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In this paper we approach the linear mixed problem with initial and boundary values for a Cosserat body which is elastic and has pores. We coupled the equations characterizing the pores evolution with basic equations that describing the elastic deformations of the Cosserat body. The coupling is done by means of predetermined coefficients. To prove the continuous dependence of the solutions, we introduce an adequate measure which is useful in obtaining of some estimations with respect to the gradient of elastic deformations and regarding the gradient of a specific the application, introduced to characterize the behavior of the pores. [ABSTRACT FROM AUTHOR]

The investigation of the reflection issue in a hygrothermal medium in nonlocal elasticity is the focus of the current research project. The velocity equation is created by formulating and solving the governing equations of a hygro-thermoelastic material. The solution for plane waves predicts three incorporated plane waves, including longitudinal displacement, P-wave, thermal diffusion TD-wave and moisture diffusion mD-wave and shear vertical SV wave propagate in the medium. The velocity of P, TD, mD and SV waves are computed for the hygrothermal medium. Expressions for the energy ratio and reflection coefficient are developed for the incidence of a hygrothermal plane wave. The effect of hygrothermal parameters and nonlocal parameter on velocity, the reflection coefficient and energy ratio are displayed on a graph. [ABSTRACT FROM AUTHOR]

In this paper, we extend some results involving the energy release rate in the case of the propagation of a straight crack in an elastic solid. These results, approached by Gurtin and Yatomi in classical elasticity, are generalized in order to cover a Cosserat-type elastic body. We also investigate the effects of the microinertia and the couple stresses on the energy release rate.

In our study we analyse the vibration of a right cylinder which consists of an elastic material with dipolar structure and has pores. One end of this cylinder is subjected to an excitation, harmonically in time. The other end of the cylinder and its lateral surface are free of loads. We prove that the presence of the voids does not affect the spatial decay of effects away from the excited end, if the harmonic excitation level is below a predetermined threshold.

In our study we approached the mixed problem in the context of linear theory of thermoelasticity for Cosserat bodies. After we define the finite energy solution for this mixed problem, some results with respect to the existence and uniqueness are proven of this kind of solution. To this aim, we generalized some analogous results established by Dafermos, for a mixed problem from linear theory of the classical elasticity. In another important result of our study, we introduce some specific conditions which give the possibility that the evolution of the finite energy solution to be controlled. [ABSTRACT FROM AUTHOR]

This paper introduces size-dependent modeling and investigation of the transverse vibrational behavior of rotating thermoelastic nanobeams by means of nonlocal elasticity theory. In the formulation, a model of thermal conductivity with two-phase delays (DPL) was utilized. By incorporating the interactions between phonons and electrons, this model took into account microstructural influences. Also, we have employed the state-space approach and Laplace transform approach to solve the governing equations, which were developed in the context of the nonlocal Eringen model. The nanobeam material is subjected to a changeable temperature field produced by the graphene tape attached to the nanobeam and connected to an electrical source. In addition, the nanobeam material is fully encompassed by an axially applied magnetic field. It has been revealed how coefficients such as the rotational angular velocity of the nanobeam, nonlocal coefficient, voltage, electrical resistance, and applied magnetic field influence its behavior. [ABSTRACT FROM AUTHOR]

Our study is a generalization of some results obtained by Synge in the classical theory of elasticity. By this extension, we wish to cover the theory of micropolar elastic bodies. More precisely, we approach the electroacoustic energy flux in the case of plane waves of harmonic type which propagate in piezoelectric crystals which are supposed to be prepolarized and prestressed. [ABSTRACT FROM AUTHOR]

We analyze a mathematical model for microstretch thermoelasticity with diffusion, in which each microelement is endowed with micro-concentrations and micro-temperatures. We study the linear, anisotropic case. By considering a certain Hilbert space, the mixed problem constructed in this context is reduced to an abstract problem in the centro-symmetric case. The well-posedness of the mathematical model is proven by using a semigroup of linear operators. [ABSTRACT FROM AUTHOR]

We consider the mixed initial‐boundary value problem in the context of the Moore‐Gibson‐Thompson theory of thermoelasticity for dipolar bodies. We consider the case of heat conduction with dissipation. Even if the elasticity tensors are not supposed to be positively defined, we have proven both, the uniqueness and the instability of the solution of the mixed problem. In the case that the mass density and the thermal conductivity tensor are positive, we obtain the uniqueness of the solution using some Lagrange type identities. [ABSTRACT FROM AUTHOR]

This study is concerned with the linear elasticity theory for bodies with a dipolar structure. In this context, we approach transient elastic processes and the steady state in a cylinder consisting of such kind of body which is only subjected to some boundary restrictions at a plane end. We will show that at a certain distance d = d (t) , which can be calculated, from the loaded plan, the deformation of the body vanishes. For the points of the cylinder located at a distance less than d, we will use an appropriate measure to assess the decreasing of the deformation relative to the distance from the loaded plane end. The fact that the measure, that assess the deformation, decays with respect to the distance at the loaded end is the essence of the principle of Saint-Venant. [ABSTRACT FROM AUTHOR]

