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Showing papers on "Thermoelastic damping published in 1994"


Book
01 Jun 1994
TL;DR: In this article, a general hyperbolic model for networks of elastic strings is proposed, and a general model of linear shearable 3-d beams is proposed for string networks.
Abstract: Part 1: general overview on the contents of the book. Part 2 Modelling of networks of elastic strings: modelling of nonlinear elastic strings networks of nonlinear elastic strings linearization wellposedness of the network equations controllability of networks of elastic strings - exact controllability of tree networks, lack of controllability for networks with closed circuits stabilizability of string networks string networks with masses at the nodes. Part 3 Networks of thermoelastic beams modelling of a thin thermoelastic curved beam the equations of motion - some remarks on warping and torsion rotating beams - dynamic stiffening nonlinear nonshearable 3-d beams - approximation-generalizations linear shearable 3-d beams nonlinear shearable 2-d beams - approximation-generalizations a list of beam models - damping networks of beams - geometric joint conditions, rigid joints pinned joints, dynamic joint conditions, rigid joints, pinned joints rotating two-link nonlinear shearable beams. Part 4 A general hyperbolic model for networks: the general model some special cases - string networks, networks of planar Timoshenko beams, networks of linear shearable beams, networks of initially curved bresse beams, beams and strings existence and regularity of solutions energy estimates for hyperbolic systems exact controllability of the network model stabilizability of the network model. Part 5 Spectral analysis and numerical simulation: eigenvalue problems for networks - notation networks of strings setworks of Timoshenko beams Euler-Bernoulli beams the eigenvalue problem for mechanical networks - the string case, homogeneous network of strings, examples, the homogenous Timoshenko network numerical simulations of controlled networks, introductory remarks, absorbing controls, cirecting controls finite element approximations of networks - dry friction at joints. Part 6 Interconnected membranes: modelling of dynamic nonlinear elastic membranes - equations of motion, edge conditions, Hamilton's Principle systems of interconnected elastic membranes - geometric junction conditions, dynamic conditions, linearization, well-posedness of the linear model controllability of linked isotropic membranes - observability estimates for the homogeneous problem, a priori estimates for serially connected membranes, a priori estimates for single jointed membrane systems, the reachable states, serially connected membranes, membrane transmission problems. Part 7 Systems of linked plates: modelling of dynamic nonlinear elastic plates (Part contents)

278 citations


Journal ArticleDOI
TL;DR: In this paper, the authors investigated the viscous energy loss in oscillating fluid-film dampers that provide frictional shear for laterally-driven planar microstructures.
Abstract: Viscous energy loss in oscillating fluid-film dampers that provide frictional shear for laterally-driven planar microstructures is investigated. It is found that Stokes-type fluid motion models viscous damping more accurately than Couette-type flow field. This paper characterizes the damping property of a fluid layer in terms of viscous energy dissipation, then derives analytic damping formulae for practical Q estimation. Theoretical Q-factors are compared to the experimental values, measured from surface-micromachined polysilicon resonators. Data reported by previous investigators are also analyzed and compared. The experimental results indicate that the Stokes-type damping model presents a more general damping treatment with better Q estimation, although discrepancies of 10 to 20% still remain between the estimated and measured Q. >

199 citations


Journal ArticleDOI
TL;DR: In this paper, a model for thermoelastic materials, such as those that display the shape memory and pseudoelastic effect, was examined for a model with an internal variable.
Abstract: A model is examined for thermoelastic materials, such as those that display the shape memory and pseudoelastic effect. As is common with models for these materials, an internal variable is utilized...

179 citations


Journal ArticleDOI
TL;DR: In this article, a stability boundary is established in temperature/speed space, the critical temperature being attributable to temperature-dependence of the brake pad material properties, and the form of the resulting unstable perturbations or eigenfunctions changes depending upon the sliding speed and tem- perature.
Abstract: Thermoelastic instability in an automotive disk brake system is investigated exper­ imentally under drag braking conditions. The onset of instability is clearly identifiable through the observation of nonuniformities in temperature measured using embed­ ded thermocouples. A stability boundary is established in temperature/speed space, the critical temperature being attributable to temperature-dependence of the brake pad material properties. It is also found that the form of the resulting unstable perturbations or eigenfunctions changes depending upon the sliding speed and tem­ perature.

