a previous work for the case of a mechanical load only. is extended to include thermal expansion. Besides the derivation of some exact relations between the square means and the analytical properties of the effective thermal expansion coefficient the field fluctuations are calculated within an effective-medium procedure supposing an aggregate topology of the composite. Explicit results obtained for isotropic phases and spherical grain shapes are given in a more convenient representation than in our former work.
67 citations
TL;DR: In this article, thermal, elastic, and feedback analyses are applied to the case of a beam with a distributed thermal actuator, which is capable of producing a thermal gradient across the section of the beam.
Abstract: Thermal, elastic, and feedback analyses are applied to the case of a beam with a distributed thermal actuator. The actuator is capable of producing a thermal gradient across the section of the beam. One candidate for such an actuator uses the Peltier effect, which appears in certain semiconductors. These devices act as heat pumps when a voltage is applied, causing a temperature gradient. It is shown that the thermal gradients can induce deflection in the beam. If the thermal gradients are applied in the proper sense to a vibrating beam, it is possible to increase the vibration damping exhibited by the structure. Experimental results are given for a cantilever beam, whose first vibrational mode damping ratio was increased from 0.81 to 7.4 percent with simple lead compensation.
50 citations
TL;DR: In this paper, the Lagrange identity method with the weight function method was used to obtain the uniqueness and continuous dependence theorems in bounded and exterior domains in linear thermoelasticity.
49 citations
TL;DR: In this paper, the SPATE 8000 was used to demonstrate the mean stress dependence of the thermoelastic constant and its potential application in the measurement of residual stress provided the material has not yielded.
Abstract: The SPATE 8000 thermoelastic stress analyser has been used to demonstrate the mean stress dependence of the thermoelastic constant. This dependence has potential application in the measurement of residual stress provided the material has not yielded.
48 citations
01 Apr 1987
TL;DR: In this article, the amplitude of surface temperature oscillation induced thermoelastically by cyclic loading is analyzed through solutions of the heat-conduction equation, and significant attenuations may occur under typical operating conditions as a result of internal conduction and the presence of surface coatings.
Abstract: The amplitude of surface temperature oscillation induced thermoelastically by cyclic loading is analysed through solutions of the heat-conduction equation. Significant attenuations may occur under typical operating conditions as a result of internal conduction and the presence of surface coatings. Attenuation due to heat loss to the environment will be significant only under rather particular circumstances. Comparison is made with analytical and experimental work of earlier investigators.
40 citations
TL;DR: In this article, the effects of both nonlinear damping and large-deflection are included in the theoretical analysis in an attempt to explain the experimental phenomena of aircraft panels excited at high sound pressure levels; that is the broadening of the strain response peak and the increase of the modal frequency.
TL;DR: In this paper, the problem of determining the states of contacting, rubbing and wearing bodies is resolved using the constitutive equations for materials. But the problem is not addressed in this paper.
01 Jan 1987
TL;DR: In this paper, the authors describe the development of a rigorous theoretical basis for the application of thermoelastic stress analysis to a generalised anisotropic material, and some practical aspects of the approach to fiber composite materials are discussed.
Abstract: The development of thermoelastic stress analysis has provided a unique non-contact method of investigating the stress distribution over the surface of structures and components subject to cyclic loading. The technique has been extensively applied on a qualitative basis to identify areas of high or non-uniform stress in a wide range of structures, including those whose complexity would preclude investigation by more conventional means. However, particularly when applied to fibre composite materials, the derivation of accurate quantitative data requires further development. The present Paper describes the development of a rigorous theoretical basis for the application of thermoelastic stress analysis to a generalised anisotropic material. Some practical aspects of the application of the method to fibre composite materials are then discussed.
TL;DR: In this paper, the influence of microstructure on thermoelastic properties of short carbon fiber reinforced poly(etheretherketone) was investigated and correlation of experimental data with micromechanics model predictions was found to be quite good.
