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In this paper, we are concerned with a time-dependent transmission problem for a thermo-electric-magneto-elastic solid immersed in an inviscid and compressible fluid. It is shown that the problem c...

This article examines the free vibrations of spherical orthotropic within an elastic medium according to the one-dimensional (1D) elastic model. According to the linear elasticity model, rotation, ...

Magnetic properties of electrical steels exhibit a strong sensitivity to mechanical stress; this phenomenon is known as magneto-elastic coupling. Mechanical stress affects microstructural features of soft magnetic materials, which in turn leads to a change in their magnetic characteristics. Therefore, the magneto-elastic coupling in these materials needs to be studied and modeled accurately. This paper is devoted to the development of an analytical magneto-elastic hysteresis model. A recently proposed analytical hysteresis model based on Kadar product approach is modified to model the magnetoelastic effects using a multi-scale approach. The proposed model is validated using the quasi-static hysteresis loops measured for a non-oriented (NO) material (M235-35A) subjected to uni-axial compressive stress and tensile stress. The proposed formalism is applicable to model the reversible effects of stress (in elastic range) and it offers a closed form equation. A stress-dependent coercive parameter is introduced in this equation using a simple numerical procedure. Thus the model can be implemented easily in circuit and field analyses.

Purpose Due to the increasing amount of high power density high-speed electrical machines, a detailed understanding of the consequences for the machine’s operational behaviour and efficiency is necessary. Magnetic materials are prone to mechanical stress. Therefore, this paper aims to study the relation between the local mechanical stress distribution and magnetic properties such as magnetic flux density and iron losses. Design/methodology/approach In this paper, different approaches for equivalent mechanical stress criteria are analysed with focus on their applicability in electrical machines. Resulting machine characteristics such as magnetic flux density distribution or iron are compared. Findings The study shows a strong influence on the magnetic flux density distribution when considering the magneto-elastic effect for all analysed models. The influence on the iron loss is smaller due to a high amount of stress-independent eddy current loss component. Originality/value The understanding of the influence of mechanical stress on dimensions of electrical machines is important to obtain an accurate machine design. In this paper, the discussion on different equivalent stress approaches allows a new perspective for considering the magneto-elastic effect.

A stress-based approach to the analysis of linear electro-magneto-elastic materials is proposed. Firstly, field equations for linear electro-magneto-elastic solids are given in detail. Next, as a counterpart of coupled governing equations in terms of the displacement field, generalized stress equations of motion for the analysis of three-dimensional (3D) problems Are obtained – they supply a more convenient basis when mechanical boundary conditions are entirely tractions. Then, a sufficient set of conditions for the corresponding solution of generalized stress equations of motion to be unique are detailed in a uniqueness theorem. A numerical passage to obtain the solution of such equations is then given by generalizing a reciprocity theorem in terms of stress for such materials. Finally, as particular cases of the general 3D form, the stress equations of motion for planar problems (plane strain and Generalized plane stress) for transversely isotropic media are formulated.

Inductive dynamic drives (IDD) are ultra rapid actuators where the moving part (disc) is subjected to impulse force. This paper presents the second model of inductive dynamic drive – a mechanical model where analytic- numerical approach was applied. The magnetic pressure, which was determined on the basis of the results obtained in the electrodynamic model, becomes the input data for mechanical model. Research with application of the mechanical model is necessary in order to determine the proper disc oscillation frequency and to obtain the stress state control for drive elements to be designed. Also, the selection of drive parameters to keep the disc deformation insignificant (while oscillating) is a condition under which these models do not need to be coupled together.

In this work the condition of the absolute stability on the derivative for control system of the deformation of the electro magneto elastic actuator is calculated..

The problem of stability of plane shock waves for a model of perfect magnetoelasticityis investigated. Important mathematical properties, like loss of strict hyperbolicityand loss of genuine nonlinearity, and their consequences for the stability ofmagneto-elastic shocks are discussed. It is shown that some of these shocks do not satisfyclassical Lax stability conditions. Both compressible and incompressible models ofmagneto-elasticity are discussed.[b]Keywords[/b]: perfect magneto-elasticity, shock waves, stability conditions

Based on the quasi-static approximation and taking into account the linearized equations for a prestressed electro-magneto-elastic medium, the problem of oscillations of a layered half-space with initial mechanical strains is considered. The Green function of an electro-magneto-elastic medium is constructed. The effect of the initial deformations in different medium parts on the phase velocities is considered. We took into account the deformations directed simultaneously to the compression and stretching of the half-space different parts. It was established that the initial mechanical deformations have various influence in different frequency domains.