135 citations


Journal ArticleDOI
TL;DR: In this paper, a micromechanics model is presented to predict thermoelastic properties of composites reinforced with plain weave fabrics, where a representative volume element is chosen for analysis and the fiber architecture is described by a few simple functions.
Abstract: A micromechanics model is presented to predict thermoelastic properties of composites reinforced with plain weave fabrics. A representative volume element is chosen for analysis and the fiber architecture is described by a few simple functions. Equations are developed to calculate various phase fractions from geometric parameters that can be measured on a cross section. Effective elastic moduli and effective thermal expansion coefficients are determined under the assumption of uniform strain inside the representative volume element. The resulting model is similar to the classical laminated theory, and hence is easier to use than other models available in the literature. An experimental correlation is provided for a number of Nicalon SiC/CVI SiC and Graphite/CVI SiC composite laminates.

113 citations


Journal ArticleDOI
TL;DR: In this paper, a procedure is described to generate fundamental solutions or Green's functions for time harmonic point forces and sources, where the linearity of the field equations permits the Green's function to be represented as an integral over the surface of a unit sphere, and the integrand is the solution of a one-dimensional impulse response problem.
Abstract: A procedure is described to generate fundamental solutions or Green's functions for time harmonic point forces and sources. The linearity of the field equations permits the Green's function to be represented as an integral over the surface of a unit sphere, where the integrand is the solution of a one-dimensional impulse response problem. The method is demonstrated for the theories of piezoelectricity, thermoelasticity, and poroelasticity. Time domain analogues are discussed and compared with known expressions for anisotropic elasticity.

112 citations


Journal ArticleDOI
TL;DR: In this paper, a boundary element formulation for steady-state thermoelastic crack problems is presented, which does not require domain discretization and allows a single region analysis, and the problems are solved by the dual boundary element method which uses displacement and temperature equations on one crack surface and traction and flux equations on the other crack surface.
Abstract: A boundary element formulation, which does not require domain discretization and allows a single region analysis, is presented for steady-state thermoelastic crack problems. The problems are solved by the dual boundary element method which uses displacement and temperature equations on one crack surface and traction and flux equations on the other crack surface. The domain integrals are transformed to boundary integrals using the Galerkin technique. Stress intensity factors are calculated using the path independent Ĵ-integral. Several numerical problems are solved and the results are compared, where possible, with existing solutions.

99 citations


Journal ArticleDOI
TL;DR: In this paper, the governing equations of flexural vibrations of thin, fluid-saturated poroelastic plates are derived in detail, and the dynamic response of a rectangular, simply supported, POROELastic plate to harmonic load is obtained analytically-numerically and the effects of inertia as well as of porosity and permeability on the response is assessed.
Abstract: The governing equations of flexural vibrations of thin, fluid-saturated poroelastic plates are derived in detail. The plate material obeys Biot's theory of poroelasticity with one degree of porosity, while the plate theory employed is the one due to Kirchhoff. These governing equations are compared with the corresponding ones for thermoelastic plates and a poroelastic-thermoelastic analogy for flexural plate dynamics is established in the frequency domain. The dynamic response of a rectangular, simply supported, poroelastic plate to harmonic load is obtained analytically-numerically and the effects of inertia as well as of porosity and permeability on the response is assessed.