Abstract: Experimental and analytical techniques are employed in the present study to investigate the influence of microstructure on thermoelastic properties of short carbon fiber reinforced poly(etheretherketone). The test specimen geometry is an edge gated, injection molded dogbone tensile bar. Typical of injection molded structures, three distinct layers of fiber orientation were discernable through the sample thickness. The thermoelastic properties of the surface layer (machined from the specimen) are measured for direct correlation with a micromechanics model. In addition to measuring the volume fractions and constituent properties, microstructural features such as fiber aspect ratio and the process-induced fiber orientation distribution are quantified. Correlation of experimental data with micromechanics model predictions is found to be quite good.
TL;DR: In this article, a theory for combined shear and compressional damping effects of contrained layered beam structures with complicated cross section areas was formulated for some selected theoretical examples, and the calculation results indicated that the loss factor values of these beams are larger over a wider frequency range than could be expected from corresponding shear damping effect only or compression damping treatment only.
01 Apr 1987
TL;DR: The equations relating the output of the SPATE* 8000 thermoelastic stress analysis system to the strains in multidirectional laminated fiber composites have been developed.
Abstract: The equations relating the output of the SPATE* 8000 thermoelastic stress analysis system to the strains in multidirectional laminated fibre composites have been developed. The system has been calibrated for use with a particular carbon fibre/epoxy resin material. For multidirectional laminates under a generalised state of stress, it has been observed that the sensitivity of the SPATE output to the various strain components differs significantly such that even the qualitative interpretation of SPATE scans is difficult. However, there are a number of special cases which are applicable to practical structural laminates for which the interpretation of scans is greatly simplified.
TL;DR: In this paper, the Von Mises stresses have been determined throughout the crystal and the local effective resolved shear stress leading to dislocation generation and movement was determined by subtracting reported values of yield stress and critical resolved Shear stress from the maximum resolved Shears stress, where high dislocation densities occur in the central region and near the outside surface of the crystal in agreement with reported observations of etch pit density distributions in GaAs.
01 Jan 1987
TL;DR: In this paper, a shape design sensitivity analysis of thermoelastic solids is done by using the material derivative idea and the adjoint variable method, and boundary element methods are proposed for spatial discretization of system of equations and relevant functionals.
Abstract: Shape design sensitivity analysis of thermoelastic solids is done by using the material derivative idea and the adjoint variable method. Boundary element methods are proposed for spatial discretization of system of equations and relevant functionals.
TL;DR: In this article, a solution for the transient thermal stresses due to a local source of heat that moves at constant speed over the surface of an infinite elastic slab is given, and the transient temperature distribution is obtained by means of the Fourier and Laplace transforms, and associated thermal stresses are obtained by making use of the thermoelastic displacement function and the Galerkin function.
Abstract: A solution is given for the transient thermal stresses due to a local source of heat that moves at constant speed over the surface of an infinite elastic slab. The transient temperature distribution is obtained by means of the Fourier and Laplace transforms, and the associated thermal stresses are obtained by making use of the thermoelastic displacement function and the Galerkin function.
TL;DR: In this article, the authors deal with the propagation of thermoelastic waves in a thin plate occupying the Cartesian space and present a mathematical analysis for the wave motion characteristics of the plate.
Abstract: In the present work we deal with the propagation of thermoelastic waves in a thin plate occupying the Cartesian space (x
1∈[−∞, +∞],x
2∈[−α, +α],x
3∈[−δ, +δ]). The analysis is based on the generalized theory of thermoelasticity proposed by Lord and Shulman modified for plane stress problems. A mathematical analysis is presented to study the wave motion characteristics of the plate and the proposed analysis is applied for the special cases of very short and very long waves.
TL;DR: In this article, a model for the formation of dislocations produced by the martensitic transformation of β phases into 18R (or 9R) structures in thermoelastic alloys is proposed.
TL;DR: In this article, a 3D flat plate with small thickness is submitted to an arbitrary system of initial and loading conditions and the limits of the displacement, stress, and temperature fields as the thickness approaches zero are investigated.
