Magnetomechanical Hysteresis Research Articles

Effect of magnetomechanical hysteresis on the field-induced oscillations of particles in a magnetoactive elastomer.

A model is proposed for mesoscopic dynamics of a magnetoactive elastomer (MAE). The elementary cell comprises two spherical linearly magnetizing particles embedded in an elastoviscous medium of the Kelvin type. The forced oscillations of this system induced by an ac field are studied. Under a static field, this system is prone to bistability that entails the magnetomechanical hysteresis: being initially separated by a finite distance, the particles move jumplike to a tight contact. The initial configuration is restored under a field that is lower than that of its onset. It is shown that in the oscillatory regime, depending on the material parameters of the system and the characteristics of the oscillating field, the pair may display steady cycles of several types. Upon enhancing the frequency, the occurrence of the particle contact may be blocked or, on the contrary, they might be "quenched" in the vicinity of each other. The behavior of the pair at a high frequency is analyzed. Estimations are given for the energy dissipation caused by the hysteretic regimes of the particle oscillations.

Magneto-mechanical hysteresis damping mechanism in dual-phase iron-based alloy with zero magnetostriction

Magneto-mechanical hysteresis damping (MMHD) is usually positively correlated with their measured magnetostriction, but this correlation becomes ambiguous in negative magnetostriction and multiphase materials. This work found that even if saturated magnetostriction of Co-20Fe alloy is zero, its MMHD value can still be as high as 0.015. Analysis revealed that the MMHD correlates with phase percentages and the absolute parallel magnetostriction values of phases. In multiphase alloys, measured magnetostriction cannot be directly used to assess damping. High nonmagnetic damping in Co-15Fe alloy with fcc structure is due to distributed misfit dislocations. This research sheds light on damping mechanisms in multiphase ferromagnetic alloys.

Twinning damping interface design and synergistic internal friction behavior in FeMnCrCo high-entropy alloys

Vibration and noise reduction has always been important problem to be solved in the fields of rail transit, aerospace, marine engineering, and so on. In this paper, a novel Fe65-XMn20Cr15CoX (X = 5, 10, 15, 20) dual-phase high-entropy damping alloy with excellent properties were prepared by vacuum melting. The dependence of the alloy damping behavior on the twin interface, magnetic properties and phase interface was emphatically analysed. The effects of Co content on its microstructure, damping behavior and magnetic properties were investigated. The results show that with the increase of Co content, ε martensite gradually transforms to γ austenite, and the number of twins increases gradually. The peak damping (Q−1) increased from 0.0442 to 0.0595, an increase of 34.6%. The coupled effects of magneto-mechanical hysteresis, twin interface motion, and phase interface motion provide the alloy's excellent damping properties. The alloy has a higher damping internal friction peak of around 200 °C, which is due to the phase transition from ε to γ at the temperature. By adjusting the Co content, the phase content and twinning and other microstructures of the alloy can be regulated, and multiple damping mechanisms can be coupled to achieve higher damping performance.

Attenuation of magnetomechanical hysteresis effect by excessively annealing Fe-16Cr-2.5 ∼ 3.5Mo damping alloys

Ferromagnetic Fe-Cr alloys can be used to reduce unwanted noise and vibrations because of their high damping capacity which is attributed to the irreversible magnetic domain-wall movement. However, excessive annealing usually causes an obvious drop of damping capacity of the alloys. In the present study, the magnetomechanical hysteresis effect (MMHE) is investigated by measuring magnetostriction coefficients of the annealed Fe-16Cr-2.5 ∼ 3.5Mo alloys. It is found that the annealing more than 1 h at 900℃ causes the attenuation of MMHE. The higher Mo concentration restrains the MMHE attenuation and the damping decline due to the MMHE attenuation. The research could help us to better understand the alloying role in the damping mechanism of Fe-Cr based alloys.

FORC analysis of magnetically soft microparticles embedded in a polymeric elastic environment

First-order reversal curve (FORC) analysis allows one to investigate composite magnetic materials by decomposing the magnetic response of a whole sample into individual responses of the elementary objects comprising the sample. In this work, we apply this technique to analysing silicone elastomer composites reinforced with ferromagnetic microparticles possessing low intrinsic coercivity. Even though the material of such particles does not demonstrate significant magnetic hysteresis, the soft matrix of the elastomers allows for the translational mobility of the particles and enables their magnetomechanical hysteresis which renders into a wasp-waisted major magnetization loop of the whole sample. It is demonstrated that the FORC diagrams of the composites contain characteristic wing features arising from the collective hysteretic magnetization of the magnetically soft (MS) particles. The influence of the matrix elasticity and particle concentration on the shape of the wing feature is investigated, and an approach to interpreting experimental FORC diagrams of the MS magnetoactive elastomers is proposed. The experimental data are in qualitative agreement with the results of the simulation of the particle magnetization process obtained using a model comprised of two MS particles embedded in an elastic environment.

