Thermoelasticity theory

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Magneto viscoelastic plane waves in rotating media in the
generalized thermoelasticity II

Magneto viscoelastic plane waves in rotating media in the generalized thermoelasticity II

It seems relevant from the above discussion that little attention has been given to the study of propagation of thermoelastic plane waves in a rotating medium in presence of an external magnetic field based on the generalized thermoelasticity. In view of the fact that most large bodies like the earth, the moon, and other planets have an angular veloc- ity, it is important to consider the propagation of magneto-thermoelastic plane waves in an electrically conducting, rotating viscoelastic medium under the action of an external magnetic field. In this connection, Choudhuri and Debnath [9, 10, 11, 12, 13] have stud- ied propagation of magneto-thermoelastic plane waves in rotating thermoelastic media permeated by a primary uniform magnetic field using the generalized heat conduction equation of Lord and Shulman. In the present problem, we have studied the propagation of time-harmonic coupled electromagneto-viscoelastic dilatational thermal shear waves using the thermoelasticity theory of type II [14, Green-Naghdi model]. This thermoe- lastic model possesses several significant characteristics that di ff er from the traditional classical development in thermoelastic material behaviors: (i) it does not involve thermal energy dissipation, (ii) the entropy flux vector (or equivalently, the heat-flow vector) in the theory is determined in terms of the same potential that also determines the stresses, (iii) it permits transmission of heat flow as thermal waves at finite speed. Several problems in thermoelasticity of type II (without thermal energy dissipation) have been studied by several authors [4, 5, 6, 7, 8, 23]. In this paper, GN model of thermoelasticity of type II is used to obtain a more general dispersion equation to ascertain the effects of rotation, finite thermal waves speed c T of GN theory, thermoelastic coupling constant and the

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A Problem in Different Theories of Magneto- Thermoelasticity in Cylindrical Region with Laser Pulse

A Problem in Different Theories of Magneto- Thermoelasticity in Cylindrical Region with Laser Pulse

Green and Nagdhi [18-20] have formulated a new model of thermoelasticity. This model predicts that the internal rate of production of entropy is identically zero, i.e., there is no dissipation of thermal energy. This theory (GN theory) is known as thermoelasticity without energy dissipation theory. In the development of this theory the thermal displacement gradient is considered as a constitutive variable, whereas in the conventional development of a thermoelasticity theory, the temperature gradient is taken as a constitutive variable [12]. A couple of uniqueness theorems have been proved in [21-22], and one-dimensional waves in a half-space and in an unbounded body have been studied in [23-25].

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Magnetoelastic plane waves in rotating media in thermoelasticity of type II (G N model)

Magnetoelastic plane waves in rotating media in thermoelasticity of type II (G N model)

It seems relevant from the above discussion that little attention has been given to the study of propagation of thermoelastic plane waves in a rotating medium in the presence of external magnetic field based on the generalized thermoelasticity. In view of the fact that most large bodies, like the earth, the moon, and other planets, have an angular ve- locity, it is important to consider the propagation of magnetothermoelastic plane waves in an electrically conducting, rotating elastic medium under the action of the external magnetic field with or without thermal relaxation. In this connection, Roychoudhuri and Debnath [17, 18, 19, 21, 20] have studied propagation of magnetothermoelastic plane waves in a rotating thermoelastic medium permeated by a primary uniform magnetic field by using the generalized heat conduction equation of Lord and Shulman. In the present problem, we have studied the propagation of time-harmonic coupled electro- magnetoelastic dilatational thermal shear waves using the thermoelasticity theory of type II [9] (Green-Naghdi (G-N) model 1993). This thermoelastic model possesses several significant characteristics that differ from the traditional classical development in ther- moelastic material behaviors: (i) it does not sustain energy dissipation, (ii) the entropy flux vector (or equivalently heat flow vector) in the theory is determined in terms of the same potential that also determines the stress, (iii) it permits transmission of heat flow as thermal waves at finite speed. Several problems in thermoelasticity relating to this Green-Naghdi theory of thermoelasticity of type II (without thermal energy dissipation) have been studied by several authors [4, 5, 6, 7, 8, 23]. In this paper, G-N model of thermoelasticity of type II is used to obtain a more general dispersion equation to as- certain the effects of rotation, thermal parameter c T , the nondimensional thermal wave

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Generalized Thermoelasticity Problem of Material Subjected to Thermal Loading Due to Laser Pulse

Generalized Thermoelasticity Problem of Material Subjected to Thermal Loading Due to Laser Pulse

