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This paper proposes a novel solution for the radially FGM cylinder subjected to thermo-mechanical shock. By discretizing the state space equation in the spatial domain and applying the time marching technique based on central difference, a semi-analytical solution to the thermoelastic dynamic behavior of cylinders is developed. The proposed solution technique has two advantages, one is suitable for the arbitrariness of material properties varying in the radial direction, and the other is applicable to different boundary conditions. Numerical examples for the cylinders with different graded material properties and two different boundary conditions are examined. The obtained results not only verify the correctness and effectiveness of the present solution, but also demonstrate the flexibility of the present method. The influences of gradient functions and boundary conditions on dynamic behavior are clearly displayed. The solution method is convenient and practical, which may help to freely select the gradient function for the design of FGM cylinders under various conditions. [ABSTRACT FROM AUTHOR]

Buoyancy-driven flow and heat transfer characteristics of the solid/hollow cylinders with concave shapes were numerically analyzed in a turbulent regime. The effects of Ra , L / D , and D th / D on heat dissipation have been studied in the range of 1010 to 1012, 2 to 10, and 0.2 to 0.9, respectively. It has been found that the Nu ¯ increases with Ra for solid/hollow cylinders. For a hollow cylinder, Nu ¯ in is always higher than Nu ¯ out except at D th / D = 0.2. The Nu ¯ in of a hollow cylinder increases up to D th / D = 0.6, irrespective of the Ra , and L / D ratios thereafter reduced drastically has been observed. Whereas, at a low D th / D , and high Ra (i.e., Ra ≥ 1011), Nu ¯ out of a hollow cylinder significantly decreases with D th / D . However, it shows a marginal decrement at a high length-to-diameter ratio. For solid and hollow cylinders, the thermo-fluid dynamics have been delineated through the temperature contours, streamline patterns, and vortex generation at the inner as well as outer wall of the hollow cylinder. This numerical study also proposes a correlation for the Nu ¯ of the solid/hollow cylinders to have an accuracy ± 6 % of relevant parameters. [ABSTRACT FROM AUTHOR]

Based on fractional thermoelastic diffusion theory, an infinite hollow cylinder with variable thermal conductivity and diffusivity is studied. The inner surface of the hollow cylinder is free and subjected to thermal and chemical shocks, while the outer surface is fixed and adiabatic. The closed forms of dimensionless displacement, temperature, chemical potential, stress, and concentration in the Laplace transform domain are given by eigenvalue method. These physical quantities are then numerically obtained through the inverse Laplace transformation. The effects of fractional order parameters, variable thermal conductivity and diffusivity on these quantities are discussed. The present model may be helpful for better understanding the thermoelastic diffusion problems in actual engineering. [ABSTRACT FROM AUTHOR]

In this paper, a numerical axisymmetric elastic stress wave propagation analysis of the 2D-FGM hollow thick finite cylinder has been performed. The new accurate material distribution model based on Mori-Tanaka scheme and third-order transition function for 2D-FGMs has been implemented in the graded finite element method with higher-order quadrilateral elements. A non-uniform impulsive pressure has been applied on the one-third of the top inner cylinder wall. Consequently, different wave velocities and reflections from the boundaries have been observed due to the graded distribution of material along with two directions. Moreover, the effects of two-dimensional material property distributions on the stress wave propagations and displacements through the cylindrical wall at different locations have been studied systematically. Normalized effective stresses based on von-Mises criteria has been performed in comparison with the internal impulsive pressure amplitude to provide a measure of the cylinder wall response to the mechanical impact loading, the effective stresses are nearly 2.5 times the internal pressure loading amplitude, closed to the impact location. According to the results, 2D material property gradations has effected the stresses significantly. Alternatively, desired stress values can be achieved through optimal design and appropriate choice of property distribution. [ABSTRACT FROM AUTHOR]

With the application of tiny components in scientific research and daily life, heat conduction and structural shape change in solids have attracted the idea of researchers. So further refinement of the theoretical model of thermo-viscoelastic hollow cylinders with fractional-order derivatives is the fundamental purpose of this study and development of fractional-order thermoelasticity theory with fractional-order strains to provide theoretical foundations for some thermodynamic practical applications (e.g., pipeline transport of gases or liquids) and selection of elastic and viscoelastic materials. In this paper, the dynamic response of the inner and outer surfaces of an infinitely sizeable hollow cylinder under the action of thermal shock is examined based on the fractional-order two-phase hysteresis theory and viscoelasticity theory. Convective boundary conditions are imposed on the inner and outer surfaces of the hollow cylinder and there is no traction on the inner and outer surfaces. The governing equations of the problem are established and solved by the Laplace transform method. In the numerical calculations, firstly, the effects of viscoelastic parameters on heat transfer as well as the stability of material structure are examined; secondly, the effects of fractional-order strain parameters on the model and their variations are examined; and finally, the effects brought about by the selection of hysteresis factors are examined. The results show that the introduction of the fractional order strain parameter has an important effect on the generalized thermoelastic model, and the viscoelastic parameter has a significant effect on the physical field of the hollow cylinder, especially the displacement and stress. [ABSTRACT FROM AUTHOR]