86 citations


Journal ArticleDOI
TL;DR: In this paper, a new physical model has been proposed for the characterization of slide film damping, where two parallel plates are in relative tangential motion and viscous energy dissipation in the fluid between the two plates becomes a representative damping mechanism.
Abstract: Slide film damping occurs when two parallel plates are in relative tangential motion. Viscous energy dissipation in the fluid between the two plates becomes a representative damping mechanism in laterally driven microdevices. In this paper, we investigate the slide film damping both theoretically and experimentally. A new physical model has been proposed for the characterization of slide film damping. Dynamic characteristics of a fluid film have been described in terms of velocity profiles, damping mechanisms, and levels of viscous energy dissipation. Simplified analytical damping formulae have been developed for practical Q estimation. The theoretical Q compares well with the experimental Q. Data reported by previous investigators are also analyzed and compared with the Q value estimated in the present study. It is concluded that our theoretical model offers simple and reasonably good quantitative prediction of Q. Possible sources of error in the theoretical Q prediction are discussed. The effects of fluid-film thickness and microstructure geometry on Q are investigated, so that the results can be used in the damping design for laterally driven microtransducers.

83 citations


Journal ArticleDOI
TL;DR: The behavior of initially orthogonal damping during inelastic response is examined in this article, where it is shown that in systems with massless coordinates, or where a subset of the total number of degrees-of-freedom (DOF) is associated with small inertias, loss of damping orthogonality can lead to the generation of spurious damping forces.
Abstract: The behavior of initially orthogonal damping during inelastic response is examined. It is shown that in systems with massless coordinates, or where a subset of the total number of degrees-of-freedom (DOF) is associated with small inertias, loss of damping orthogonality can lead to the generation of spurious damping forces. Analytical inspection illustrates that these forces depend on the form of the damping matrix and on the changes in the statical relationship between primary and secondary DOF introudced by yielding. Numerical results are obtained to validate the analytical observations and to examine the quantitative significance of the spurious forces on the computed response. It is shown that in systems with massless coordinates the potential for spurious behavior is obviated when the damping matrix is assembled restricting the exponents of the Caughey series to zero or negative. The foregoing constrain, which is equivalent to requiring that massless coordinates be condensed from the stiffness prior to assembly of the damping, is shown to be necessary for the damping matrix to be unique for a given set of modal damping ratios.

80 citations


Journal ArticleDOI
TL;DR: In this paper, a two-dimensional problem of a thick plate whose lower and upper surfaces are traction free and subjected to a given axisymmetric temperature distribution is considered within the context of the theory of generalized thermoelasticity with one relaxation time.
Abstract: The two-dimensional problem of a thick plate whose lower and upper surfaces are traction free and subjected to a given axisymmetric temperature distribution is considered within the context of the theory of generalized thermoelasticity with one relaxation time. Potential functions together with Laplace and Hankel transform techniques are used to derive the solution in the transformed domain. The Hankel transforms are inverted analytically. The inversion of the Laplace transforms are carried out using the inversion formula of the transform together with Fourier expansion techniques. Numerical methods are used to accelerate the convergence of the resulting series and to evaluate the improper integrals involved to obtain the temperature and stress distributions in the physical domain. Analysis of wave propagation in the medium is presented. Numerical results are represented graphically and discussed. A comparison is made with the solution of the corresponding coupled problem.

Journal ArticleDOI
TL;DR: In this paper, an analysis of laser-induced waves propagating in an absorbing thermoelastic semi-space of the Green-Lindsay type is presented, where a volume model of absorption in which a laserinduced heat has the form of a product of an exponentially decreasing function of the semi space depth and a skewed Gaussian temporal profile is assumed.
Abstract: An analysis of laser-induced waves propagating in an absorbing thermoelastic semi-space of the Green-Lindsay type is presented. A volume model of absorption in which a laser-induced heat has the form of a product of an exponentially decreasing function of the semi-space depth and a “skewed” Gaussian temporal profile is assumed. A closed-form solution to the associated one-dimensional initial-boundary value problem is obtained. A qualitative analysis of the solution shows that for a fixed cross-section of the semi-space the stress-temperature response of the body is represented by a pair of smooth transiental functions of time.

