Effect of magnetic field and a mode-I crack problem in micropolar thermoelastic medium possessing under three theories

2014 ◽  
Vol 5 (2) ◽  
pp. 86-106 ◽  
Author(s):  
Khaled Lotfy ◽  
N. Yahia ◽  
W. Hassan

Purpose – A model of the equations of two-dimensional problems in a half space, whose surface in free of micropolar thermoelastic medium possesses cubic symmetry as a result of a mode-I crack is studied. There acts an initial magnetic field parallel to the plane boundary of the half-space. The crack is subjected to prescribed temperature and stress distribution. The formulation in the context of the Lord-Shulman theory includes one relaxation time and Green-Lindsay theory with two relaxation times, as well as the classical dynamical coupled theory. The paper aims to discuss these issues. Design/methodology/approach – The normal mode analysis is used to obtain the exact expressions for the displacement, microrotation, stresses and temperature distribution. Findings – The variations of the considered variables with the horizontal distance are illustrated graphically. Comparisons are made with the results in the presence of magnetic field. Originality/value – A comparison is also made between the three theories for different depths in 3D plots.

2015 ◽  
Vol 11 (4) ◽  
pp. 544-557 ◽  
Author(s):  
Mohamed I. Othman ◽  
W. M. Hasona ◽  
Nehal T. Mansour

Purpose – The purpose of this paper is to introduce the Lord-Shulman (L-S), Green-Naghdi of type III (G-N III) and three phase lag (3PHL) theories to study the effect of a magnetic field on generalized thermoelastic medium with two temperature. Design/methodology/approach – The problem has been solved numerically by using the normal mode analysis. Findings – The problem is used to obtain the analytical expressions of the displacement components, force stress, thermodynamic temperature and conductive temperature. The numerical results are given and presented graphically thermal force is applied. Comparisons are made with the results predicted by 3PHL, G-N III and L-S in the presence and absence of magnetic field as well as two temperature. Originality/value – Generalized thermoelastic medium.


2020 ◽  
Vol 16 (6) ◽  
pp. 1313-1335 ◽  
Author(s):  
Sunita Deswal ◽  
Devender Sheoran ◽  
Kapil Kumar Kalkal

PurposeThe purpose of this paper is to establish a model of two-dimensional half-space problem of linear, isotropic, homogeneous, initially stressed, rotating thermoelastic medium with microtemperatures. The expressions for different physical variables such as displacement distribution, stress distribution, temperature field and microtemperatures are obtained in the physical domain.Design/methodology/approachNormal mode analysis technique is adopted to procure the exact solution of the problem.FindingsNumerical computations have been carried out with the help of MATLAB programming, and the results are illustrated graphically. Comparisons are made to show the effects of rotation, time and microtemperatures on the resulting quantities. The graphical results indicate that the effects of rotation, microtemperatures and time are very pronounced on the field variables.Originality/valueIn the present work, we have investigated the effects of rotation, time and microtemperature in an initially stressed thermoelastic medium. Although various investigations do exist to observe the disturbances in a thermoelastic medium under the effects of different parameters, the work in its present form, i.e. the disturbances in a thermoelastic medium in the presence of angular velocity, initial stress and microtemperature have not been studied till now. The present work is useful and valuable for analysis of problems involving coupled thermal shock, rotation parameter, microtemperatures and elastic deformation.


2016 ◽  
Vol 04 (02) ◽  
pp. 1650004
Author(s):  
M. Bachher ◽  
N. Sarkar

An electromagneto-thermoelastic coupled problem for a homogeneous, isotropic, thermally and electrically conducting half-space solid whose surface is subjected to a thermal shock is considered in two-dimensional space. The equations of the theory of generalized electromagneto-thermoelasticity with fractional derivative heat transfer allowing the second sound effects are considered. An initial magnetic field acts parallel to the plane boundary of the half-space. The normal mode analysis and the eigenvalue approach techniques are used to solve the resulting nondimensional coupled field equations for the three theories. Numerical results for the temperature, displacements and thermal stresses distributions are presented graphically and discussed. A comparison is made with the results obtained in the presence and absence of the magnetic field.