The flow-induced vibration of a circular cylinder with a hollow section that is mounted at the rear is investigated in this work via numerical simulation. The Reynolds number was limited in the range of 6918–1511 by using reduced velocity that corresponds to Ur = 2–12. Five typical center-to-center distance ratios L/D of 3, 4, 5, 6, and 7 and three hollow section positions of left bias, up bias, and middle of cylinder were selected. The displacement time history curve and short-time Fourier transform diagram show that when L/D = 3 and Ur = 3, the cylinder with the hollow position in the middle initially entered the main frequency vibration for 5.64 s, but when L/D = 4 and Ur = 6, the drag coefficient time history curve of the cylinder biased to the left and up at the hollow position demonstrated a "beating" phenomenon, and multiple frequency peaks appeared on the fast Fourier transform diagram. [ABSTRACT FROM AUTHOR]

A one-dimensional problem of elastic diffusion for a hollow orthotropic multicomponent cylinder under the action of external pressure, which is uniformly distributed over its inner and outer surfaces is considered. The mathematical model includes a system of equations of elastic diffusion in a cylindrical coordinate system, which takes into account relaxation diffusion effects, implying finite propagation velocities of diffusion processes. The problem is solved by the method of equivalent boundary conditions. For this an auxiliary problem is considered, whose solution is obtained by expansion into series in terms of the eigenfunctions of the elastic-diffusion operator. The relations that connect the right parts of the boundary conditions of both problems are constructed. These relations represent a system integral equation. They are solved using quadrature formulas. A calculation example for a three-component hollow cylinder is considered. [ABSTRACT FROM AUTHOR]

The hollow cylinder with a large diameter is the typical shell structure in major engineering applications such as aviation, aerospace, ocean, and so on. Unlike the geometric properties of transportation pipe, the shell structure has a large size and short length. It is relatively difficult to detect damage globally. According to the abovementioned characteristics, a damage localization method based on helical sensor network is proposed in the current research work to locate the internal damage in large-scale hollow cylinder in which the sensors are arranged on the outer surface of the structure. The wavefront theory about flexural modes is fully explored to determine helical sensor network which is suitable for the full frequency spectrum and avoids the approximate estimation to the wave in plate. The flexible sensing paths and single mode excitation in helical sensor network also provide more possibilities for the damage localization in hollow cylinder. The verification method of circumferential orders based on the Fourier transform is developed by the normal mode expansion approach. To apply the helical sensor network of flexural mode in damage localization, the effective loading length of flexural modes is investigated using simulation. And the simulation and experiment both are conducted to locate the internal damage in hollow cylinders and verify the credibility of proposed localization method. The scale parameter and sensing path number are further investigated to determine the effect on location accuracy. [ABSTRACT FROM AUTHOR]

Based on the one-dimensional elastic theory, the radial vibrations of cylindrical isotropic embedded in an elastic medium are studied in the paper. The effect of the magnetic field of the radial vibrations of an elastic hollow cylinder with rotation is researched as well. The one-dimensional equation of elastodynamic is solved in terms of radial displacement. The frequency equation is obtained when the boundaries are free and fixed; the mixed boundary condition is numerically examined. The determination is concerned with the eigenvalues of the natural frequency of the radial vibrations in the case of harmonic vibrations. The effect of the magnetic field and rotation on the natural frequencies were explored. It was shown that the dispersion curves of guided waves were significantly influenced by the magnetic field and rotation of the elastic cylinder. Numerical results are given and graphically illustrated in each considered case. The natural frequencies and mode shapes are calculated numerically, and the effects of rotating, magnetic field, and variable thickness are discussed. It is observed that an increase of the magnetic parameter, as well as the rotation parameters, brings results closer to the classical cylinder theory results. Furthermore, the current study can be applied to the design of microplates and nanoplates and their optimal usage. The results indicate that the effects of the magnetic field and rotation are very pronounced. [ABSTRACT FROM AUTHOR]

In the present work, we implement a graded finite element analysis to solve the axisymmetric 2D hyperbolic heat conduction equation in a finite hollow cylinder made of functionally graded materials using quadratic Lagrangian shape functions. The graded FE method is verified, and the simple rule of the mixture with power-law volume fraction is found to enhance the effective thermal properties' gradation along the radial direction, including the thermal relaxation time. The effects of the Vernotte numbers and material distributions on temperature waves are investigated in depth, and the results are discussed for Fourier and non-Fourier heat conductions, and homogeneous and inhomogeneous material distributions. The homogeneous cylinder wall made of SUS304 shows faster temperature wave velocity in comparison to the ceramic-rich cylinder wall, which demonstrates the slowest one. Furthermore, the temperature profiles along the radial direction when n = 2 and n = 5 are almost the same in all Ve numbers, and by increasing the Ve numbers, the temperature waves move slower in all the material distributions. Finally, by tuning the material distribution which affects the thermal relaxation time, the desirable results for temperature distribution can be achieved. [ABSTRACT FROM AUTHOR]