Journal ArticleDOI
TL;DR: In this paper, a finite element package has been written to use this model to calculate the effective thermal expansion coefficient of the polycrystalline aggregate using the single crystal thermoelastic properties.
Abstract: The three-dimensional Poisson-Voronoi model is used to simulate a topologically equivalent material microstructure. A finite element package has been written to use this model to calculate the effective thermal expansion coefficient of the polycrystalline aggregate using the single crystal thermoelastic properties. The results have been found to be close to the experimental values and the values calculated from the Hashin's exact equation for hexagonal, tetragonal and trigonal materials.

Journal ArticleDOI
TL;DR: In this article, the second law of thermodynamics is used as a starting point for calculating the temperature damping from the entropy produced by tensile tensile stress, and a general theory is developed to calculate the damping.
Abstract: In accordance with the Thomson effect (Thomson, 1853), when a thermoelastic solid is subjected to a tensile stress, it cools. Similarly, when a homogeneous material is subjected to an inhomogeneous stress field or when an heterogeneous material is subjected to any stress field (homogeneous or inhomogeneous), different parts of the material undergo different temperature changes. As a result irreversible heat conduction occurs and entropy is produced. In this paper we take the second law of thermodynamics as our starting point and develop a general theory for calculating the thermoelastic damping from the entropy produced.

Journal ArticleDOI
TL;DR: In this paper, the authors developed a crack growth analysis using a single region boundary element formulation which does not require any remeshing as the crack grows and is well suited to crack growth problems because of the boundary only discretization.
Abstract: The fundamental postulate of linear-elastic fracture mechanics is that crack behavior is determined solely by the value of the stress intensity factors The calculation of stress intensity factors usually requires numerical methods because of the complex geometries and because the geometry changes as the crack grows The boundary element method [1] is well suited to crack growth problems because of the boundary only discretization, compared to the domain discretization needed for the finite element method Portela, Alibadi and Rooke [2] developed a crack growth analysis using a single region boundary element formulation which does not require any remeshing as the crack grows

Journal ArticleDOI
TL;DR: In this paper, the authors presented a numerical model that calculates the surface displacements generated by the absorption of a laser pulse by an orthotropic medium using temporal Laplace and spatial two-dimensional Fourier transformations.
Abstract: We present a numerical model that calculates the surface displacements generated by the absorption of a laser pulse by an orthotropic medium. This model solves the heat and acoustic wave equations using temporal Laplace and spatial two-dimensional Fourier transformations. This model allows us to calculate the normal and in-plane displacements on the front or back surface of an orthotropic plate over a complete area and for virtually any time and beam profiles of the laser excitation. Numerical simulations are compared to experimental results obtained on an aluminum sample and on a graphite-eppxy plate. The experimental and numerical results are in good agreement. Laser generation of ultrasound, especially when coupled to optical detection, has been recognized to be a powerful tool for nondestructive materials evaluation.'-3 In the thermoelastic generation regime, a localized temperature elevation in the sample induced by the absorption of a laser pulse results in a localized thermal expansion which, in turn, generates ultrasonic waves. Several approaches were proposed for modeling this thermoelastic process, essentially using Green functions4-7 or Laplace and Hankel transformations.8'9 However, the use of Green functions or Hankel transformations for modeling this process cannot be easily extended to the case of anisotropic materials such as materials with an orthotropic symmetry. Other numerical techniques, like the finite element technique, " are not suitable for the resolution of the laser generation of ultrasound. In this letter, we present a model based on temporal Laplace and spatial two-dimensional (2D) Fourier transformations that allows us to describe the thermoelastic generation of ultrasound in the case of an orthotropic sample. In our model, we consider an infinite plate of finite thickness L made of an orthotropic material. The coordinate =es XI, x2, and x3 correspond to the principal axes of the medium, with x3 being the optical axis of the incident laser radiation. The stiffness tensor [C] of the orthotropic medium has then only nine different nonzero components when the abbreviated notation is used.'r To describe the laser generation of ultrasound in the ther-moelastic regime, one must solve simultaneously the heat equation and the acoustic wave equation. In our model, we neglect the mechanical heat sources in the heat equation. This assumption is valid for the time scales of our simulations.7~gP12 We use the hyperbolic heat equation' even if in the cases studied, the classical one would be adequate. The temperature elevation field 6 is then given by d6 Bs v([k]w)=pc, at +7x-%dxlkk-l " 3f(t>, i 1 (1)