This paper develops nonlocal elasticity equations and magneto-electro-elastic relations to size-dependent electro-magneto-elastic bending analyses of the functionally graded axisymmetric circular nanoplates based on the first-order shear deformation theory. All material properties are graded along the thickness direction based on exponential varying. It is assumed that a circular nanoplate is made from piezo-magnetic materials. The energy method and Ritz approach is employed for the derivation of governing equations of electro-magneto-elastic bending and the solution of the problem, respectively. The nanoplate is subjected to applied electric and magnetic potentials at top and transverse loads while it is rested on Pasternak’s foundation. Some important numerical results are presented in various figures to show the influence of applied electric and magnetic potentials, small scale parameter and inhomogeneous index of an exponentially graded nanoplate.

A structural parametric model of the multilayer electro-magneto-elastic actuator of nano and micro displacements is obtained based on solving matrix equations and used to find its transfer functions. Static and dynamic characteristics of such actuator are calculated. Multidimensional structural parametric model and parametric structural block diagram of the actuator are constructed. The way its geometric and physical parameters as well as the external load affect the actuator’s static and dynamic characteristics is found.

The mode III crack problem in a medium possessing coupled electro-magneto-elastic is considered. Two asymmetrical edge cracks emanate from an elliptical hole. Combined stress, electric and magnetic loads are considered. The elliptical hole and cracks are assumed to be either magneto-electrically impermeable or permeable. The closed-form solution for stress, electric and magnetic intensity factors are derived explicitly. Also the solution for energy release rate is given in closed form. The solution is based on the complex variable method combined with the method of conformal mapping. Numerical computations are given to illustrate the effect of variable geometrical and material parameters on stress, electric and magnetic intensity factors and energy release rate.

The object of the present paper is to investigate plane SH waves through a magneto-elastic crustal layer based over an elastic, solid semi space under the influence of surface stress on the free surface of the crustal layer and irregularity of the interface. Two types of irregularities of the interface namely, rectangular and parabolic have been considered. Modulations of wave velocity due to the presence of surface stress, irregularity and the magnetic field have been studied separately. Their combined effect has also been investigated. Graphs are drawn to highlight some important peculiarities. It is observed that surface stress, irregularity and magnetic field have their respective role to play in the propagation of SH waves in the crustal layer. Further modulation of wave velocity occurs due to their combined effect.

In this paper, the magnetic–elastic–plastic deformation behavior is studied for a ferromagnetic plate with simple supports. The perturbation formula of magnetic force is first derived based on the perturbation technique, and is then applied to the analysis of deformation characteristics with emphasis laid on the analyses of modes, symmetry of deformation and influences of incident angle of applied magnetic field on the plate deformation. The theoretical analyses offer explanations why the configuration of ferromagnetic rectangular plate with simple supports under an oblique magnetic field is in-wavy type along the x-direction, and why the largest deformation of the ferromagnetic plate occurs at the incident angle of 45° for the magnetic field. A numerical code based on the finite element method is developed to simulate quantitatively behaviors of the nonlinearly coupled multi-field problem. Some characteristic curves are plotted to illustrate the magneto–elastic–plastic deflections, and to reveal how the deflections can be influenced by the incident angle of applied magnetic field. The deformation characteristics obtained from the numerical simulations are found in good agreement with the theoretical analyses.

The trend in developing common rail injection systems goes to higher injection pressures and smaller minimum injected fuel masses. Multiple injection patterns generate pressure oscillations on the connection pipe between common rail and injector. These oscillations influence the amount and progression of the injected fuel mass and therefore the combustion process. As the oscillations depend on many different parameters, it is impossible to calculate their exact progression analytically. In this paper a new, non-invasive pressure sensor for measuring the pressure at the injector is introduced. It is based on the magneto-elastic effect and does not involve any mechanical elements. The physics on which the sensor is based are explained and the sensor design as well as a signal processing algorithm to reconstruct the pressure are illustrated. Measurement results are presented as well.

The aim of this paper is to introduce a general framework to model the coupled phenomena which occur when a system of solids is subjected to thermal, magnetic and mechanical loadings. This framework constitutes the basis of the numerical methods to be developed in order to perform coupled thermo-magneto-mechanical structural analyses of electrical machines. These general concepts are illustrated by different examples.

We report the results of an experimental study of a periodically forced elastic beam which swings between two stationary magnets. The beam itself has two magnets attached to it so that the system experiences strong magnetic coupling. Several routes to chaos are found including some which have not previously been reported for mechanical systems of this type. We have also investigated the effects of symmetry in the system and show that the bifurcation sets for the system exhibit systematic behaviour.

