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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.

A method for determining the magneto-elastic effects in spinel ferrites at high frequencies is presented. To investigate the high-frequency properties of different ferrite materials under stress, a reflection/transmission cell had been designed. In the measurement technique described here, we use a cell which based on a modified reflection/transmission line. This setup allows measurement of permeability under stress up to 20 MPa from 1 MHz to 10 GHz. Specific retrieval procedures have been developed to take into account the modifications in the line geometry. In this study, the permeability properties of spinel ferrites versus frequency between 1 MHz and 6 GHz as a function of the applied stress are showed. The two most important contributions of the permeability are the wall bulging and the gyro-magnetism which have a different behavior versus the applied stress.

Experimental evidence and theoretical analysis are presented for the bending of a soft ferromagnetic beam plate in a magnetic field. The experiments were conducted in the bore of a superconducting magnet at room temperature. Ferritic stainless steel SUS 430 is here used as the cantilever specimen for bending test. The experiments show the predicted increase in the deflection and strain with increasing magnetic field. The theoretical analysis is based on a classical plate bending theory for magneto-elastic interactions in a soft ferromagnetic material. Numerical calculations are carried out, and the deflection and strain are obtained for several values of magnetic field and geometrical parameter. A comparison of the deflection and strain is made between theory and experiment and the agreement is good for the magnetic field considered.

In our previous paper, it was confirmed that the unstable periodic orbit embedded in the chaotic attractor in magneto-elastic beam system can be stabilized by delayed feedback control experimentally. It seems an advantage that the control method does not require any exact model of the system. However, the application of the control raises the problem that we cannot predict the stabilized unstable periodic orbit until it converges. In this paper, an "onset window" is introduced to determine the onset timing for targeting the desired orbit embedded in the chaotic attractor experimentally. Moreover, the dependence of the stabilization on the delay and the gain parameters is also discussed based on the experimental results.

In both the series of ternary d-metal pnictides MnFeP1 − xAsx and MnRhP1 − xAsx the magnetic properties appear to be very sensitive to external parameters (temperature, pressure, magnetic field) and chemical composition. An extended analysis of previous experimental results is discussed in relation to the magneto-elastic phase transition in view of band structure calculations. The principal trends of these experiments are presented here.

A magneto-elastic beam system is described by the Duffing equation with delay feedback term. The perturbation technique leads to a general unstable periodic solution near the homoclinic orbit of the equation. A necessary and sufficient condition for stabilizing the solution is given as the relation between control parameters and initial constants. It is shown that sensitivity of the solution to initial constants implies chaos and fitting the parameters to the condition can control the chaos. Good agreement is found between the analytical results and previous experimental facts.

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.

A novel concept of lab-on-a-chip (LOC) type magneto-elastic resonant `micro-diver' system (MER-μDS) is reported. By combining magneto-elastic-alloy micro-resonator, microfluidic chamber/channels and embedded excitation/test coil, the microsystem realizes chip-scale bio-sensing in solution (~100 CFU/ml) with wireless signal-readout, which is favorable in real-time, on-site detection of pathogen in liquid food like milk and juice.

We construct different solutions of one-dimensional magnetoelastic problems. We analyze the process of propagation of disturbances in a magnetoelastic half-space with finite conductivity when a uniformly distributed force load and magnetic field intensity are prescribed on the surface.

Based on the concept of the energy-momentum tensor, the paper derives the conservation laws relevant to free energy and complementary free energy of electro-magneto-elastic media. From those laws, the path-independent integrals are presented. Other laws and associated integrals are also introduced. Some integrals are evaluated to obtain the energy release rate for the mode III electro-magneto-elastic fracture problem.

The aim of the finite element approach presented is to quantify the in-service elastic strains induced by variations of magnetic induction in structures made of soft ferromagnetic materials. Both strains induced by surface and body magnetic forces and pure magnetostriction strains are considered. >

The aim of this work is to present numerical data on the velocities of torsional vibrations of a perfectly conducting orthotropic hollow circular cylinder in the presence of an axail magnetic field. The extremes of the geometry are investigated. The values of the characteristic numbers governing the velocities of the first five models for various geometries of the circular cylinder are numerically computed. The phase velocities of the disturbances for the different wave numbers corresponding to the first five modes are calculated. It is found that torsional wave phase velocities increase with decreasing wall thickness of the hollow circular cylinder for all modes and increase with the higher modes of motion.

We proposed a smart actuator using magneto-elastic strain sensor. This actuator was cantilever-shape and composed by the strain sensor, a PZT plate and feedback system. In this smart actuator, a touching force at the free end was kept constant if the end was displaced. The smart actuator was sensitive for the touching force of less than 1 mN.

