Showing papers on "Thermoelastic damping published in 1991"
TL;DR: In this article, effective elastic moduli and thermal expansion coefficient of spherical particle composites with imperfect interfaces are evaluated on the basis of the composite spheres assemblage and generalized self-consistent scheme models.
Abstract: Effective elastic moduli and thermal expansion coefficient of spherical particle composites with imperfect interfaces are evaluated on the basis of the composite spheres assemblage and generalized self-consistent scheme models. Imperfect interface is defined in terms of interface displacement discontinuities which are linearly related to interface tractions in terms of spring constant parameters. In the case of presence of interphase these parameters are evaluated in terms of interphase characteristics.
273 citations
TL;DR: In this article, the current state of thermoelastic problems in materials with temperature dependent properties is described for analytical treatments, and a perturbation method to analyze the thermelastic problems, and an new treatment for heat conduction problem in the non-homogeneous body.
Abstract: the current state of thermoelastic problems in materials with temperature dependent properties is described for analytical treatments. We discuss a perturbation method to analyze the thermelastic problems, and an new treatment for heat conduction problem in the non-homogeneous body. Thermoelastic problems in Functional Gradient Plates(FGP) are treated for a steady state and an unsteady state. Thermoelastic problems in the FGP with a crack are also considered.
244 citations
TL;DR: In this paper, the existence of diagonal symmetry in estimates of overall stiffness tensors of heterogeneous media is examined for several micromechanical models, and the equivalence of two possible approaches to evaluation of the overall thermal stress and strain tensors is raised.
Abstract: T he existence of diagonal symmetry in estimates of overall stiffness tensors of heterogeneous media is examined for several micromechanical models. The dilute approximation gives symmetric estimates for all matrix-based multiphase media. The Mori-Tanaka and the self-consistent methods do so for all two-phase systems, but only for those multiphase systems where the dispersed inclusions have a similar shape and alignment. However, the differential schemes associated with the self-consistent method can predict diagonally symmetric overall stiffness and compliance for multiphase systems of arbitrary phase geometry. A related question is raised about the equivalence of two possible approaches to evaluation of the overall thermal stress and strain tensors. A direct estimate follows from each of the above models, whereas L evin 's results [ Mechanics of Solids 2 , 58 (1967)] permit an indirect evaluation in terms of the estimated overall mechanical properties or concentration factors and phase thermoelastic moduli. These two results are shown to coincide for those systems and models which return diagonally symmetric estimates of the overall stiffness. Finally, model predictions of the overall elastic symmetry of composite media are discussed with regard to the spatial distribution of the phases.
188 citations
Book•
01 Jan 1991
TL;DR: Harwood et al. as discussed by the authors introduced the concept of thermo-elastic stress analysis and applied it to fracture mechanics, P.Stanley variable-amplitude loading, N.T.Potter post-processing of SPATE data, J.K.McKelvie and A.Cummings the thermoelastic effect -a higher order consideration, A.G.Beghi TSA signal processing and data collection.
Abstract: An introduction to thermoelastic stress analysis, N.Harwood et al thermal analysis of deformation mechanisms using a contacting technique, M.G.Beghi TSA signal processing and data collection, B.R.Boyce signal attenuation duw to internal and external factors, J.McKelvie and A.K.MacKenzie application of SPATE in fracture mechanics, P.Stanley variable-amplitude loading, N.Harwood and W.M.Cummings the thermoelastic effect - a higher order consideration, A.K.Wong thermoelastic analysis of anisotropic materials, R.T.Potter post-processing of SPATE data, J.T.Boyle.
151 citations
TL;DR: In this article, the damping properties of high-damping metals and alloys are characterized using a variety of equipment adapted to different modes of vibration and their overtones.