The absence of any elasticity term in the heat conduc- tion equation for uncoupled thermoelasticity appears to be unrealistic, since due to the mechanical loading of an elastic body, the strain so produced causes variation in the temperature field. Moreover, the parabolic type of the heat conduction equation results in an infinite velocity of thermal wave propagation, which also contradicts the actual physical phenomena. Introducing the strain-rate term in the uncoupled heat conduction equation, Biot extended the analysis to incorporate coupled thermoelas- ticity [1]. In this way, although the first shortcoming was over, there remained the parabolic type partial differen- tial equation of heat conduction, which leads to the pa- radox of infinite velocity of the thermal wave. To elimi- nate this paradox generalized thermoelasticity theory was developed subsequently. Due to the advance-

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Non Classical Thermoelasticity in a Half Space under the influence of a Heat Source

Non Classical Thermoelasticity in a Half Space under the influence of a Heat Source

Thermoelastic problems are used to study the thermal stresses in an elastic body under high temperature gradients. The problems of thermoelasticity are broadly classified into two categories, namely static and dynamic problems. The problems dealing with dynamic thermal stresses are fundamentally important in engineering processes and have paved the way for technologies which operate in high temperatures such as nuclear reactors, aerodynamic structures, etc. The classical coupled thermoelasticity theory finds its first mention in Biot [1]. In non-classical theories of thermoelasticity, the Fourier heat conduction equation is generalized with the introduction of one relaxation time obtained by Lord and Shulman [2]. Various authors [3-8] contributed to the problems on generalized thermoelasticity. Recently, a lot of interest has developed in fractional order theory of thermoelasticity [9-15].

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The Effect of Magnetic Field on an Infinite Conducting Thermoelastic Rotating Medium under G-N theory

The Effect of Magnetic Field on an Infinite Conducting Thermoelastic Rotating Medium under G-N theory

Green and Naghdi (G-N) have formulated three models (I, II, III) of thermoelasticity for homogeneous and an isotropic materials [1, 2]. Model I of G-N theory after linearization reduced to the classical thermoelasticity theory. Model II of G-N theory [3] does not suction dissipation of the thermoelastic energy. In this model, the constitutive equations are derived by starting with the reduced energy equation and by including the thermal displacement gradient among the constitutive variables. Chandrasekharaiah [4] used Laplace method to study the one-dimensional thermal wave propagation in a half space based on G-N theory of type II due to a sudden application of the temperature to the boundary. The disturbances produced in a half space by the application of a mechanical point load and thermal source acting on a boundary of the half space is investigated in ref. [5]. Model III of G-N theory confesses a dissipation of energy, where the constitutive equations are derived starting with a reduced energy equation. It includes the thermal displacement gradient, in addition to the temperature gradient among its independent constitutive variables.

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Thermoelastic waves without energy dissipation in an unbounded body with a spherical cavity

Thermoelastic waves without energy dissipation in an unbounded body with a spherical cavity

1. Introduction. Thermoelasticity theories that admit finite speeds for thermal sig- nals have aroused much interest in the last three decades. In contrast to the conven- tional coupled thermoelasticity theory based on a parabolic heat equation [1], which predicts an infinite speed for the propagation of heat, these theories involve hyper- bolic heat equations and are referred to as generalized thermoelasticity theories. For details about the physical relevance of these theories and a review of the relevant literature, see [2].

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Effect of Laser Heat Source on One Dimensional Generalized Thermoelasticity

Effect of Laser Heat Source on One Dimensional Generalized Thermoelasticity

The absence of any elasticity term in the heat conduction equation for uncoupled thermoelasticity appears to be unrealistic, since due to the mechanical loading of an elastic body, the strain so produced causes variation in the temperature field. Moreover, the parabolic type of the heat conduction equation results in an infinite velocity of thermal wave propagation, which also contradicts the actual physical phenomena. Introducing the strain-rate term in the uncoupled heat conduction equation, Biot extended the analysis to incorporate coupled thermoelasticity [1]. In this way, although the first shortcoming was over, there remained the parabolic type partial differential equation of heat conduction, which leads to the paradox of infinite velocity of the thermal wave. To overcome this paradox, generalized thermoelasticity theory was developed subsequently. Due to the advancement of pulsed lasers, fast burst nuclear reactors and particle accelerators, etc. which can supply heat pulses with a very fast time-rise [2,3], generalized thermoelasticity theory is receiving serious attention. The development of the second sound effect has been nicely reviewed by Chandrasekharaiah [4]. At present, mainly two different models of generalized thermoelasticity are being extensively used- one proposed by Lord and Shulman [5] and the other proposed by Green and Lindsay [6]. LS (Lord and Shulman) theory introduces one relaxation time and according to this theory, only Fourier’s heat conduction equation is modified. While GL (Green and Lindsay) theory introduces two relaxation times and both the energy equation and the equation of motion are modified.