Journal ArticleDOI
TL;DR: In this paper, the authors consider the incorporation of thermal effects into the continuum modeling of dynamic solid-solid phase transitions and present an initial-value problem that gives rise to both shock waves and a propagating phase boundary.
Abstract: This paper is concerned with the incorporation of thermal effects into the continuum modeling of dynamic solid-solid phase transitions. The medium is modeled as a one-dimensional thermoelastic solid characterized by a specific Helmholtz free-energy potential and a specific kinetic relation. Heat conduction and inertia are taken into account. An initial-value problem that gives rise to both shock waves and a propagating phase boundary is analyzed on the basis of this model.

Journal ArticleDOI
TL;DR: In this article, a new stress vector function (the hexagonal stress vector ) is introduced to obtain, in closed form, the elastic fields due to an inclusion in transversely isotropic solids.
Abstract: A method that introduces a new stress vector function ( the hexagonal stress vector ) is applied to obtain, in closed form, the elastic fields due to an inclusion in transversely isotropic solids. The solution is an extension of Eshelby’s solution for an ellipsoidal inclusion in isotropic solids. The Green’s functions for double forces and double forces with moment are derived and these are then used to solve the inclusion problem. The elastic field inside the inclusion is expressed in terms of the newtonian and biharmonic potential functions, which are similar to those needed for the solution in isotropic solids. Two more harmonic potential functions are introduced to express the solution outside the inclusion. The constrained strain inside the inclusion is uniform and the relation between the constrained strain and the misfit strain has the same characteristics as those of the Eshelby tensor for isotropic solids, namely, the coefficients coupling an extension to a shear or one shear to another are zero. The explicit closed form expression of this tensor is given. The inhomogeneity problem is then solved by using Eshelby’s equivalent inclusion method. The solution for the thermoelastic displacements due to thermal inhomogeneities is also presented.

Journal ArticleDOI
TL;DR: In this paper, a method for predicting the damped dynamic characteristics of thick composite laminates and plates is presented, which relates the damping of composite plates to constituent properties, fiber volume ratio, fiber orientation, laminate configuration, plate geometry, temperature, and moisture.
Abstract: A method for predicting the damped dynamic characteristics of thick composite laminates and plates is presented. Unified damping mechanics relate the damping of composite plates to constituent properties, fiber volume ratio, fiber orientation, laminate configuration, plate geometry, temperature, and moisture. Discrete layer damping mechanics for thick laminates, entailing piecewise continuous displacement fields and including the effects of interlaminar shear damping, are described. A semi-analytical method for predicting the modal damping and natural frequencies of thick simply-supported specialty composite plates is included. Applications demonstrate the validity, merit, and ranges of applicability of the new theory. The applications further illustrate the significance of interlaminar shear damping, and investigate the effects of lamination, thickness aspect ratio, fiber content, and temperature.

Journal ArticleDOI
TL;DR: Using the theory of elasticity, analytical expressions have been derived for the thermoelastic stresses and deformations in an axially symmetric three-dimensional solid body caused by the absorption of laser light, revealing many important qualitative features including the spatial location of the peak stresses, which is more consistent with experimental observations of failure.
Abstract: Under certain conditions, laser light incident on a target material can induce an explosive removal of some material, a process called laser ablation. The photomechanical model of laser ablation asserts that this process is initiated when the laser-induced stresses exceed the strength of the material in question. Although one-dimensional calculations have shown that short pulsed lasers can create significant transient tensile stresses in target materials, the stresses last for only a few nanoseconds and the spatial location of the peak stresses is not consistent with experimental observations of material failure in biological tissues. Using the theory of elasticity, analytical expressions have been derived for the thermoelastic stresses and deformations in an axially symmetric three-dimensional solid body caused by the absorption of laser light. The full three-dimensional solution includes three stresses, radial, circumferential and shear, which are necessarily absent in the simple one-dimensional solution. These stresses have long-lived components that exist for eight orders of magnitude longer in time than the acoustic transients, an important point when the details of dynamic fracture are considered. Many important qualitative features are revealed including the spatial location of the peak stresses, which is more consistent with experimental observations of failure.