Abstract: High-Damping Metals (HIDAMETS) are the physical metallurgist’s answer to unwanted noise and vibrations. However, the characterization of the damping properties of metals and alloys is neither simple nor straightforward. This is mainly because the damping mechanisms involved depend upon the stress-induced movement of defects in the metal in question which, in turn, implies a dependence upon the microstructure (thermomechanical history) of the sample. To properly characterize the damping performance of a HIDAMET in a well-defined structural state, one must measure the mechanical damping as a function of vibration frequency, temperature, vibration strain amplitude, and static bias load over the ranges of these variables to be encountered in the application in question. This requires the use of a variety of equipment adapted to different modes of vibration and their overtones, especially when the damping is nonlinear (amplitude-dependent). Our approach to this problem is described and illustrated by test results obtained on several HIDAMETS.
123 citations
Book•
01 Jan 1991
TL;DR: In this paper, the authors present theoretical foundations of ductile fracture numerical studies on stable crack growth and integral calculations in mixed-mode elastic-plastic crack problems using FEM and micro-structural models.
Abstract: Fundamentals of ductile fracture numerical studies on stable crack growth j integral calculations in mixed-mode elastic - plastic crack problems j integral for thin shells on stress relaxation at the tip of a crack under normal tension assessment of crack initiation and crack growth in multiphased materials using FEM and microstructural models an energy analysis of elastic - plastic fracture on the crack extension energy rate in elastic - plastic bodies thermoelastic - plastic FEM-analysis of a semi-elliptical surface crack in a cylinder under non-axi-symmetric cooling finite element fracture simulation of A533B steel sheet specimens on the criteria of fracture mechanics and local parameters based on the energy - momentum tensor (part contents)
111 citations
TL;DR: In this article, an implicit-implicit staggered procedure for the finite element solution of fully coupled thermoelasticity transient problems is proposed, which is stabilized with a semi-algebraic augmentation technique.
Abstract: An unconditionally stable second order accurate implicit-implicit staggered procedure for the finite element solution of fully coupled thermoelasticity transient problems is proposed. The procedure is stabilized with a semi-algebraic augmentation technique. A comparative cost analysis reveals the superiority of the proposed computational strategy to other conventional staggered procedures. Numerical examples of one- and two-dimensional thermomechanical coupled problems demonstrate the accuracy of the proposed numerical solution algorithm.
102 citations
TL;DR: A detailed theoretical and experimental study of laser-induced density and temperature changes, and flow reorientation effects in the nematic and smectic phases of liquid crystals is presented in this article.
Abstract: A detailed theoretical and experimental study of laser‐induced density and temperature changes, and flow‐reorientation effects in the nematic and smectic phases of liquid crystals is presented. Using picosecond lasers, the initial nanosecond dynamics of the photoinduced density waves, temperature buildup, and relaxations are temporally resolved. The experimentally observed relaxation phenomena and time scales are in good agreement with the theoretical expressions obtained by analytical solutions of the coupled hydrodynamical equations describing these fundamental mechanisms. Our new measurement and theory provide a quantitative account of the relative contribution from the electrostrictive and thermoelastic contributions that had not been presented in previous studies. Our study of the smectic phase has conclusively established the mechanism for the formation of erasable and permanent grating effects under short‐laser‐pulse excitation as laser‐induced electrostrictive and thermoelastic effects.
84 citations
TL;DR: In this article, the authors extended the analysis of journal bearings to include provisions for the shaft thermal dilation as well as the bush thermoelastic deformation, and provided numerical solutions using a combination of the finite difference and finite element methods.
Abstract: Thermohydrodynamic analysis of journal bearings is extended to include provisions for the shaft thermal dilation as well as the bush thermoelastic deformation. Numerical solutions using a combination of the finite difference and finite element methods are presented. Comparison of the simulation results with those obtained experimentally yielded satisfactory agreement. It was found that while the shaft and bush thermal expansion and the bush elastic deformation are individually important, the collective effect of these factors must be considered for meaningful end results.
79 citations
01 Jul 1991
TL;DR: In this paper, the thermal effects of interface pressure distribution may be divided into bulk temperature effects, such as brake drum expansion and brake disc coning, and its macroscopic thermal effects such as heat spotting, and suggests how the two are related through the process of thermoelastic instability.