We report on structural, magnetic and magnetocaloric properties of MnxFe1.95-xP0.50Si0.50 (x > 1.10) compounds. With increasing the Mn:Fe ratio, a first-order magneto-elastic transition gradually changes into a first-order magneto-structural transition via a second-order magnetic transition. The study also shows that thermal hysteresis can be tuned by varying the Mn:Fe ratio. Small thermal hysteresis (less than 1 K) can be obtained while maintaining a giant magnetocaloric effect. This achievement paves the way for real refrigeration applications using magnetic refrigerants., 4 pages, 3 figures, Supplemental Material

The magneto-elastic interaction in cubic helimagnets with B 20 symmetry is considered. It is shown that this interaction is responsible for a negative contribution to the square of the spin-wave gap Δ and it alone appears to disrupt the assumed helical structure. It is suggested that competition between the positive part of Δ(I)(2), which stems from magnon-magnon interaction, and its negative magneto-elastic part leads to the quantum phase transition observed at high pressure in MnSi and FeGe. This transition has to occur when [Formula: see text]. For MnSi it was shown using rough estimations that at ambient pressure both parts Δ(I) and |Δ(ME)| are comparable with the experimentally observed gap. The magneto-elastic interaction is responsible for 2k modulation of the lattice where k is the helix wavevector and contributes to the magnetic anisotropy. Properties of the magnetic state above the quantum phase transition are also discussed. Experimental observation of the lattice modulation by x-ray and neutron scattering allows the determination of the strength of the anisotropic part of the magneto-elastic interaction responsible for the above phenomena and the lattice helicity.

The feasibility of contactless tunability of the band structure of two-dimensional phononic crystals is demonstrated by employing magnetostrictive materials and applying an external magnetic field. The influence of the amplitude and of the orientation with respect to the inclusion axis of the applied magnetic field are studied in details. Applications to tunable selective frequency filters with switching functionnality and to reconfigurable wave-guides and demultiplexing devices are then discussed.

The temperature dependence of the magnetization ,σ, the pressure effect on the Curie temperature, TC, and the thermal expansion for MnZnSb are measured. The value of dTC/dp is +3.6 K/kbar. Negative exchange strictions are observed for the lattice parameters a and c. The results are discussed using a phenomenological theory based on the molecular field theory.

In this paper a hysteresis model based upon an extended classical scalar Preisach hysteresis model is introduced. It is extended by the consideration of an offset of the hysteresis, because the Preisach function is a symmetric function and the consideration of an offset is one way to include a means to be able to model unsymmetric hysteresis.

We extend a general-relativistic ideal magneto-hydrodynamical code to include the effects of elasticity. Using this numerical tool we analyse the magneto-elastic oscillations of highly magnetised neutron stars (magnetars). In simulations without magnetic field we are able to recover the purely crustal shear oscillations within an accuracy of about a few per cent. For dipole magnetic fields between 5 x 10^13 and 10^15 G the Alfv\'en oscillations become modified substantially by the presence of the crust. Those quasi-periodic oscillations (QPOs) split into three families: Lower QPOs near the equator, Edge QPOs related to the last open field line and Upper QPOs at larger distance from the equator. Edge QPOs are called so because they are related to an edge in the corresponding Alfv\'en continuum. The Upper QPOs are of the same kind, while the Lower QPOs are turning-point QPOs, related to a turning point in the continuous spectrum., Comment: 6 pages, 1 figure, 1 table, Proceedings of NEB14, to appear in J. Phys.: Conf. Ser

The Young's Modulus (Y) and internal friction (δ) have been measured in the charge density wave (CDW) conductor NbSe 3 . Anomalies are clearly resolved in Y and δ at the upper CDW transition, T 1 (144K) and in Y at the lower CDW transition, T 2 (59K). Below 100K, Y has been measured in transverse magnetic fields up to 8T. Small field-induced stiffening effects are observed.

In this presentation I focus on the ferro- to paramagnetic transition in the manganese perovskites. I present a set of simple approximations which couple the relevant electronic degrees of freedom, the double exchange model, to local Jahn–Teller like lattice distortions. In a simplistic description, I show how this coupling controls the magnetism in the narrow band manganates, and how their critical behavior is influenced by the quasilocalization of Jahn–Teller polarons.

We have investigated the magneto-elastic effect at the antiferromagnetic phase transition in ${\text{LaMnO}}_{3}$ by neutron powder diffraction. The intensity of the (001) magnetic reflection decreases continuously to become zero at ${T}_{N}\ensuremath{\approx}141\text{ }\text{K}$ indicating a second-order antiferromagnetic phase transition. The lattice parameters $a$ and $b$ (space group $Pbnm$) of ${\text{LaMnO}}_{3}$ show well-defined anomalies close to ${T}_{N}\ensuremath{\approx}140\text{ }\text{K}$, whereas the third lattice parameter $c$ and the unit-cell volume show only weak anomalies. The present investigation shows strong magneto-elastic effect in ${\text{LaMnO}}_{3}$ close to ${T}_{N}$.

Magnetic properties of the MnFeAs y P 1− y system ( y = 0.2; 0.25; 0.30; 0.50) were examined in high dc magnetic fields of up to 20 T in the 4.2–400 K temperature range. Different first-order magnetic transitions were induced by the intense field and the magnetic phase H = T diagrams were deduced. These transitions were associated with magneto-elastic transitions observed in the absence of a field.