Journal ArticleDOI
TL;DR: In this paper, an initial value problem of Riemann type, based on momentum balance, energy balance, kinematic compatibility and the entropy inequality, has a one-parameter family of solutions for a range of given data.

Journal ArticleDOI
TL;DR: It is shown that, unlike the one-dimensional thermoelastic model of laser-induced stress generation that has appeared in the literature, the full three-dimensional solution predicts the development of significant tensile stresses on the surface of the target, precisely where ablation is observed to occur.
Abstract: The photomechanical model of laser ablation of biological tissue asserts that ablation is initiated when the laser-induced tensile stress exceeds the ultimate tensile strength of the target. We show that, unlike the one-dimensional thermoelastic model of laser-induced stress generation that has appeared in the literature, the full three-dimensional solution predicts the development of significant tensile stresses on the surface of the target, precisely where ablation is observed to occur. An interferometric technique has been developed to measure the time-dependent thermoelastic expansion, and the results for subthreshold laser fluences are in precise agreement with the predictions of the three-dimensional model.

Journal ArticleDOI
TL;DR: In this paper, the authors studied the properties of shape memory alloys as a function of manganese concentration and heat treatment and found that the loss of pseudoelastic properties was due to dislocation accumulation at their interfaces.
Abstract: The thermoelastic and mechanical properties of CuAlNiBMn shape memory alloys have been studied as a function of manganese concentration and of heat treatment. Below a limiting value of manganese content, the loss of thermoelastic and pseudoelastic properties has been observed, in particular in the quenched specimens. The partial transformation and its degradation during thermal cycling observed in the low manganese content alloy has been attributed to the lower degree of B2 order achieved during the quench, leading to slower kinetics of DO 3 ordering. The accomodation of strains between martensite variants and between the martensite/austenite phases appear to need dislocation accumulation at their interfaces. The presence of dislocations observed during the reverse transformation seem responsible for the degradation of the transformation and the loss of pseudoelastic properties of this alloy.

Journal ArticleDOI
TL;DR: In this paper, a successive approximation method was proposed and applied in connection with static and dynamic analyses of homogeneous isotropic, orthotropic and cross-ply laminated hollow cylinders and cylindrical panels.

Journal ArticleDOI
TL;DR: In this article, the theoretical analysis of a three-dimensional transient thermal stress problem is developed for a nonhomogeneous hollow sphere with respect to rotating heat source from the outer surface.
Abstract: In this study, the theoretical analysis of a three-dimensional transient thermal stress problem is developed for a nonhomogeneous hollow sphere with respect to rotating heat source from the outer surface. We assume that the hollow sphere has nonhomogeneous thermal and mechanical material propeties is the radial direction. The heat conduction problem and the associated thermoelastic behavior for such nonhomogeneous media are developed by introducing the theory of laminated composites as one theoretical approximation. The transient heat conduction problem is evaluated with the aid of the method of Laplace transformation. The associated thermoelastic field is analyzed by making use of the thermoelastic displacement potential and the complementary harmonic function. Some numerical results for the temperature change and the stress distributions are shown in figures.

Journal ArticleDOI
TL;DR: In this paper, the analytical theory of thermal stresses is constructed under some natural simplifying assumptions, such as that of the thermoelastic or thermo-elastic-plastic behavior of the materials of a film and substrate after depositing the film and cooling the composite system to an operational temperature.
Abstract: It is generally recognized that thermal stresses in thin films are primarily responsible for morphological changes in thin films, including hillocks, whiskers, and void or pit formations, which present serious problems of reliability in microelectronics. In the present paper, the analytical theory of thermal stresses is constructed under some natural simplifying assumptions. The latter include that of the thermoelastic or thermoelastic‐plastic behavior of the materials of a film and substrate after depositing the film and cooling the composite system to an operational temperature. The closed system of governing partial differential equations for thermal stresses in a thin film is derived for any in‐plane shape of the film. Some particular problems are solved in an explicit form and the implication of the solutions for the prediction of hillocks is discussed. Numerical and physical experiments are planned to verify the theory.