Present study primarily focuses on interpreting the propagation pattern of Shear horizontal (SH) wave in a piezo-composite layered cylinder. The structure consists of three concentric cylinders composed of hollow fiber-reinforced (FR) cylinder enclosed within piezomagnetic (PM) cylinder along the curved surface area which is similarly superimposed by a piezoelectric (PE) cylinder. The overall system is believed to be pre-stressed in a circumferential direction. The common boundary between each of the cylinder is demonstrated as imperfectly bonded. At the interface of PM and PE media, mechanical, electrical, magnetic and inter-coupled types of imperfections are assumed. Dispersion relations have been obtained for both the electrically open magnetically short (EOMS) and electrically short magnetically open (ESMO) circuit condition. Dispersion curves have been plotted to unravel the peculiarities of parameters like the radius of the hollow cylinder, thickness of FR and PM cylinder, thickness ratio of PM and PE cylinder, initial stress parameters, helical angle of the reinforcement. The influence of different interface parameters on the phase velocity of the wave has been studied and marked distinctly. For a detailed study, two successive modes have been plotted. Present study may help in improving the performance of piezo-composite cylindrical surface acoustic wave (SAW) sensors. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to perform thermo-mechanical deformation and stress analysis in a functionally graded (FG) hollow cylinder considering steady-state temperature distribution under the effect of rotation, gravity and constant heat generation. Design/methodology/approach: Navier's equation was used to solve the problem, and the obtained results were validated with benchmarks found to be in excellent agreement. The variation of temperature and other material properties such as Young's modulus, density, thermal expansion coefficient and thermal conductivity varied radially as per power-law variation. Findings: The effect of rotation was found to be vital compared to gravity and heat generation when compared individually and in combination. The results of displacement and stresses were presented for varying grading indices. Practical implications: FG cylinders have huge industrial applications as it opens the possibility of developing structures with a high strength/weight ratio. The present study will benefit industries in identifying the effective grading index that can be used by industries for fabricating FG structures. Originality/value: The effect of rotation, body force and heat generation on a cylindrical body has not been studied before. Furthermore, the combined effect of rotation, body force and heat generation has been studied to understand the behaviour of cylinders operating under similar conditions. [ABSTRACT FROM AUTHOR]

On the basis of the analysis of thermoelastic motion, the current research develops a novel model of modified thermoelasticity. The rotating long hollow cylinders with fixed surfaces are considered in a generalized Moore–Gibson–Thompson thermoelastic model (MGTTE) framework, including the modified Ohm's law. The cylinders are made of a thermoelastic material that rotates at a uniform rotational speed and is elastic in the transverse direction. The set of equations for the MGT heat conduction in the new model is built under the influence of the electromagnetic field by including a delay time in the context of Green–Naghdi of the third kind (GN-III). The inner boundary of the hollow cylinder is not only restricted but also sensitive to heat loading. The outer surface, on the other hand, is also restricted but insulates the heat. The Laplace transform method is utilized to deal with the differential equations produced in the new domain and transfer the problem to the space domain. The Dubner and Abate method is used to compute dynamically and graphically depict the theoretical findings for an isotropic transverse material. After comparing the results of several thermoelastic theories, the implications for the electromagnetic field are discussed. [ABSTRACT FROM AUTHOR]

The problem of calculating the optimal annealing modes of functionally gradient bodies was formulated. An original method of its numerical solution based on the principle of stepwise parametric optimization is used. The finite element method was used to solve direct problems during the iterative construction of optimal heating-cooling for bodies of complex geometric shape and structure. The search for the optimal value of the control function does not require zero approximation and at each time step the function of one variable can be minimized. [ABSTRACT FROM AUTHOR]

Based on the generalized nonlocal thermoelastic theory and the memory-dependent differential (MMD) theory, the dynamic response of the inner surface of an infinite hollow cylinder under thermal shock is investigated. The heat transfer coefficient varies linearly with the temperature, the outer surface of the hollow cylinder is insulated, and there is traction-free on the inner and outer surfaces. The governing equation of the problem is established, and the Laplace transform is used to solve the governing equation, and the distribution law of physical quantity is expressed by the modified Bessel function. In the numerical calculation, the influence of non-local parameters is firstly studied. Second, the influence of different thermal conductivity on various physical quantities is studied. Finally, the effects of time delay factor and kernel function on physical quantities are studied. The results show that the non-local parameters have little effect on temperature, but have significant effect on displacement and stress. The change of thermal conductivity has obvious influence on temperature, displacement, and stress. The hysteresis factor affects the extremum of a physical quantity. [ABSTRACT FROM AUTHOR]