The paper discusses the wave propagation characteristics of two-dimensional magneto-elastic kagome lattices. Mechanical instabilities caused by magnetic interactions are exploited in combination with particle contact to bring about changes in the topology and stiffness of the lattices. The analysis uses a lumped mass system of particles, which interact through axial and torsional elastic forces as well as magnetic forces. The propagation of in-plane waves is predicted by applying Bloch theorem to lattice unit cells with linearized interactions. Elastic wave dispersion in these lattices before and after topological changes is compared, and large differences are highlighted.

This paper proposes a new device for magnetic field sensing that integrates a magneto-elastic rod as active material, with a Fiber Bragg Grating (FBG) strain sensor. Due to rate independent memory effects of the material, the response of the device is hysteretic and this lowers the device accuracy. Accurate modeling of material allows to embed in the device an algorithm for fast compensation of hysteresis so, yielding to a practically linear response of the sensor.

Propagation of longitudinal magneto-elastic waves in a conducting medium is considered. Dispersion characteristics for the medium without microstructure and Le Roux continuum are discussed. It is shown that wave propagation depends on the intensity of a magnetic field.

International audience; The prediction of the reversible evolution of macroscopic magnetostriction strain and magnetisation in ferromagnetic materials is still an open issue. Progress has been recently made in the description of the magneto-elastic behaviour of single crystals.Herein, we propose to extend this procedure to the prediction of the behaviour of textured soft magnetic polycrystals. This extension implies a magneto-mechanical homogenisation. The model proposed is discussed and the results are compared to experimental data obtained on industrial iron-silicon alloys.

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.

The high frequency GMI effect has been investigated on a variety of samples of Fe(62.5)Co(6)Ni(7.5)Zr(6)Cu(1)Nb(2)B(15), in the as-quenched state and submitted to conventional and joule heating thermal treatments, A comparison between high and low frequency GMI measurements is made, along with the study of the variation of the GMI effect as a function of both types of thermal treatments and of frequency, The high frequency low value of the GMI effect can be connected to the frequency dependence of the permeability relaxation, indicating that these soft ferromagnetic alloys are appropriate to be successfully utilised only at low frequencies.

Nowadays customised sensors and actuators are very important in order to optimise and control process parameters of engines, machines and other moving parts. Wireless interrogation of the sensors is necessary in order to gain information from hidden spots within the engine or from rotating shafts, axles or car tyres. Therefore we have exploited the possibility of using magneto-elastic wires as sensor elements to monitor the frictional conditions between the tyre and the roadway in order to enhance the active vehicle safety. In vehicles having wheels with rubber tyres, the deformation and forces that occur in the tyre material provide information about the driving status of the vehicle. Especially, it is possible to monitor current frictional conditions between the tyre and the roadway.

While a lot of research work has been done in the area of disaster prevention of large structural systems, very few methods have really been applied at field. The primary reason for this is the inherent complexity of most systems and the associated cost of instrumentation. The authors in this article have introduced the concept of utilizing a novel sensor technology for monitoring bridges. The technology is based on the principle of magnetostriction and work in this area is currently being carried out by the authors under a National Science Foundation International Cooperation grant involving researchers from both the United States and the Slovak Republic.

One of the interests of ferromagnetic glass-coated microwires is the possibility to engineer their anisotropy thanks to magneto-elastic effects. In this paper, we focus on the link between the stress models that have been established for these materials and the magneto-elastic behavior. We use the hysteresis loops under stress of microwires to determine their magneto-elastic properties. We compare the experimental magnetic anisotropy of many samples with different metallic core diameter and glass thickness with the magnetic anisotropy estimated using the magneto-striction coefficient and the total stress in the microwires: internal stress (coming from the elaboration process) and external stress (applied during the measurement).

The results of an experimental investigation into the elastic buckling of a soft cellular solid using magneto-static loading are reported. An electromagnet was used to apply a controlled force to an elastomer with embedded rare earth magnets. The resulting strain was found to induce an elastic buckling above a critical applied field strength. The buckling instability resulted in a rapid rotation of the sample which indicates potential as a fast switching mechanism for soft cellular materials.

Results are presented from an experimental study of the dynamics of a lightly-damped, flexible beam which is buckled and unbuckled magnetically. The system is parametrically excited by driving an electromagnet with a low-frequency sine wave. For voltage amplitudes in excess of the static bifurcation value, the beam will slowly switch between the one and two-well configurations. Experimental static and dynamic bifurcation results are presented. Poincaré sections of a chaotic steady-state are obtained for various values of the driving phase, and the correlation dimension of the chaotic attractor is estimated. Singular system analysis is used to demonstrate the effect of delay time on the noise level in delay-reconstructions, and to provide an independent check on the dimension estimate by directly estimating the number of independent coordinates from time series data.