Abstract: Heat generated at the sliding interface between the friction material and the mating surface of a friction brake is not uniformly distributed over the sliding surfaces but depends upon the local interface pressure. Many thermal problems associated with brake friction pairs, including performance variation (fade, speed sensitivity) and rotor damage (heat spotting and thermal cracking) can be analysed in terms of localized frictional heat generation as discussed here.This paper describes how the thermal effects of interface pressure distribution may be divided into bulk temperature effects, such as brake drum expansion and brake disc coning, and its macroscopic thermal effects, such as heat spotting, and suggests how the two are related through the process of thermoelastic instability. The results of analyses, using finite element methods, indicate that uniform friction interface pressure is very important in minimizing brake thermal problems. However, more basic research in the area of interface contact an...
71 citations
TL;DR: In this article, an adjoint approach is presented to formulate explicit sensitivities for a general functional associated with a nonlinear, dynamic, thermoelastic system, which is defined in terms of the design fields and the implicit response fields: displacement, temperature, strain, temperature gradient, stress, heat flux vector, reaction force, and reaction surface flux.
Abstract: An adjoint approach is presented to formulate explicit sensitivities for a general functional associated with a nonlinear, dynamic, thermoelastic system. Uncoupled thermoelastic response and small-deformation behavior are assumed. The formulation uses the Lagrange multiplier method to define an adjoint system, the convolution operator to incorporate transient effects, and domain parameterization to describe shape variations. Variations of the functional are expressed in explicit form with respect to perturbations of the design fields: structural shape, material properties, applied loads, prescribed boundary conditions, and initial conditions. The functional is defined in terms of the design fields and the implicit response fields: displacement, temperature, strain, temperature gradient, stress, heat flux vector, reaction force, and reaction surface flux. In an example problem, the finite element method is used to evaluate the real and adjoint responses and the shape sensitivities for a tank design problem. The tank is modeled as a nonlinear, quasistatic, uncoupled, thermoelastic system.
TL;DR: In this paper, physically-based graphics models of non-rigid objects capable of heat conduction, thermoelasticity, melting and fluid-like behaviour in the molten state were developed.
Abstract: We develop physically-based graphics models of non-rigid objects capable of heat conduction, thermoelasticity, melting and fluid-like behaviour in the molten state. These deformable models feature non-rigid dynamics governed by Lagrangian equations of motion and conductive heat transfer governed by the heat equation for non-homogeneous, non-isotropic media. In its solid state, the discretized model is an assembly of hexahedral finite elements in which thermoelastic units interconnect particles situated in a lattice. The stiffness of a thermoelastic unit decreases as its temperature increases, and the unit fuses when its temperature exceeds the melting point. The molten state of the model involves a molecular dynamics simulation in which ‘fluid’ particles that have broken free from the lattice interact through long-range attraction forces and short-range repulsion forces. We present a physically-based animation of a thermoelastic model in a simulated physical world populated by hot constraint surfaces.
TL;DR: In this article, the authors analyzed and presented the complete high-temperature data for six minerals measured in the University of California, Los Angeles, Mineral Physics Laboratory and found no significant differences in the thermoelastic parameters for the calcium rich minerals when compared with the calcium deficient minerals.
Abstract: The complete high-temperature data for six minerals measured in the University of California, Los Angeles, Mineral Physics Laboratory are analyzed and presented as a group. These minerals include CaO and a calcium rich garnet, grossular. We find no significant differences in the thermoelastic parameters for the calcium rich minerals when compared with the calcium deficient minerals. Evidence of anharmonicity is shown in the specific heat, CV, of corundum, forsterite, pyrope, and grossular garnet, but no evidence is found for the case of MgO and CaO. The patterns for the thermoelastic parameter γ show that in general γ decreases with temperature T and that γ at constant volume always decreases rather markedly with T. The thermoelastic parameters, δT, δS, and αKT tend to remain independent of T at high T (above Θ), whereas they are not independent of T near room temperature. The thermal pressure at P = 0 is quite linear with T at temperatures above Θ for all six minerals. We find no evidence of anharmonic behavoir for the thermoelastic parameters of forsterite, correcting an earlier report by Anderson and Suzuki (1983) that anharmonicity appeared in γ, δT;, δS, and αKT at high T for this mineral.