In recent times, automotive manufacturing companies are focusing on developing components that is capable of increasing safety features associated with lightweight materials such as using aluminium. One such innovation is providing the vehicle with crash box, which is generally located at the front bumper. The function of the crash box is to safeguard the passenger by absorbing the kinetic energy of collision and self-deformation. In this paper, the authors presented a study of the compressive test applied on crash boxes with different types of honeycomb sandwich circular columns using 3D virtual modelling and finite element (FE) simulation with the help of Solidworks and Ansys Workbench respectively. This sandwich structure comprises two circular aluminium tubes filled with core shaped as a large-cell honeycomb lattice. Here, the crash boxes with three different honeycomb sandwich circular columns i.e., hexagonal, triangular, and semi-circular arrangement, were investigated and the energy absorption capabilities of these columns were studied. FE simulations were used to evaluate maximum stress that a material can sustain over a period under a load, material deformation, geometric changes, and load-displacement results using a constant material property of that of aluminium alloy, and the results of the three different arrangements were compared and it is known that the crash box with semi-circular arrangement has high energy absorbing capacity. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of the paper is to prepare the hygrothermal model with fraction order theory in a mathematical aspect. Design/methodology/approach: In this study, linear hygrothermoelastic theory is adopted to analyze and discuss the memory effect in a finite length hollow cylinder subjected to hygrothermal loading. Findings: Analytical solutions of temperature, moisture and stresses are obtained in this study by using the decoupling technique and the method of Integral transform. Originality/value: The paper deals with the original work based on hygrothermal response in hollow cylinder by theory of uncoupled-coupled heat and moisture. [ABSTRACT FROM AUTHOR]

The relations of a local gradient non-ferromagnetic electroelastic continuum are used to solve the problem of an axisymmetrical loaded hollow cylinder. Analytical solutions are obtained for tetragonal piezoelectric materials of point group 4 mm for two cases of external loads applied to the body surfaces. Namely, the hollow pressurized cylinder and a cylinder subjected to an electrical voltage V across its thickness are considered. The derived solutions demonstrate that the non-uniform electric load causes a mechanical deformation of piezoelectric body, and vice versa, the inhomogeneous radial pressure of the cylinder induces its polarization. Such a result is obtained due to coupling between the electromechanical fields and a local mass displacement being considered. In the local gradient theory, the local mass displacement is associated with the changes to a material's microstructure. The classical theory does not consider the effect of material microstructure on the behavior of solid bodies and is incapable of explaining the mentioned phenomena. It is also shown that the local gradient theory describes the size-dependent properties of piezoelectric nanocylinders. Analytical solutions to the formulated boundary-value problems can be used in conjunction with experimental data to estimate some higher-order material constants of the local gradient piezoelectricity. The obtained results may be useful for a wide range of appliances that utilize small-scale piezoelectric elements as constituting blocks. [ABSTRACT FROM AUTHOR]

We propose new methods for the determination of the thermal stressed state of viscoelastic bodies made of functionally graded materials subjected to annealing. We develop a numerical algorithm for the solution of the corresponding problem and realize it for the problems of heat conduction and thermoviscoelasticity. The thermal stressed state of a hollow cylinder is determined according to the given conditions of annealing. The variations of its temperature and stressed state are illustrated. [ABSTRACT FROM AUTHOR]

Scattering rates arising from the interactions of electrons with bulk longitudinal optical (LO) phonon modes in a hollow cylinder are calculated as functions of the inner radius and the uniform axial applied magnetic field. Now, the specific nature of electron-phonon interactions mainly depends on the character of the energy spectrum of electrons. As is well known, in cylindrical quantum wires, the application of a parallel magnetic field lifts the double degeneracy of the non-zero azimuthal quantum number states; m ≠ 0 ; irrespective of all electron's radial quantum number l states. In fact, this Zeeman splitting is such that the m < 0 electron's energy subbands initially decrease with the increase of the parallel applied magnetic field. In a solid cylinder, the lowest-order; { l = 1 ; m = 0 } subband is always the ground state. In a hollow cylinder, however, as the axial applied magnetic field is increased, the electron's energy subbands take turns at becoming the ground state; following the sequence { m = 0 , - 1 , - 2... - N } of azimuthal quantum numbers. Furthermore, in a hollow cylinder, in general, the electron's energy separations between any two subbands are less than the LO phonon energy except for exceptionally high magnetic fields, and some highest-order quantum number states. In view of this, the discussion of the energy relaxation here is focused mainly on intrasubband scattering of electrons and only within the lowest-order { l = 1 ; m = 0 } electron's energy subband. The intrasubband scattering rates are found to be characterized by shallow minima in their variations with the inner radius, again, for a fixed outer radius. This feature is a consequence of a balance between two seemingly conflicting effects of the electron's confinement by the inner and outer walls of the hollow cylinder. First; increased confinement of the charge carriers generally leads to the enhancement of the rates. Second; the presence of a hole in a hollow cylinder leads to a significant suppression of the scattering rates. The intrasubband scattering rates also show a somewhat parabolic increase in their variations with the applied magnetic field; an increase which is more pronounced in a relatively thick hollow cylinder. [ABSTRACT FROM AUTHOR]

The dynamic response of a hollow cylinder subjected to a hygrothermal coupled shock is studied. The memory-dependent differential is introduced into the heat transfer equation and the diffusion equation, and a memory-dependent differential generalized hygrothermal coupling model is developed. In this article, Laplace transform and inverse transform are used to find the closed-form solutions of various physical quantities. The influence of the hysteresis factor and the kernel function on the distribution of each physical quantity is analyzed and the time history of the hygrothermal coupling is studied. The numerical results show that the larger the ratio of temperature gradient hysteresis factor to heat flux hysteresis factor, the faster the wave speed. Also, the hysteresis factor affects the wave crest. For the time course of hygrothermal, it is once again verified that the hygrothermal wave has a finite propagation speed. At the same time, we can get the conclusion that the wave is dominated by fluctuations in the early stage after the onset of hygrothermal shock. The above findings are of reference value for the structural design and optimization of tubes in a hygrothermal environment. [ABSTRACT FROM AUTHOR]

