جستجوی مقالات مرتبط با کلیدواژه « hollow cylinder » در نشریات گروه « مکانیک »

In this article, temperature and moisture distributions in a finite-length hollow cylinder made of functionally graded material (FGM) under transient coupled hygrothermal condition was presented. The coupled equations of heat conduction and moisture diffusion were solved employing the Fourier series expansion method along the longitudinal direction, the differential quadrature method (DQM) along the radial direction, and the Newmark method for the time domain. Finally, the history of temperature and moisture potentials was obtained. The effect of coupled and uncoupled hygrothermal loading, grading index, and hygrothermal boundary conditions was illustrated in numerical examples. Results show that the difference between the coupled model and uncoupled model is more obvious in the moisture rather than the temperature. Also, the negative grading index increases the temperature and moisture. While the effect of the positive grading index is vice versa. Moreover, to have a more accurate analysis of the transient hygrothermal process, it is important to employ the coupled model.

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.

Generalized thermoelastic models have been developed with the aim of eliminating the contradiction in the infinite velocity of heat propagation inherent in the classical dynamical coupled thermoelasticity theory. In these generalized models, the basic equations include thermal relaxation times and they are of hyperbolic type. Furthermore, Tzou established the dual-phase-lag heat conduction theory by including two different phase-delays correlating with the heat flow and temperature gradient. Chandrasekharaiah introduced a generalized model improved from the heat conduction model established by Tzou. The present work treats with a novel generalized model of higher order derivatives heat conduction. Using Taylor series expansion, the Fourier law of heat conduction is advanced by introducing different phase lags for the heat flux and the temperature gradient vectors. Based on this new model, the thermoelastic behavior of a rotating hollow cylinder is analyzed analytically. The governing differential equations are solved in a numerical form using the Laplace transform technique. Numerical calculations are displayed tables and graphs to clarify the effects of the higher order and the rotation parameters. Finally, the results obtained are verified with those in previous literature.

The present study aims to investigate the analysis of stress, strain, displacement, and electrical potential of a thick hollow cylinder made of FGPM under mechanical and thermal loads. Distribution of mechanical property of material is considered along the shell stick through the power distribution function. Thermal loads have been taken to signify the difference of temperature between outer and inner surfaces for each type of mechanical property. After extracting and solving the differential equations in transient state and the observation of mechanical and thermal boundary conditions, governing functions are obtained through the following parameters: thermal conduction non-homogeneous parameters, thermal linear distribution coefficient, elastic stiffness constant, piezo-electric coefficient, and dielectric constants.

In this article, the problem of time-dependent stress redistribution of a piezomagnetic rotating thick-walled cylinder under an axisymmetric hygro-thermo-magneto-electro-mechanical loading is analyzed analytically for the condition of plane strain. Using the constitutive equations, a differential equation is found in which there are creep strains. Primarily, eliminating creep strains, an analytical solution for the primitive electric and magnetic potential in addition to stresses is obtained. Then, creep strains are kept and creep stress rates are found by utilizing Norton’s law and Prandtl-Reuss equations for steady-state hygrothermal boundary condition. Lastly, the history of stresses and radial displacement as well as magnetic and potential fields during the time is obtained using an iterative method.  In the numerical examples, the effect of angular velocity, hygrothermal loading and thermal and moisture concentration dependency of elastic constants is investigated comprehensively.

In this paper, an analytical method is developed to obtain the solution for the one dimensional transient thermal and mechanical stresses in a hollow cylinder made of functionally graded material (FGM) and piezoelectric layers. The FGM properties are assumed to depend on the variable r and they are expressed as power functions of r but the Poisson’s ratio is assumed to be constant. Transient temperature distribution, as a function of radial direction and time with general thermal boundary conditions on the inside and outside surfaces, is analytically obtained for different layers, using the method of separation of variables and generalized Bessel function. A direct method is used to solve the Navier equations, using the Euler equation and complex Fourier series. This method of solution does not have the limitations of the potential function or numerical methods as to handle more general types of the mechanical and thermal boundary conditions.

The object of the present paper is to study heat conduction and thermal stresses in a hollow cylinder with nonhomogeneous material properties. The cylinder is subjected to sectional heating at the curved surface. All the material properties except for Poisson’s ratio and density are assumed to be given by a simple power law in the axial direction. A solution of the two-dimensional heat conduction equation is obtained in the transient state. The solutions are obtained in the form of Bessel’s and trigonometric functions. For theoretical treatment, all the physical and mechanical quantities are taken as dimensional, whereas we have considered non-dimensional parameters, for numerical analysis. The influence of inhomogeneity on the thermal and mechanical behaviour is examined. The transient state temperature field and its associated thermal stresses are discussed for a mixture of copper and tin metals in the ratio 70:30 respectively. Numerical calculations are carried out for both homogeneous and nonhomogeneous cylinders and are represented graphically.