Journal ArticleDOI
TL;DR: In this paper, boundary control of a linear partial differential equation that describes the temperature distribution and displacement within a one-dimensional thermoelastic rod is examined, and it is shown that temperature or heat flux control at an endpoint is sufficient to obtain exact null-controllability.
Abstract: Boundary control of a linear partial differential equation that describes the temperature distribution and displacement within a one-dimensional thermoelastic rod is examined. In particular, it is shown that temperature or heat flux control at an endpoint is sufficient to obtain exact null-controllability. This improves earlier results for similar systems in which only partial null-controllability is obtained. Sharp regularity results for the controlled system are also obtained.

Journal ArticleDOI
TL;DR: In this paper, a rotating disk with varying thickness and inhomogeneity, and subjected to a steady, inhomogeneous temperature field is analyzed, and the disk is discretized into a series of uniform annular disks possessing constant material properties and then solved by the step reduction method.
Abstract: A rotating disk with varying thickness and inhomogeneity, and subjected to a steady, inhomogeneous temperature field is analyzed. To handle the arbitrary profile, the disk is discretized into a series of uniform annular disks possessing constant material properties and then solved by the step reduction method. Analytic expressions for thermoelastic stresses are given, and based on these results, the formulation is extended to include the calculation of shrink fit, the solving of the inverse problem for equistrength rotating disks, and the computations of plastic stresses and creep at elevated temperatures

Journal ArticleDOI
TL;DR: In this article, the influence of heat treatment on the elastic and nonelastic parameters of internal friction of high-chromium ferritic alloys and α-Fe has been examined.
Abstract: The influence of heat treatment on the elastic and nonelastic parameters of internal friction of high-chromium ferritic alloys and α-Fe has been examined. Mechanisms of the formation of magnetoelastic and dislocation hysteresis have been investigated. Temperature ranges and temperature and amplitude critical points connected with different damping mechanisms have been established. Heat treatment for maximum damping capacity has been suggested, and the results of damping capacity of about 50 steels were generalized.

Book ChapterDOI
TL;DR: In this article, the authors focus on the micromechanical description of transformation plasticity, incorporating microstructure, crystallography, thermodynamics, and micromachanics into the continuum formulation of the macroscopic constitutive behavior, and illustrate that it is possible to describe and interpret various phenomena by a unified interrelated micromchanics model, and when this is done, the description of rather complex phenomena involved in complex thermomechanical loading paths can be obtained.
Abstract: Publisher Summary This chapter is primarily concerned with the micromechanical description of transformation plasticity, incorporating microstructure, crystallography, thermodynamics, and micromechanics into the continuum formulation of the macroscopic constitutive behavior. The chapter attempts to illustrate that it is possible to describe and to interpret various phenomena by a unified interrelated micromechanics model, and it is shown that when this is done, the description of rather complex phenomena involved in complex thermomechanical loading paths can be obtained. Examples of such analyses are taken from recent studies of deformation of polycrystalline shape memory alloys and zirconian ceramics. Section II of the chapter gives a brief review of the previous research activities and recent development in this area. The general characteristics of the thermoelastic martensitic transformations and the most important deformation mechanisms are outlined. In Section III, the analytical expression of the Gibbs free energy of the material is derived based primarily upon the energy changes during the deformation process. In Section IV, the constitutive laws for the forward and reverse transformations, and reorientation processes in any thermomechanical loading histories are derived through energy balance analysis. In Section V, the individual phenomena of the phase transforming materials are studied and discussed in detail with the present constitutive theory.