Copyright of Engineering Mechanics / Gongcheng Lixue is the property of Engineering Mechanics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, thermal and mechanical stresses in hollow thick-walled functionally graded (FG) cylinders is presented under the convection boundary condition. The convective external condition and constant internal temperature in hollow cylinders are investigated. Inhomogeneous material properties produce irregular and two-point linear boundary value problems that are solved numerically by the pseudospectral Chebyshev method. The displacement and thermal stress distributions are examined for two different material couples under particular boundary conditions that are similar to their real engineering applications. Results have demonstrated that the pseudospectral Chebyshev method has low computation costs, high accuracy and ease of implementation and can be easily customized to such engineering problems. [ABSTRACT FROM AUTHOR]

The analytical and numerical analysis on the transient displacement and stress fields subjected to the electric load E z and E r in the electrostrictive hollow cylinder are studied in this paper. The electric and stress fields are uncoupled to derive the analytical solutions first. Then, the discussed displacement is decomposed into a quasi-static solution which satisfies inhomogeneous boundary conditions and a dynamic solution which satisfies homogeneous and initial conditions. After the quasi-static solution has been solved, the dynamic solution can be derived by using the methods of Hankel and Laplace transforms. Finally, the numerical examples are given to study the mechanism of dynamic stresses in case of different electric loads and structure sizes. It is concluded that the method and the process of the computing are simple, effective and accurate for the discussed problem and can easily be used in engineering design. [ABSTRACT FROM AUTHOR]

In any sensory system, the Electromagnetic (EM) shielding of the channel-carrying signal is a fundamental technique to provide a noise-immune measurement system. Severe failures and uncertainty may occur if the external EM fields interfered with the measurements. Typically, the shielding is realized by enclosing the channel-carrying signal with thinconductive hollow structures. However, with such structures, it is required to provide access to the interior components from the outside, for wires' connections, or better heat dissipation. This can be considered as a weakness in such the external magnetic fields can penetrate through the shielding structure. In this paper, the EM shielding effectiveness is considered for long hollow-cylinder structures with slots. The induced eddy current in thin-conductive shielding systems with slots together with the magnetic fields at different conditions are modeled. The objective is to determine the impact of the integrated slots along with the structure. The influence of the slots' sizes (𝛂) and position relative to the excitation magnetic field (i.e., the declination angle (𝛃)) are investigated to evaluate the shielding effectiveness by means of the determination of the shielding factor. The results reveal the inherent relationship between the shield parameters and shielding effectiveness. The shielding effectiveness deteriorates by the slots' integration within the shielding surface. However, decreasing the size of the slots improves the shielding, significantly, towards the shielding effectiveness of the continuous cylindrical structure. Additionally, utilizing the symmetry in the structure positioning the slots in the direction perpendicular to the magnetic field flux improves the shielding effectiveness, drastically. Such a model can be considered to evaluate the degree of effectiveness or success of integrating opening slots within the shielding structure, which can be applied to different types of instrumentation systems specifically at the sensor-electronics interface. [ABSTRACT FROM AUTHOR]

The classical Fourier heat conduction theory as well as the widely used Fick's diffusion law predicts an infinite wave velocity. This is physically unrealistic. By generalizing the classical Fourier's and Fick's laws, this paper presents a hyperbolic diffusion law to apply heat and moisture coupling. The transient response of the hygro-thermo-elastic field in infinitely long hollow cylinders subjected to sudden heat and moisture shock on the inner and outer surfaces is studied. With the aid of the Laplace transform and the decoupling technique, the closed-form solutions of temperature, moisture, elastic displacement and stresses are determined respectively. The analytical results show that the thermal and moisture relaxation time effect between temperature and moisture is significant for composites. Compared with the classic counterpart, the finite hygrothermal wave speed of the pipe is achieved and decreases with the relaxation time rising. The temperature, moisture, elastic displacement and stresses are calculated. Numerical results are displayed graphically to show the influence of the phase lag of heat/moisture flux on the response of the hygro-thermo-elastic fields. Non-Fourier and non-Fick effects are remarkable between the classic model and hyperbolic hygrothermal coupling model. Some drawbacks induced by the classical Fourier's and Fick's laws are averted. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Central South University is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper aims to develop semi-analytical results of the poromechanical fields in a hollow cylinder subjected to an asymmetric loading condition. The poroelastic properties of the hollow cylinder vary in the radial direction. The heterogeneous hollow cylinder is approximated by a multilayer structure in which each cylindrical layer is assumed to be homogeneous. The analytical results of the poromechanical field are first established in the transformed Laplace space, and then the ones in time space are obtained by the inverse Laplace transformation. They are perfectly in coherence with existent results in the literature that were developed for the homogeneous and the heterogeneous cases at the steady state regime. Sensitivity analysis shows a significant effect of the radial variations of the poroelastic properties on the response of the hollow cylinder. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the history of radial displacement, stresses, electric potential, and magnetic potential of a functionally graded magneto-electro-elastic (FGMEE) hollow cylinder subjected to an axisymmetric hygro-thermo-magneto-electro-mechanical loading for the plane strain condition. The material properties are taken as a power-law function of radius. Using stress-displacement relations, equations of equilibrium, electrostatic and magnetostatic equations, we find a differential equation including creep strains. Initially, eliminating creep strains, we obtain an analytical solution for the primitive stresses and electric and magnetic potential. In the next step, considering creep strains, we find the creep stress rates by applying the Norton law and Prandtl–Reuss equations for steady-state hygrothermal boundary condition. Finally, using an iterative method, we find the time-dependent creep stresses, radial displacement, and magnetic and potential field redistributions at any time. In numerical section, are comprehensively investigate the effects of grading index, hygrothermal environmental conditions, rotating speed, and temperature- and moisture-dependency of elastic constant of FGMEE. [ABSTRACT FROM AUTHOR]