In our paper, we consider a combination of two sub-cylinders coupled by an interface in a semi-infinite cylinder. Both sub-cylinders are made of dipolar elastic materials. For one of the two sub-cylinders, we will consider the elastostatic problem, and for the other the elastodynamic problem. Thus, the spatial behaviors of the sub-cylinders are of different kind and the question arises whether the evolution of this combination can be controlled. By using a polynomial way, we prove that the decay of solutions for the two problems can be controlled. [ABSTRACT FROM AUTHOR]

This study deals with the first initial boundary value problem in elasticity of piezoelectric dipolar bodies. We consider the most general case of an anisotropic and inhomogeneous elastic body having a dipolar structure. For two different types of restrictions imposed on the problem data, we prove two results regarding the uniqueness of solution, by using a different but accessible method. Then, the mixed problem is transformed in a temporally evolutionary equation on a Hilbert space, conveniently constructed based on the problem data. With the help of a known result from the theory of semigroups of operators, the existence and uniqueness of the weak solution for this equation are proved. [ABSTRACT FROM AUTHOR]

We shall transform the first boundary value problem of Elasticity for micropolar bodies in a variational form. For the operator of Elasticity, built in this context, we prove that it is positive definite. This property ensures the existence of a solution for the first boundary value problem and the possibility to approximate it by variational methods. [ABSTRACT FROM AUTHOR]

Consider a cylinder made of a microstretch thermoelastic material for which one plane end is subjected to plane boundary data varying harmonically in time. On the lateral surface and other base, we have zero body force and heat supply. By using a Toupin type measure associated with the corresponding steady-state vibration, and by assuming that the angular frequency of oscillations is lower than a certain critical frequency, we show that the amplitude of the vibrations decays exponentially with the distance to the base. This decay estimate is similar to that of the Saint-Venant type. [ABSTRACT FROM AUTHOR]

This paper is concerned with the nonlinear theory of micropolar, porous, and elastic solids. By using the theory of Langenbach, within this context, we obtain some existence and uniqueness results. [ABSTRACT FROM AUTHOR]

In this study, we will prove that the presence of the voids and of the internal state variables in an elastic body with dipolar structure have no effect on the result of uniqueness regarding the solution of the initial-boundary value problem from this context. First, we put down the basic equations and conditions which define the initial-boundary value problem in the context. Then, by means of three theorems, we prove some auxiliary estimates that underlie the result of uniqueness. Finally, by means of these estimates and by using the Gronwall's inequality, we prove our main result. [ABSTRACT FROM AUTHOR]

The objective of our study is to explain a boundary value problem, so called Saint-Venant relaxed problem, from the linear theory of Elasticity. We study the torsion of a cylindrical bar, by means of the torsion function, in the special case when the cross-section of the bar is conic. The bounary value problem, in this context, has been successfully solved. Also, we prove that there is no other cross section for what the considered problem has a solution. [ABSTRACT FROM AUTHOR]

In this article, a nonlocal thermoelastic model that illustrates the vibrations of nanobeams is introduced. Based on the nonlocal elasticity theory proposed by Eringen and generalized thermoelasticity, the equations that govern the nonlocal nanobeams are derived. The structure of the nanobeam is under a harmonic external force and temperature change in the form of rectified sine wave heating. The nonlocal model includes the nonlocal parameter (length-scale) that can have the effect of the small-scale. Utilizing the technique of Laplace transform, the analytical expressions for the studied fields are reached. The effects of angular frequency and nonlocal parameters, as well as the external excitation on the response of the nanobeam are carefully examined. It is found that length-scale and external force have significant effects on the variation of the distributions of the physical variables. Some of the obtained numerical results are compared with the known literature, in which they are well proven. It is hoped that the obtained results will be valuable in micro/nano electro-mechanical systems, especially in the manufacture and design of actuators and electro-elastic sensors. [ABSTRACT FROM AUTHOR]

The main concern of this study is an extension of some results, proposed by Green and Lindsay in the classical theory of elasticity, in order to cover the theory of thermoelasticity for dipolar bodies. For dynamical mixed problem we prove a reciprocal theorem, in the general case of an anisotropic thermoelastic body. Furthermore, in this general context we have proven a result regarding the uniqueness of the solution of the mixed problem in the dynamical case. We must emphasize that these fundamental results are obtained under conditions that are not very restrictive. [ABSTRACT FROM AUTHOR]

Our study is dedicated to the problem with initial and boundary conditions in the theory of thermoelasticity for micropolar materials with pores. We obtain some results regarding the existence and uniqueness of a finite energy solution of this mixed problem by generalizing the corresponding results obtained by Dafermos in the context of classical elasticity. In some specific conditions we prove some properties regarding the possibility to control the finite energy solution. [ABSTRACT FROM AUTHOR]