The motivation for this work has been a variety of motions like navigation of pipelines, insertion operations in assembly, and gripping actions, which require the adaptation of the mechanism to the external constraints, rather than avoid them. To this effect, efforts have been made towards building mechanisms that obtain the required degrees of freedom through deformations rather than explicit joints in them. Although the use of many joints provides the required number of degrees of freedom, it does so at the cost of making the system very bulky and complex. With the advent of new polymers, the possibility of building such mechanisms without joints, that fulfil the requirements of adaptation, have increased. Based on this approach, a Magneto Active Polymer (MAP) material has been developed in-house at the Texas A&M University, in which the actuation is performed by the conversion of electromagnetic energy into mechanical energy. The initial experimentation has proved the vast potential of the use of such a material, and a few mechanisms, like a magneto active peristaltic pump, have already been developed and tested, using this material. In this mechanism the pumping action is obtained when a moving magnetic field produces peristaltic waves in the magneto active material shaped as a tube. These waves help in pushing the fluid forward, in the tube. The advantage of this mechanism is that there is not physical contact of the actuating mechanism an the MAP tube, thereby reducing the wear. In developing the design for the peristaltic pump and other conceptual models described in this paper, ideas have been drawn from the different modes of locomotion and actuators used, in lower organisms and these have been good sources of inspiration for the work detailed in this paper.

This paper studies magneto-elastic Rayleigh waves on the surface of orthotropic cylinder of varying density. Solving three dimensional magneto-elastic equations frequency equations for axial waves are derived.

The magneto-elastic torsional wave in a bar under initial stress is studied. Most of the equations have been formulated on Biot’s incremental deformation theory and the initial stress has been taken in the form of uniform tension. Two cases have been considered: first when the material of the rod is homogeneous and second when it is non-homogeneous. In both the cases frequency equations for the wave have been calculated

The electro-magnetic equations of Maxwell and the equations of elasticity have been used to investigate the disturbances in an elastic bar acted upon by a magnetic field.

The influence of a uniform external magnetic field on the propagation of harmonic waves in a perfectly conducting elastic plate extending to infinity in vacuum, with its plane boundaries free of mechanical tractions, has been studied. With the plane of the field and the direction of wave propagation being normal to the plate, it is found that the effects of electromagnetic radiation into the adjoining free space cannot be neglected in the case of waves polarized in the plane. When the field is aligned with the direction of propagation, the maximum influence appears to be on long flexural waves, whereas if the field is normal to the plate then the effect is very much pronounced on long plate waves, and the flexural waves propagate almost with Alfvén velocity.

The propagation of plane waves in an electrically conducting cosserat medium placed in a magnetic field is investigated. The constitutive equations of cosserat elasticity developed recently byParia have been combined with the field equations of electromagnetism to obtain the basic equations for the problem. The results obtained in this investigation are in agreement with the corresponding results on magneto-elastic plane waves in Hookean solids when the cosserat constants are supposed to be absent.

Investigated is the steady state response to moving loads in an initially stressed magneto-elastic half-space bounded by a plane. The results obtained in this problem are in agreement with the corresponding classical results when the half space is supposed to be initially unstressed and non-magnetic.

The paper deals with the propagation of waves in a magneto-elastic initially stressed conducting layer. The wave velocity equation obtained is in agreement with the classical result of Rayleigh and Lamb when the layer is initially unstressed and the magnetic field isabsent.

The paper is concerned with the investigation of the magneto-elastic waves and disturbances in initially stressed conducting media. Firstly, (a) the steady state response to moving loads in a magneto-elastic initially stressed conducting medium under an uniaxial tension has been discussed. Secondly, (b) the Lamb's problem corresponding to a line load suddenly applied in a magneto-elastic initially stressed conducting half-space bounded by a plane under uniaxial tension has been investigated. The final results obtained in both cases are in agreement with the corresponding classical problems when the initial tension is zero and the magnetic field is absent.

Using GDQ method, the radial and circumferential stresses in an annular FGM plate with a uniform thickness under a transverse axisymmetric load is investigated. It is assumed that a uniform radial magnetic field acts on the top surface of the plate. The modulus of elasticity E and the magnetic permeability coefficient μ of the plate along its thickness are assumed to vary according to the volume distribution function. The Poisson's ratio ν is considered to be constant. Based on the classical plate theory (CPT), equilibrium equations are deduced and the displacement fields are determined. The radial and circumferential stresses as well as transverse and radial displacements are obtained accordingly. The effect of volume fraction function power m on the maximum deflection in the absence and presence of the magnetic field is also investigated. Moreover, the effect of t/a and b/a ratios on displacements, stresses, induction magnetic field intensity and the resulting Lorentz force are also investigated. According to the results, for different points along the radial direction, the application of radial magnetic field to the top surface of the plate completely changes the state of stress in both tangential and radial directions, resulting in tensile and compressive stresses in these two directions. The results also indicate that in presence of magnetic field, the plate displacement and stress components are lowered considerably.