The present article deals with the magneto-thermoelastic interactions in a transversely isotropic hollow cylinder. In the presence of the magnetic field, the governing equations are formulated for three-phase-lag model of generalized thermoelasticity. A vector-matrix differential equation is formed by using Laplace transform which is solved by the eigenvalue approach. In order to obtain the stress, displacement and temperature field, the field functions are expressed in terms of the modified Bessel functions in the Laplace transformed domain. When the outer radius of the hollow cylinder tends to infinity, the corresponding results are discussed. Finally, an appropriate Laplace transform inversion technique is adopted and comparison of three generalized thermoelastic theories for the considered parameters is presented graphically. [ABSTRACT FROM AUTHOR]

This work attempts to present mathematical modeling of the dynamics of the hydroelastic system consisting of a hollow cylinder with inhomogeneous initial stresses and a compressible barotropic inviscid fluid which filled the interior of the cylinder. The motion of the cylinder is described with the 3D linearized theory of elastic waves in bodies with initial stresses; however, the flow of the fluid is described with the linearized Euler equations for compressible inviscid fluid. Formulations of the boundary conditions on the outer surface of the cylinder and compatibility conditions between the cylinder and fluid on the interior surface of the cylinder are presented. Concrete formulations are made for the axisymmetric case, and general aspects of the solution methods of the formulated problems are considered. Under these considerations, two types of problem are selected: (1) the axisymmetric longitudinal wave propagation and (2) fluid flow profile on the outer free surface of the cylinder—the "circular" radial moving load. Numerical results are presented and discussed for the first type of problem. In particular, it is established that the character of the influence of the inhomogeneous initial stresses on the wave propagation velocity in the hydroelastic system under consideration depends on the dimensionless wavenumber. The perspective of future investigations is also presented and discussed. [ABSTRACT FROM AUTHOR]

The Distribution of displacements and stresses in a finite length hollow cylinder made of functionally graded material (FGM) subjected to coupled hygrothermal loading was investigated. The simply supported cylinder was under a transient coupled hygrothermal loading. Furthermore, the internal pressure and viscoelastic foundation can be considered for the cylinder. The coupled equations of heat and moisture transfer and motion equations of the cylinder were solved employing the Fourier series expansion method, the differential quadrature method (DQM), and the Newmark method along the longitudinal direction, the radial direction, and the time domain, respectively. Finally, the distribution of temperature, humidity, deformations, and stresses was obtained. The effects of coupled and uncoupled hygrothermal loading, grading index, hygrothermal boundary condition, and viscoelastic foundation are illustrated in the numerical examples. The results show that the FGM cylinder touches the temperature balance before using the uncoupled model rather than the coupled model. Moreover, by serving the time, the radial displacement, and maximum hoop stress increase, and longitudinal displacement decreases to reach steady-state condition. [ABSTRACT FROM AUTHOR]

A study is presented to observe the effect of residual stress on waves in an incompressible, hyper-elastic, thick and hollow cylinder of infinite length. The problem is based on the non-linear theory of infinitesimal deformations occurring after a finite deformation. A prototype model of strain energy function is used which adequately includes the effects of residual stress and deformation. The expressions for internal pressure and the axial load are calculated and graphical illustrations are presented. Analysis of infinitesimal wave propagation is carried for the axisymmetric case in the considered cylinder. Numerical solution is obtained in the undeformed configuration and analyzed for the two-point boundary-value problem. Dispersion curves are plotted for varying choice of parameters. [ABSTRACT FROM AUTHOR]

We propose a procedure of control over the speed of response of thermal conditions in the case of thermal loading of the bodies of revolution made of functionally graded materials. The construction of solutions of the analyzed problems is based on numerical methods. To solve direct problems, we use the method of weighed residuals and the finite-element method. The solution of the posed extreme problem is based on the principle of step-by-step parametric optimization. [ABSTRACT FROM AUTHOR]

A method and calculation results are presented for the flow field and convective heat transfer in a hollow cylinder having an end wall and rotating about the axis of symmetry under variation of the angular velocity of rotation and cylinder height. [ABSTRACT FROM AUTHOR]

Copyright of Scientific Bulletin of National Mining University is the property of National Mining University, State Higher Educational Institution and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