TL;DR: In this paper, a non-adiabatic thermoelastic theory for a general laminated composite plate is formulated, which successfully explains the observed dependency of measured thermo-elastic response on ply lay-up configuration and loading frequency, and provides an insight to the mechanics of interlaminar heat transfer.
TL;DR: In this paper, a theory for binary mixtures of thermoelastic solids is presented in which the independent constitutive variables are the displacement gradients, relative displacement, temperature, and temperature gradient.
Abstract: A theory for binary mixtures of thermoelastic solids is presented in which the independent constitutive variables are the displacement gradients, relative displacement, temperature, and temperature gradient. The theory is linearized, and a uniqueness result is established. 13 refs.
TL;DR: In this article, the effect of viscoelastic interphase between elastic constituents of composites is investigated on the basis of a correspondence principle relating effective elastic and visco-elastic properties.
TL;DR: In this article, an exact solution for the elastic response of a cylindrical cross-ply laminated panel subject to mechanical loading and temperature variation is derived, where the three-dimensional equilibrium equations are reduced to a system of coupled ordinary differential equations, which are then solved using the power series method.
Abstract: An exact solution for the elastic response of a cylindrical cross-ply laminated panel subject to mechanical loading and temperature variation is derived. The three-dimensional equilibrium equations, written in terms of displacements, are reduced to a system of coupled ordinary differential equations, which are then solved using the power series method. Numerical results are presented for graphite/epoxy composites.
TL;DR: In this article, a three-dimensional finite element method is developed for the characterization of the effects of three dimensional states of stress on the damping of laminated composites, where the effect of interlaminar stresses on laminate damping is studied by varying the fiber orientation and the laminate width-to-thickness ratio.
TL;DR: A quasi-steady state, integrated system model describing high temperature heat transfer, solidification, and the action of capillarity in the Czochralski crystal growth process for silicon is applied as a design tool to find optimum processing conditions and system configurations as discussed by the authors.
TL;DR: In this paper, an adjoint approach derived from the reciprocal theorem is presented for the sensitivity analysis of linear dynamic thermoelastic systems, where the variation of a general response functional is expressed in explicit form with respect to variations of the design fields which consist of the material properties, applied loads, prescribed boundary, initial conditions, and the structural shape.
TL;DR: In this article, the authors studied the generation of stress and magnetic fields in a solid cylindrical continuum subjected to ramp-type heating on its surface when the cylinder and its adjoining vacuum is subjected to a uniform axial magnetic field.
TL;DR: In this article, the dynamic thermoelastic problem in a sphere is decomposed into a particular form of dynamic stress problem corresponding to the thermo-elastic displacement potential and a homogeneous form corresponding to stress functions.
Abstract: Adopting the Goodier's concept, the dynamic thermoelastic problem in a sphere is decomposed into a particular form of dynamic stress problem corresponding to the thermoelastic displacement potential and the homogeneous form of dynamic stress problem corresponding to the stress functions. Applying the ray theroy to the homogeneous form, we obtain the general solution for transient waves induced by sudden heating
TL;DR: In this paper, the authors compared their own results to previous numerical results in their publications so far, and provided a very handy form for program testing in the case of sudden and ramp-type surface heating.
Abstract: The thermal shock problem of a half-space is frequently used as a test example for checking computer programs which are suitable for solving thermoelastic problems. As there are no exact solutions for the problem formulated on the basis of complicated models, authors have compared their own results to previous numerical results in their publications so far. In the present paper six thermoelastic models are investigated. Curves of temperature, displacement and stress fields arising as a result of sudden and ramp-type surface heating are given in a very handy form for program testing. A thorough analysis of elastic and thermal waves is also included.