Modeling of Magneto-Mechanical Damping in Ferromagnetic Alloys: a Brief Review

This review is devoted to the analysis of three components of magneto-mechanical damping (MMD), namely, macroeddy, microeddy, and hysteresis components, in ferromagnetic alloys. Theoretical models and equations for all three components of the MMD are discussed. The application of the classical theory of micro- and macroeddy MMD to determine the influence of the frequency of cyclic external mechanical load on the damping ability of the material is shown. A discussion on the role of various factors, such as temperature, strain amplitude, vibration frequency, and external magnetic field, on the magnitude of the MMD is provided.

Synergistic damping effect mechanism of magneto-mechanical hysteresis and dislocations energy dissipation in FeMnCrCo high entropy alloys

The Fe65-xMn20Cr15Cox (x = 0, 5, 10, 15) high entropy alloys (HEAs) were prepared by mechanical alloying (MA) and spark plasma sintering (SPS). The effects of the configurational entropy on the microstructure, magnetic properties, and damping behaviors were investigated in this paper. As the Co content increased, the configurational entropy of the HEAs was increased from 0.88R to 1.23R, the magnetology performance was reduced significantly, but the peak of internal friction (IF) Q-1 increased monotonously. The maximum internal friction (IF) Q-1max achieved 0.073 when 15 at% Co element was added. With the configurational entropy increasing, in addition to the ferromagnetic damping mechanism, the dislocation damping mechanism was introduced in the HEAs. The synergistic effect of magneto-mechanical hysteresis and dislocation energy dissipation ensured the FeMnCrCo HEAs maintained high damping performance in a wide strain amplitude. Through the regulation of the microstructure, the possibility of application of the damping alloy under extreme conditions can be expanded.

Attenuation of Magnetomechanical Hysteresis by Excessively Annealing Fe-16Cr-2.5~3.5Mo Damping Alloys

Attenuation of Magnetomechanical Hysteresis by Excessively Annealing Fe-16Cr-2.5~3.5Mo Damping Alloys

High damping in Fe-Ga-La alloys: Phenomenological model for magneto-mechanical hysteresis damping and experiment

Ferromagnetic high damping (FHA) alloys with a wide temperature range from -150 °C to 300 °C have unique application value in extreme environments. In the present work, the damping behaviors of Fe-21Ga-xLa (x = 0.12 wt.%, 0.24 wt.%, 0.47 wt.%, 1.18 wt.%, and 2.33 wt.%La) alloys have been studied in detail, and a new phenomenological model has been proposed. With the increase of La content, the Laves phase (LaGa2) in the matrix increases gradually, and the resistance opposing the domain movement increases as well. Combined with the results of synchrotron radiation X-ray diffraction, neutron diffraction, and magnetic domain observation, the resistance mainly comes from three parts: the average stress related to the lattice distortion of the matrix, the average stress related to the increasing area energy of domain walls (DWs), and the average stress related to the increasing demagnetization energy induced by the Laves phase. Different from the traditional method of reducing internal stress through annealing to improve the damping capacity, the proper internal stress barriers are necessary to Barkhausen jumps to dissipate energy. Therefore, proper doping to balance resistance and mobility of DWs is a reliable way to improve damping capacity. Meanwhile, for Fe-Al and Fe-Cr based Alloys, the new model also has a good fitting effect. This study provides a theoretical and experimental reference for improving the functional properties of ferromagnetic alloys.

Higher damping capacity induced by negative magnetostriction of Fe-16Cr-2.5Mo-0∼0.2V alloys

High damping Fe–Cr alloys attract much attention for their higher damping capacity. So far, the alloying technique is of importance to achieving a higher damping capacity of the alloys; however, the effect of vanadium on the magnetomechanical hysteresis effect (MMHE) is unclear. Herein, we observed the optical microstructure and domain structures by using an optical microscope. The damping behavior was measured by an inverted torsion pendulum. The magnetostriction coefficient was measured by XRD, and the magnetic properties were measured by a vibration sample magnetometer. We demonstrate that the crystal volume of the Fe–16Cr-2.5Mo based alloys contracts due to the addition of V. In addition, the V element results in a negative volume magnetostriction of the alloys. Their ferromagnetic damping value depends on the absolute value of saturation magnetostriction coefficient, whether the saturation magnetostriction coefficient is positive or negative.