An exact solution of a thermal shock for a circular cylinder is presented. A refined multi-dual-phase-lag generalized thermoelasticity model is proposed. The application of initial conditions without using Laplace transform is effected. The exact solutions of main physical fields are obtained analytically in the radial direction using the normal mode technique. For the case where the mechanical and thermal loads are applied on the inner and outer surfaces of the cylinder. Numerical results for the distributions of radial displacement, temperature, radial, hoop, and axial stresses are illustrated graphically. Extensive results are tabulated to show the accuracy of the present model. The results will also be used as benchmarks for forthcoming comparisons with other investigations. The results indicate that the effects of internal and external pressures and time are very pronounced. [ABSTRACT FROM AUTHOR]

Copyright of Engineering Mechanics / Gongcheng Lixue is the property of Engineering Mechanics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The axisymmetric torsion of a layer of incompressible Mooney–Rivlin material placed between two rigid coaxial cylindrical surfaces is considered. It is assumed that the ends of the cylinder are fixed to avoid axial displacement and the cross-sections orthogonal to the axis of symmetry do not distort during deformation. In this case, the material points move along arcs of circles with an angular velocity which in the general case may depend on both the axial and the radial coordinates. Closed-form solution of the equilibrium equation is obtained. The well-known Rivlin solution is a particular case of this solution. Like in the classical solution, the stress tensor is a function of only the radial coordinate and the twist angle of the material points is a linear function of the axial coordinate. It is shown that torsion that is symmetric about a plane orthogonal to the axis of rotation can be realized only within the framework of the Rivlin solution. The obtained exact solution can be realized in the presence of friction on cylindrical surfaces. The initial-boundary-value problem described by this solution is considered. [ABSTRACT FROM AUTHOR]

With the development of micro/nanoscale electromechanical systems and the wide applications of ultrashort pulse lasers, the classical and hyperbolic hygrothermal coupled models fail to predict the micro/nanoscale hygrothermoelastic responses. This paper presents a dual-phase-lag hygrothermal coupled model to analyze the transient responses of an infinitely long hollow cylinder subjected to hygrothermal loadings at the inner surface. By using the method of separating variables and the Laplace transform, the closed form solutions of temperature, moisture, displacement and stresses are obtained. The effects of the phase-lags of heat flux, moisture flux, temperature gradient and concentration gradient on the responses are calculated and displayed graphically. The present results are also compared with those based on the classical and hyperbolic models, which can be viewed as two special cases of the dual-phase-lag model. It can be shown that the phase-lags parameters play an essential role in controlling the heat and moisture transfer process. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering Research (2307-1877) is the property of Kuwait University, Academic Publication Council and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The two main research orientations on the problem of hydrogen embrittlement are examined: the study of fundamental principles and the disclosure of micromechanisms and the relation between hydrogen embrittlement and metal aging; the development of models and methods for predicting the kinetics of change in stress-strain state and for evaluating the longevity of structures subjected to hydrogen embrittlement. The state of the problem of hydrogen embrittlement of metals in the first direction is briefly analyzed. More attention is paid to the importance of predicting the behavior of charged metal structures under the influence of hydrogen embrittlement. We then examine the use of finite element modeling using the ANSYS software to compute the calculation analysis of a hollow cylinder subjected to internal and external pressures and hydrogen embrittlement. The cylinder material is nonlinear elastic and its properties depend on the hydrogen concentration at each point of the cylinder. Consideration is given to the influence of the rigidity of the stress state and the hydrogen concentration on the diffusion kinetics of hydrogen in the cylinder body. The problem is solved in time steps. The distributions of the hydrogen concentration and the stresses for a quarter of the volume of the cylinder are given, as well as the graphs of these values according to the thickness of the wall of the cylinder at different times. It is shown that the ANSYS software package adapted to the resolution of such problems can model the behavior of different structures in a hydrogen containing environment, taking into account the effects caused by both the influence of hydrogen on mechanical properties of the material and by the stress state of the structures, as well as by the influence of the stress state on the interaction kinetics of hydrogen with the structures. [ABSTRACT FROM AUTHOR]

In this paper, thermo-electro–elastic behavior of a hollow cylinder made of carbon nanotubes bundles–reinforced electro-active polymer considering the hierarchical structure of carbon nanotube bundles is investigated. Material properties of carbon nanotube bundles are calculated on the basis of the rule-of-mixtures, and material parameters of the composite are computed in accordance to the self-consistent micromechanical model. Utilizing the finite difference method and numerical solutions for thermo-electro–elastic behavior of the carbon nanotubes bundles–reinforced electro-active polymer hollow cylinder under thermal, electric, and mechanical loads are obtained. Numerical examples show the influences of electric load, thermal load, and material properties, geometric parameters, and boundary conditions on the thermo-electro–elastic behavior of carbon nanotubes bundles–reinforced electro-active polymer cylindrical structures. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to deal with the three-dimensional analysis of free vibrations in a stress-free and rigidly fixed homogeneous transversely isotropic hollow cylinder in the context of three-phase-lag (TPL) model of hyperbolic thermoelasticity. Design/methodology/approach: The matrix Frobenius method of extended power series is employed to obtain the solution of coupled ordinary differential equations along the radial coordinate. Findings: The natural frequency, dissipation factor and inverse quality factor in the stress-free and rigidly fixed hollow cylinder get significantly affected due to thermal vibrations and thermo-mechanical coupling. Originality/value: The modified Bessel functions and matrix Frobenius method have been directly used to study the vibration model of a homogeneous, transversely isotropic hollow cylinder in the context of TPL model based on three-dimensional thermoelasticity. [ABSTRACT FROM AUTHOR]