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GENERALIZED MAGNETO- THERMOELASTICITY AND HEAT CONDUCTION ON AN INFINITE MEDIUM WITH SPHERICAL CAVITY

GENERALIZED MAGNETO- THERMOELASTICITY AND HEAT CONDUCTION ON AN INFINITE MEDIUM WITH SPHERICAL CAVITY

The theory of Thermo elasticity deals with the effect of mechanical and thermal disturbances on an elastic body. In the nineteenth century, Duhamel (1837) was the first to consider elastic problems with heat changes. In 1855 Neumann (1841) re derived the equations obtained by Duhamel using a different approach. Their theory, the theory of uncoupled thermo elasticity consists of the heat equation which is independent of mechanical effects and the equation of motion which contains the temperature as a known function. There are two defects of the theory. First, the fact that the mechanical state of the elastic body has no effect on the temperature. This is not in accord with true physical experiments. Second, the heat equation being parabolic, predicts an infinite speed of propagation for the temperature which again contradicts physical observations.

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Well-Posedness and Asymptotic Stability to a Laminated Beam in Thermoelasticity of Type III

Well-Posedness and Asymptotic Stability to a Laminated Beam in Thermoelasticity of Type III

Motivated by the above results, in the present work, we study the well-posedness and asymp- totic behaviour of solutions to the laminated beam (1.1) in thermoelasticity of type III. By using semigroup method and Lumer-Philips theorem, we prove the existence and uniqueness of the solution. By using the perturbed energy method and construct some Lyapunov functionals, we then obtain the exponential decay result for the case of equal wave speeds, i.e., ρ G

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Thermoelastic symmetric and antisymmetric wave modes with trigonometric functions in laminated plates

Thermoelastic symmetric and antisymmetric wave modes with trigonometric functions in laminated plates

The Classical Fourier law of heat conduction and conse- quent mathematical models for temperature dynamics constructed on the basis of parabolic partial differential equations assumes that the thermal disturbances propa- gate at infinite speeds. However, the assumption may lead to an inaccurate response of the super large-scale space structures, since a time lag of the propagation of the thermal disturbances in such structures could not be dis- regarded. The literature dedicated to coupled and general- ized theories of thermoelasticity theories is quite large and its detailed review can be found in Nowacki (1975, 1986), Chadwick (1960, 1979), and Chadwick and Seet (1970).

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Eigenvalue Approach to Thermoelastic Interactions in an Unbounded Body with a Spherical Cavity

Eigenvalue Approach to Thermoelastic Interactions in an Unbounded Body with a Spherical Cavity

Specific heat at constant strain. t = Time variable. K = Coefficient of thermal conductivity. γ = (3 λ + 2 μ ) β ∗ . β ∗ = Coefficient of volume expansion. β = Coefficient of stress temperature. k ∗ = Material constants characteris- tic of the theory. H ( t ) = Heaviside unit step function.

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A context based elderly care theory: a grounded theory approach

A context based elderly care theory: a grounded theory approach

Caring is the essence of nursing which is highly applicable to any type of clients. However, the concept of caring explored in the study focused on the elderly care and how this is tion of cultural differences and backgrounds. Objective: This study developed a substantive theory on elderly care known as the Elderly Care Theory that defined what and how elderly caring is based on Filipino context of caring. Methods: This was using grounded theory with ten care providers interviewed and an actual observation of the The theoretical assumptions developed were: (1) ocess and care agent which ultimately leads to the development of the elderly care satisfaction and quality of life; (2) Caring elements for the elderly are dependent on the quality/extent/status of delivery of caring culture, caring process and the psychological-spiritual and political factors; (3) The care culture has its own elements which interact interdependently with each other fect enhances the flourishing culture in an elderly facility; and (4) The care process and agents have interactive elements such as confident, enduring and strategic care and its combined effect creates the caring self. Conclusion: The care for is a holistic and specialized care. The elderly care elements necessary for the provision of cultural, and spiritual factors of care and the personal

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Quasi Static Problem of Thermoelasticity for Thermosensitive Infinite Circular Cylinder of Complex Heat Exchange

Quasi Static Problem of Thermoelasticity for Thermosensitive Infinite Circular Cylinder of Complex Heat Exchange

Nonlinear nonstationary heat conduction problem for infinite circular cylinder under a complex heat transfer taking into account the temperature dependence of thermophysical characteristics of materials is solved numerically by the method of lines. Directing it to the Cauchy’s problem for systems of ordinary differential equations studied feature which takes place on the cylinder axis. Taken into account the dependence on the temperature coefficient of heat transfer that the different interpretation of its physical content makes it possible to consider both convective and convective-ray or heat ray. Using the perturbation method, the corresponding thermoelasticity problem taking into account the temperature dependence of mechanical properties of the material is construed. The influence of the temperature dependence of the material on the distribution of temperature field and thermoelastic state of infinite circular cylinder made of titanium alloy Ti-6Al-4V by radiant heat transfer through the outer surface has been analyzed.