Effect of mesoscopic magnetomechanical hysteresis on magnetization curves and first-order reversal curve diagrams of magnetoactive elastomers

Magnetoactive elastomers may display magnetic hysteresis, even if they are filled only with magnetically soft particles. In this work we discuss application of the first-order reversal curve (FORC) analysis to identify and study hysteresis of that kind. To obtain theoretical magnetization curves and FORC diagrams for the composites in question, a simple model comprising two magnetically soft particles embedded in an elastic environment is proposed. Elucidation of the features present in FORC diagrams is conducted using computer simulation. Despite the simplicity of the model, it allows one to explain the origin of diagonal ridge patterns, which turn up in the FORC diagrams of elastomer composites with magnetically soft filler, and to quantify the experimental results. As the ridge pattern of the diagrams is inherently exclusive to such types of materials, it could be useful for their diagnostics.

A novel method for dynamic characterization of angular displacement-dependent viscoelastic properties of magnetorheological elastomer under torsional loading conditions

The dynamic properties of magnetorheological elastomers are predominantly affected by variation in the input displacements. The displacement-dependent characteristics have been extensively studied under lateral shear, but the property variations under torsional shear have not been explored. The present study focuses on developing a novel method to study the influence of angular displacement on the dynamic properties of magnetorheological elastomers under torsional loading conditions. The experimental setup is developed according to the ISO 10846-2 standard to evaluate the variations in the dynamic torsional stiffness and loss factor. Experiments are conducted for input angular displacements ranging from 0.002 to 0.016 rad for an input frequency between 10 and 30 Hz. Results highlight the effectiveness of the developed method in capturing the rheological properties under torsion. Variations in the dynamic torsional stiffness suggest the dominant behaviour of the input angular displacement. The bound rubber theory is used to interpret the angular displacement dependent variations on the torsional stiffness. Further, the effect of input frequency and magnetic field on the dynamic torsional stiffness is also examined. It is also observed that the damping capacity of the MRE is dependent on the angular displacement and the dissipation capacity of the elastomer is evaluated in terms of loss factor. Results indicate a significant contribution of the interfacial damping over the intrinsic and magneto-mechanical hysteresis damping.

Study of magnetic field distribution in anisotropic single twin-boundary magnetic shape memory (MSM) element in actuators

Magnetic shape memory effect exhibited by certain alloys at room temperature is known for almost 20 years. The most studied MSM alloys are Ni-Mn-Ga alloys which exhibit up to 12% magnetic field-induced strain (change in shape) depending on microstructure. A multibillion cycle operation without malfunction along with their “smart” properties make them very promising for application in electromagnetic (EM) actuators and sensors. However, considerable twinning stress of MSM crystals resulting in magneto-mechanical hysteresis decreases the efficiency and output force of MSM actuators. Whereas twinning stress of conventional MSM crystals has been significantly decreased over the years, novel crystals with Type II twin boundaries (TBs) possess even lower twinning stress. Unfortunately, the microstructure of MSM crystals with very low twinning stress tends to be unstable leading to their rapid crack growth. Whilst this phenomenon has been studied experimentally, the magnetic field distribution in anisotropic single twin-boundary MSM elements has not been considered yet. This paper analyses the magnetic field distribution in two-variant single twin-boundary MSM elements and discusses its effects on magnetic field-induced stress acting on the twin boundary.

Elastic properties of magnetorheological elastomer: description with the two-particle mesoscopic model

A pair of magnetizable solid particles embedded in a cylinder made of high-elasticity material is considered as a model of a mesoscopic structure element of a magnetorheological elastomer. An applied magnetic field induces ponderomotive interaction of the particles making them to move relative to one another so as to balance the counteracting magnetic and elastic forces. In a certain parameter range, the system exhibits bistability due to which under the increase / decrease of the field, the interparticle distance changes in a hysteretic manner. This behavior has a significant effect on the ability of the mesoscopic element to resist external load. Using the developed two-particle model prone to the magnetomechanical hysteresis, we extend it to the case of a virtually macroscopic sample presenting the latter as a superposition of such elements with distributed interparticle distances. In spite of its simplicity, this scheme in a generally correct way describes the field-induced changes of the internal structure and elastic modulus of the magnetorheological composites.

Mesoscopic magnetomechanical hysteresis in a magnetorheological elastomer.

Field-induced magnetostatic interaction in a pair of identical particles made of a magnetically soft ferromagnet is studied. It is shown that due to saturation of the ferromagnet magnetization, this case differs significantly from the (super)paramagnetic one. A numerical solution is given, discussed, and compared with that provided by a simpler model (nonlinear mutual dipoles). We show that for multidomain ferromagnetic particles embedded in an elastomer matrix, as for paramagnetic ones in the same environment, pair clusters may form or break by a hysteresis scenario. However, the magnetization saturation brings in important features to this effect. First, the bistability state and the hysteresis take place only in a limited region of the material parameters of the system. Second, along with the hysteresis jumps occurring under the sole influence of the field, the "latent" hysteresis is possible which realizes only if the action of the field is combined with some additional (nonmagnetic) external factor. The obtained conditions, when used to assess the possibility of clustering in real magnetorheological polymers, infer an important role of mesoscopic magnetomechanical hysteresis for the macroscopic properties of these composites.