01 Jan 1991
TL;DR: In this paper, the effect of thin interphase between constituents of a composite material is described in terms of imperfect interface conditions which involve interface parameters, and their effect on the mechanical properties of composites is evaluated on the basis of the composite cylinder/spheres assemblage models.
Abstract: The effect of thin interphase between constituents of a composite material is described in terms of imperfect interface conditions which involve interface parameters. Elastic, viscoelastic and elastoplastic interphases are considered and their effect on the mechanical properties of composites is evaluated on the basis of the composite cylinder/spheres assemblage models and the generalized self consistent scheme approximation.
TL;DR: In this paper, the mechanical damping properties of a series of die-cast zinc-aluminum alloys are analyzed and it is shown that the damping consists of two components: a thermoelastic relaxation and the low-temperature tail of a broadened boundary relaxation.
Abstract: Characterization of the mechanical damping properties of a series of die-cast zinc-aluminum alloys is described. Over the range of variables (temperature, frequency, and vibration strain amplitude) normally encountered in service applications, it is shown that the damping consists of two components. Both components are due to linear relaxation mechanisms: the first is a thermoelastic relaxation and the second is the low-temperature tail of a broadened boundary relaxation. Some of the alloys exhibit elevated damping levels over a useful frequency range, particularly at the temperatures encountered in under-hood applications in automobiles.
TL;DR: In this paper, the Laplace and Hankel transforms are employed to solve the problem of temperature-rate-dependent thermoelasticity in a linear, homogeneous and isotropic unbounded solid.
Abstract: Temperature-rate-dependent thermoelasticity theory is employed to study thermoelastic interactions due to a continuous line source in a linear, homogeneous and isotropic unbounded solid. Laplace and Hankel transforms are employed to solve the problem. Explicit expressions for temperature and stress fields are obtained for small time approximation. Numerical results for a copper material are presented.
TL;DR: In this paper, the influence of material inhomogeneity and anisotropy on the reversible, adiabatic thermoelastic effect in laminated, continuous-fiber composites is investigated analytically and experimentally.
Abstract: The influence of material inhomogeneity and anisotropy on the reversible, adiabatic thermoelastic effect in laminated, continuous-fiber composites is investigated analytically and experimentally. The plane-stress solution for strains in a uniform laminate is combined with a simple micromechanics description of a fiber-reinforced lamina to approximate the nonhomogeneous strains in the fibers and matrix. The equations of anisotropic, linear thermoelasticity are then used to evaluate the temperature change in each of the microconstituents during an adiabatic deformation. The average temperature change of the surface plies of several carbon/epoxy laminates are computed and compared with experimental data obtained via differential infrared thermography. Results indicate that material parameters such as the volume fraction and thermoelastic properties of the microconstituent materials, the orientations of the laminae within the laminate, and the orientation of the lamina on the surface of observation affect the...
TL;DR: In this paper, the authors investigated the longitudinal wave propagation in nonlocal thermoelastic plates using the integral form of constitutive equations, balance of momenta and energy, field equations are obtained.
Journal Article•
01 Jan 1991-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, the shape memory effect was studied in rapidly quenchd melt-spun Ti50Ni50−xCux (x = 0-20 at.%).
Abstract: Abstract Several properties with a thermoelastic phase transformation, the so-called shape memory effect, were studied in rapidly quenchd melt-spun Ti50Ni50−xCux (x = 0–20 at.%). By taking account of the improvements in several characteristics such as the large ductility (i.e. 180° bending ability), narrow transformation temperature range δT( = Af − Mf) and high thermal energy conversion ability ν, it can be concluded that the merit and functional superiority of rapidly quenched melt-spun TiNiCu ribbon exist especially in the range of copper contents over 10 at.% in comparison with the conventionally manufactured (i.e. melting-mechanically worked) material.