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Magneto thermoelastic waves in a perfectly conducting elastic half space in thermoelasticity III

Magneto thermoelastic waves in a perfectly conducting elastic half space in thermoelasticity III

is a material constant characteristic of the theory. It may be noted that the third model represented by (2.5) of Green and Naghdi [5] for heat transport in solids accommodates infinite thermal wave speed due to the presence of third-order mixed derivative term present on the right-hand side of (2.5) and it involves thermal damping. As such, the corresponding thermoelastic model admits coupled damped thermoelastic waves.

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Transient response of multilayered hollow cylinder  using various theories of generalized thermoelasticity

Transient response of multilayered hollow cylinder using various theories of generalized thermoelasticity

perature is slightly changed and the differences between C-D, L-S, and G-L are very small (tiny). The coupled theory (C-D) may give results with small relative error compared with those given by Lord and Shulman’s (L-S) and Green and Lindsay’s (G-L) theories. However, the results of L-S and G-L are much closed to each other (see Figure 3). 2) The plots of results given by Lord and Shulman’s

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Two Temperature Generalized  Thermoelasticity without Energy  Dissipation of Infinite Medium with  Spherical Cavity Thermally Excited by  Time Exponentially Decaying Laser Pulse

Two Temperature Generalized Thermoelasticity without Energy Dissipation of Infinite Medium with Spherical Cavity Thermally Excited by Time Exponentially Decaying Laser Pulse

Among the authors who contribute to developing this theory, Quintanilla studied existence, structural stability, convergence and spatial behavior for this theory [6], Youssef constructed the generalized Fourier’s law to the two-temperature theory of thermoelasticity and proved its uniqueness of solution for homogeneous isotropic material [7]. Puri and Jordan studied the propagation of plane harmonicwaves, recently [8], Magaña and Quintanilla [9] have studied the uniqueness and growth solutions for the model proposed by Youssef [7]. A new theory of generalized thermoelasticity has been constructed based on two-temperature generalized thermo- elasticity theory for anisotropic and homogeneous body without energy dissipation by Youssef [10]. This new theorem has been constructed in the context of Green and Naghdi model of type II of linear thermoelasticity. Also, a theorem of general uniqueness is proved for two-temperature generalized thermoelasticity without energy dissipation [10].

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Thermoelastic Thick Plate under Illumination of a Uniform Laser Beam with one Relaxation time

Thermoelastic Thick Plate under Illumination of a Uniform Laser Beam with one Relaxation time

A large amount of work has been devoted for solving thermoelasticity problems with the consideration of the coupling effect between temperature and strain rate. Stress waves in a half-space induced by variations of surface strain, temperature, or stress were studied by [Boley and Tolins, 1962] and [Chandrasekhariaiah and Srinath, 1979]. [Mozina and Dovc, 1994] attempted to use the Laplace transform to solve the thermoelastic stress wave induced by volumetric heating. Due to the difficulty in finding analytical Green`s functions, only solution for locations on the surface was obtained .

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Some remarks on growth and uniqueness in thermoelasticity

Some remarks on growth and uniqueness in thermoelasticity

2. Thermoelasticity of type III: uniqueness. The aim of this section is to obtain a uniqueness result for the solutions of system (1.6) and (1.7). From now on, we assume that the functions ρ and c are greater than or equal to a positive constant and that the following inequality

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One Dimensional State Space Approach to Thermoelastic Interactions with Viscosity

One Dimensional State Space Approach to Thermoelastic Interactions with Viscosity

mathematical model of fractional heat conduction law in which the generalized Fouriers law of heat conduction is modified by using the new Taylors series expansion of time fractional order developed by Jumarie [6]. Recently, Youssef [7] derived a new theory of thermoelasticity with fractional order strain which is considered as a new modification to Duhamel- Neumanns stress-strain relation. In this paper, the author postulated a new unified system of equations that govern seven different models of thermoelasticity in the context of one-temperature and two-temperature and one dimensional problem for an isotropic and homogeneous elastic half-space.

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