Modeling of particle interactions in magnetorheological elastomers

The interaction between two particles made of an isotropic linearly polarizable magnetic material and embedded in an elastomer matrix is studied. In this case, when an external field is imposed, the magnetic attraction of the particles, contrary to point dipoles, is almost wraparound. The exact solution of the magnetic problem in the linear polarization case, although existing, is not practical; to circumvent its use, an interpolation formula is proposed. One more interpolation expression is developed for the resistance of the elastic matrix to the field-induced particle displacements. Minimization of the total energy of the pair reveals its configurational bistability in a certain field range. One of the possible equilibrium states corresponds to the particles dwelling at a distance, the other—to their collapse in a tight dimer. This mesoscopic bistability causes magnetomechanical hysteresis which has important implications for the macroscopic behavior of magnetorheological elastomers.

On relationship between annealing treatment and magnetostriction behavior of Fe–16Cr–2.5Mo damping alloy

Abstract The damping capacity of Fe–16Cr–2.5Mo damping alloy was analyzed using a cantilever device. The magnetostriction property was measured using an improved Michelson interferometer. The domain morphology was optically observed using a magneto-fluid. Magnetomechanical Hysteresis Effect (MMHE) was discussed by analyzing the relationship between the magnetostriction performance and the annealing process of the alloy. The results show that the variation of saturate magnetostriction coefficient is quite consistent with that of the damping capacity of the annealed samples. With the local internal stress widely distributing in the annealed alloy, both the domain’s mobility and their structure vary with the increasing annealing temperature and time. The local internal stress not only pins the domain mobility but also makes the domain structure disorder. The domain size and the number of 90° magnetic domains are responsible for the highest damping capacity of the sample annealed at 900 °C for 1 h. However, with the prolonged annealing time, the number of 90° domain decreases sharply and more heterogeneous domains appears in the alloy. The spike domains can also pin domain-walls.

Fully coupled modeling of magneto-mechanical hysteresis through ‘thermodynamic’ compatibility

The paper proposes a phenomenological model for magneto-elastic interactions in materials with hysteresis, where both mechanical and magnetic variables are fully coupled. The approach allows one to provide a tool for the description of the energy conversion mechanism in the presence of losses, for example, in harvesting devices. The present approach takes into account exchange between mechanical and magnetic energies, as well as dissipation due to hysteresis phenomena. Using the concept of hysteresis potentials, it is shown that the model is consistent with classical nonequilibrium thermodynamics. The effectiveness of the approach is demonstrated by comparison with experimental data.

Silicon carbide‐strengthened magnetorheological elastomer: Preparation and mechanical property

A novel silicon carbide (SiC)‐strengthened magnetorheological elastomers (MREs) was developed to enhance its viscoelastic performance. The influences of the size and weight content of the SiC particles on the viscoelastic performance of the MREs were systematically studied. The shear storage modulus, damping property, and magnetorheological effects were analyzed to evaluate their dynamic properties. Under optimum condition, the initial storage modulus (G0) of the MRE‐0.06‐SiC‐3 (SiC weight content 3.2 wt%, mean diameter 0.06 μm) is about 2.16 times larger than the MRE‐0.06‐SiC‐0 (nondoped MRE), whereas the magnetorheological effect was almost kept constant. In addition, the damping properties of the as‐prepared MREs which were obtained from the intrinsic damping, the magnetomechanical hysteresis, and the interface damping were also analyzed. These results provided a meaningful method for developing MREs with controllable storage modulus and damping capacity. POLYM. ENG. SCI., 53:2615–2623, 2013. © 2013 Society of Plastics Engineers

Magnetomechanical behavior for assessment of fatigue process in ferromagnetic steel

In this work, the change of magnetization as a function of applied stress has been investigated for test specimens of AISI 1018 steel. The various stages of fatigue damage process are characterized by the magnetomechanical measurements recorded by an APS 428D fluxgate magnetometer. Of great significance is the fact that the stress-magnetic field hysteresis loop area changes systematically with the progression of fatigue. The magnetomechanical hysteresis demonstrates conspicuous changes in the initial stage of fatigue loading, then reverts to a relatively stable phase, and finally, drastic variations appear again as the cyclic loadings approach terminal failure. This work demonstrated that it is possible to correlate the progress of fatigue in ferromagnetic steels with the nondestructive evaluation technique of the magnetomechanical effect.