2018 ◽  
Vol 14 (2) ◽  
pp. 306-321 ◽  
Author(s):  
Mohamed I.A. Othman ◽  
S.M. Abo-Dahab ◽  
Haneen A. Alosaimi

Purpose The purpose of this paper is to study a model of the equations of a two-dimensional problem in a half space, whose surface in a free micropolar thermoelastic medium possesses cubic symmetry as a result of inclined load. The problem is formulated in the context of Green-Naghdi theory of type II (G-N II) (without energy dissipation) and of type III (G-N III) (with energy dissipation) under the effect of magnetic field. Design/methodology/approach The normal mode analysis is used to obtain the exact expressions of the physical quantities. Findings The numerical results are given and presented graphically when the inclined load and magnetic field are applied. Comparisons are made with the results predicted by G-N theory of both types II and III in the presence and absence of the magnetic field and for different values of the angle of inclination. Originality/value In the present work, the authors study the influence of inclined load and magnetic field in a micropolar thermoelastic medium in the context of the G-N theory of both types II and III. Numerical results for the field quantities are obtained and represented graphically.


2015 ◽  
Vol 2015 ◽  
pp. 1-15 ◽  
Author(s):  
S. M. Abo-Dahab ◽  
Kh. Lotfy ◽  
A. Gohaly

The aim of the present investigation is to study the effects of magnetic field, relaxation times, and rotation on the propagation of surface waves with imperfect boundary. The propagation between an isotropic elastic layer of finite thickness and a homogenous isotropic thermodiffusive elastic half-space with rotation in the context of Green-Lindsay (GL) model is studied. The secular equation for surface waves in compact form is derived after developing the mathematical model. The phase velocity and attenuation coefficient are obtained for stiffness, and then deduced for normal stiffness, tangential stiffness and welded contact. The amplitudes of displacements, temperature, and concentration are computed analytically at the free plane boundary. Some special cases are illustrated and compared with previous results obtained by other authors. The effects of rotation, magnetic field, and relaxation times on the speed, attenuation coefficient, and the amplitudes of displacements, temperature, and concentration are displayed graphically.


2006 ◽  
Vol 74 (3) ◽  
pp. 586-589 ◽  
Author(s):  
David J. Unger

A continuous stress field for the mode I crack problem for a perfectly plastic material under plane stress loading conditions has been obtained recently. Here, a kinematically admissible velocity field is introduced, which is compatible with the continuous stress field obtained earlier. By associating these two fields together, it is shown that they constitute a complete solution for the uncontained plastic flow problem around a finite length internal crack, having a positive rate of plastic work. The yield condition employed is an alternative criterion first proposed by Richard von Mises in order to approximate the plane stress Huber-Mises yield condition, which is elliptical in shape, to one that is composed of two intersecting parabolas in the principal stress plane.


2005 ◽  
Vol 72 (1) ◽  
pp. 62-67 ◽  
Author(s):  
David J. Unger

A statically admissible solution for a perfectly plastic material in plane stress is presented for the mode I crack problem. The yield condition employed is an alternative type first proposed by von Mises in order to approximate his original yield condition for plane stress while eliminating most of the elliptic region as pertaining to partial differential equations. This yield condition is composed of two intersecting parabolas rather than a single ellipse in the principal stress space. The attributes of this particular solution of the mode I problem over that previously obtained are that it contains neither stress discontinuities nor compressive stresses anywhere in the field.


2018 ◽  
Vol 23 (1) ◽  
pp. 5-21 ◽  
Author(s):  
P. Ailawalia ◽  
S. Budhiraja ◽  
J. Singh

AbstractThe purpose of this paper is to study the two dimensional deformation in a generalized thermoelastic medium with microtemperatures having an internal heat source subjected to a mechanical force. The force is acting along the interface of generalized thermoelastic half space and generalized thermoelastic half space with microtemperatures having an internal heat source. The normal mode analysis has been applied to obtain the exact expressions for the considered variables. The effect of internal heat source and microtemperatures on the above components has been depicted graphically.


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