In this paper, transient solution of two dimensional asymmetric thermal and mechanical stresses for a hollow cylinder made of piezoelectric material is developed. Transient temperature distribution, as function of radial and circumferential directions and time with general thermal boundary-conditions, is analytically obtained, using the method of separation of variables and generalized Bessel function. The results are the sum of transient and steady state solutions that depend upon the initial condition for temperature and heat source, respectively. The general form of thermal and mechanical boundary conditions is considered on the piezoelectric cylinder. Material properties of piezoelectric cylinder are the same along the thickness. A direct method is used to solve the Navier equations, using the Euler equation and complex Fourier series.

In this paper, an analytical solution for computing the linear plastic stresses, critical temperature and pressure in an FGM hollow cylinder under the internal pressure and temperature is developed. It has been assumed that the modulus of elasticity and thermal coefficient of expansion were varying through thickness of the FGM material according to a power law relationship. The Poisson''s ratio was considered constant throughout the thickness. The general forms of thermal and mechanical boundary conditions were considered on the inner surface. In the analysis section, the effect of nonhomogeneity in FGM cylinder was implemented by choosing a dimensionless parameter, named m, which could be assigned an arbitrary value affecting the stresses in the cylinder. Distribution of stresses in radial and circumferential direction for FGM cylinders under the influence of internal pressure and temperature gradient were obtained. Graphs of critical temperature and pressure versus radius of the cylinder were plotted. Cases of pressure and temperature loadings were considered separately. The direct method has been considered to solve the heat conduction and Navier equations. The outer pressure for all over the cylinder goes to the plastic region when ===0 and by increasing the modules of elasticity the pressure will increase. By substituting M=0 in radial linear plastic stress formula, the perfect plastic equation will yield. By putting , 0 pp rr rr r єє in radial linear plastic stress formula, it turns to the radial elastic stress.

In this paper, an analytical solution for computing the linear plastic stresses and critical pressure in a FGM hollow cylinder under the internal pressure due to non-Axisymmetric Loads is developed. It has been assumed that the modulus of elasticity was varying through thickness of the FGM material according to a power law relationship. The Poisson's ratio was considered constant throughout the thickness. The general form of mechanical boundary conditions is considered on the inside surfaces. In the analysis presented here the effect of non-homogeneity in FGM cylinder was implemented by choosing a dimensionless parameter, named m, which could be assigned an arbitrary value affecting the stresses in the cylinder. Distribution of stresses in radial, circumferential and shear directions for FGM cylinders under the influence of internal pressure were obtained. Graphs of variations of stress versus radius of the cylinder were plotted. The direct method is used to solve the Navier equations.

This paper deals with the determination of displacement function and thermal stresses of a finite length isotropic functionally graded hollow cylinder subjected to uniform temperature field. The solution of the governing thermoelastic equation is obtained, as suggested by Spencer et al. for anisotropic laminates. Numerical calculations are also carried out for FGM (Functionally graded material) system consisting of ceramic Alumina (Al2O3), along with Nickel (Ni) as the metallic component varying with distance in one direction and illustrated graphically.

In this paper, the general solution of steady-state one dimensional asymmetric thermal stresses and electrical and mechanical displacements of a hollow cylinder made of functionally graded material and piezoelectric layers is developed. The material properties, except the Poisson''s ration, are assumed to depend on the variable radius andthey are expressed as power functions of radius. The temperature distribution is assumed to be a function of radius with general thermal and mechanical boundary conditions on the inside and outside surfaces. By using the separation of variables method and complex Fourier series, the Navier equations in term of displacements are derived and solved.

In this paper, a general solution for torsion of hollow cylinders made of functionally graded materials (FGM) was investigated. The problem was formulated in terms of Prandtl’s stress and, in general, the shear stress and angle of twist were derived. Variations in the material properties such as Young’s modulus and Poisson’s ratio might be arbitrary functions of the radial coordinate. Various material models from the literature were also used and the corresponding shear stress and angle of twist were individually computed. Moreover, by employing ABAQUS simulations, finite element results were compared with the analytical ones.

In this paper, the classic coupled Magneto-thermo-elasticity model of hollow and solid cylinders under radial-symmetric loading condition (r, t) is considered. A full analytical and the direct method based on Fourier Hankel series and Laplace transform is used, and an exact unique solution of the classic coupled equations is presented. The thermal and mechanical boundary conditions, the body force, the heat source and magnetic field vector are considered in the most general forms, where no limiting assumption is used. This generality allows to simulate a variety of applicable problems. The results are presented for thermal and mechanical shock, separately, and compare the effect of magnetic field on temperature and displacement.