This paper studies the influence of the inhomogeneous initial stress state in the system consisting of a hollow cylinder and surrounding elastic medium on the dynamics of the moving ring load acting in the interior of the cylinder. It is assumed that in the initial state the system is compressed by uniformly distributed normal forces acting at infinity in the radial inward direction and as a result of this compression the inhomogeneous initial stresses appear in the system. After appearance of the initial stresses, the interior of the hollow cylinder is loaded by the moving ring load and so it is required to study the influence of the indicated inhomogeneous initial stresses on the dynamics of this moving load. This influence is studied with utilizing the so-called threedimensional linearized theory of elastic waves in elastic bodies with initial stresses. For solution of the corresponding mathematical problems, the discrete-analytical solution method is employed and the approximate analytical solution of these equations is achieved. Numerical results obtained within this method and related to the influence of the inhomogeneous initial stresses on the critical velocity of the moving load and on the response of the interface stresses to this load are presented and discussed. In particular, it is established that the initial inhomogeneous initial stresses appearing as a result of the action of the aforementioned compressional forces cause to increase the values of the critical velocity of the moving load. [ABSTRACT FROM AUTHOR]

The characteristics of thermally induced failure are investigated for a hollow circular cylinder exposed to a convective cooling at the inner surface. The transient fields of both temperature and thermal stresses are given in closed forms over the full range of Biot number. The thermal shock resistance (TSR) is analyzed based on two distinct failure criteria. Namely, the strength-based failure criterion is adopted for a nearly flaw-free cylinder while the fracture toughness-based one is used for the counterpart with an inner crack-like flaw. From each criterion, the admissible maximum temperature drop is obtained assuring that a hollow cylinder can tolerate without failure. The influence of flaw size on the TSR is quantified and a criterion-selection diagram is proposed for the TSR characterization. These results are deemed to be of importance from the perspective of estimating the TSR of a hollow circular cylinder. [ABSTRACT FROM AUTHOR]

Three groups of fracturing tests in two-phase fluids of CO SB 2 sb and water were conducted, where the pressure of CO SB 2 sb was set at 3.0 MPa, 3.4 MPa, and 3.7 MPa, respectively. It can be observed that the CO SB 2 sb saturation after the displacement range from 44.15% to 68.43%, i.e., the CO SB 2 sb saturation goes up with the increase of CO SB 2 sb displacement pressure. As the confining pump was operated in a constant-pressure mode, when the CO SB 2 sb flowed into the confining pressure chamber through the sample during the fracturing, the piston was moved back by the pump for stabilizing the pressure, thus yielding negative flow rate. [Extracted from the article]

The paper deals with the study of the influence of the non-homogeneous prestresses in the system consisting of the hollow cylinder and surrounding elastic medium on the frequency response of this system caused by the time-harmonic ring load acting in the interior of the cylinder. The axisymmetric problem is considered and it is assumed that in the initial state, the system is compressed in the radial direction with homogeneously distributed static forces as a result of which, non-homogeneous pre-stresses (or initial stresses) appear in that. It is also assumed that after these pre-stresses appear in the interior of the cylinder, the point-located (with respect to the axial coordinate directed along the cylinder's central axis) additional time-harmonic ring load acts. Thus, it is required to determine how the pre-stresses influence the frequency response of the system to the noted additional time-harmonic loading. This influence, which is the non-linear effect, is studied within the scope of the so-called three-dimensional linearized equations and relations of the theory of elastic waves in pre-stressed bodies. The solution to the corresponding boundary value problems is found by employing the discrete analytical solution method and numerical results on the influence of the pre-stresses on the frequency response of the interface stresses which appear as a result of the action of the additional time-harmonic forces, are presented and discussed. In particular, it is established that the pre-stresses mentioned above cause to decrease the magnitude of the interface dynamic stresses appearing as a result of the additional time-harmonic loading. [ABSTRACT FROM AUTHOR]

Copyright of Engineering Mechanics / Gongcheng Lixue is the property of Engineering Mechanics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Magnetic flux generated by neodymium-iron-boron magnets of three different configurations are calculated and compared by using COMSOL Multiphysics simulation. For a magnetic ring, the substantial flux density of 0.6-0.7 T is obtained in the bore and the edge. The values are increased beyond 1 T in the gap between inner and outer concentric rings in the second structure. The magnetic flux density is fairly uniform in the circumferential direction. Finally, moderate fields around 0.6 T in spaces between magnetic bars arranged into concentric arrays can be utilized. In this structure, the magnetic flux density along the radial direction measured from the center of the ring peaks at two distances corresponding to two arrays of magnets. These different profiles of magnetic field can be implemented in devices and experiments of different requirements. [ABSTRACT FROM AUTHOR]