Abstract: Introduction. The derivation of the mechanical behavior of a flat plate as the limit behavior of a three-dimensional flat solid whose thickness tends to zero is a well-established theory since the works of Goldenveizer [G] or Ciarlet and Destuynder [CD1], Due attention has been paid to the static response of such plates for various linear or nonlinear mechanical behaviors (Ciarlet-Destuynder [CD1, CD2], Ciarlet [C], Blanchard-Ciarlet [BC]). Much less attention, however, has been devoted to the dynamic response of flat plates from a similar standpoint. The linearly elastic case was considered in Raoult [Rl, R2], but we are not aware of any further work in that direction. The present study is devoted to the dynamic behavior of a three-dimensional linearly thermoelastic flat plate. Specifically, a three-dimensional flat plate with small thickness is submitted to an arbitrary system of initial and loading conditions. The limits of the displacement, stress, and temperature fields as the thickness approaches zero are investigated. Thermoelastic behavior is characterized by a coupling between the mechanical equations of motion and the \"energy\" equation. The limiting procedure is seriously affected by the presence of the coupling terms. The initial conditions are seen to play an essential role in the analysis. In particular, a change of initial condition generally occurs for the temperature field. A similar phenomenon appears in the homogenization of a thermoelastic composite (Francfort [F]). These concurring results seem to indicate that such shifts in initial data are closely linked to any kind of asymptotic problem for coupled systems. The first section is very short and entirely devoted to notation and basic definitions. In the second section, the problem under investigation is formulated in a mathematical framework. It is then rescaled in the usual manner (Ciarlet-Destuynder [CD1]) so as to obtain a family of problems indexed by the thickness of the plate and defined on a fixed domain.
TL;DR: In this article, a finite-element formulation of a coupled thermoelastic-plastic stress analysis of solid structures is presented, which is based on a selected phenomenological energy dissipation model and elasticplastic constitutive equations for both isotropic and kinematic hardening schemes.
Abstract: This paper presents a finite-element formulation of a coupled thermoelastic-plastic stress analysis of solid structures. The formulation is based on a selected phenomenological energy dissipation model and elastic-plastic constitutive equations for both isotropic and kinematic hardening schemes. Numerical illustrations involving this coupling effect on a uniaxially loaded solid rod and on a thick-walled cylinder subject to internal pressure are included, using assumed values of dissipation factors. Temperature rises induced by one mechanical load cycle in both cases were computed. Numerical results indicate that the maximum effective strain in the solids from an uncoupled analysis can be as much as 10% larger than that from a coupled analysis under the same mechanical load. Coupled thermomechanical analysis is thus considered to be significant. The present method may readily be incorporated into a thermoelastic-plastic finite-element analysis and used to predict the healing of machine components produced ...
TL;DR: In this paper, the effect of coupled thermoelasticity on the propagation of Rayleigh-Lamb waves in an infinite plate is investigated. But the authors only consider the case of a plate bounded by traction-free surfaces.
TL;DR: In this article, the propagation of thermoelastic waves in a waveguide occupying the Cartesian space x 1 ϵ [0, L ], x 2 ϵ[− H, + H ], x 3 ϵ] [− ∞, + ∞] is discussed.
TL;DR: In this article, the phenomenological theory of isothermal rubber elasticity for homogeneous biaxial deformations is extended to the thermoelastic case and new general results are established and then applied to consideration of strain induced volume dilation, the notion of anisotropy of compressibility and the energetic contribution to the stress.
TL;DR: In this article, a procedure for analyzing the damping in a multielement space structure connected by joints is described, in which distributed material damping and discrete nonlinear joint properties are incorporated into a linear analysis.
TL;DR: In this paper, a domain of influence theorem, work and energy theorem, and reciprocity theorem are proved for a linear anisotropic nonhomogeneous temperature-rate-dependent thermoelastic unbounded body.
Abstract: A domain of influence theorem, work and energy theorem, and reciprocity theorem are proved for a linear anisotropic nonhomogeneous temperature-rate-dependent thermoelastic unbounded body. The theorems cover the case where the constitutive fields may attain unbounded values at infinity, and they are based on a hypothesis from which it follows that a thermoelastic disturbance produced by an external ther-momechanical load of a bounded support cannot invade the whole body in a finite time