Giant Magnetostriction Research Articles

Complexification-Averaging Analysis on a Giant Magnetostrictive Harvester Integrated With a Nonlinear Energy Sink

The present study aims to investigate the steady-state response regimes of a device comprising a nonlinear energy sink (NES) and a giant magnetostrictive energy harvester utilizing analytical approximation. The complexification-averaging (CX-A) technique is generalized to systems defined by differential algebraic equations (DAEs). The amplitude-frequency responses are compared with numerical simulations for validation purposes. The tensile and compressive stresses of giant magnetostrictive material (GMM) are checked to ensure that the material functions properly. The energy harvested is calculated and the comparison of transmissibility of the apparatus with and without NES–GMM is exhibited to reveal the performance of vibration mitigation. Then, the stability and bifurcations are examined. The outcome demonstrates that the steady-state periodic solutions of the system undergo saddle-node (SN) bifurcation at a certain set of parameters. In the meantime, no Hopf bifurcation is observed. The introduction of NES and GMM for vibration reduction and energy harvesting brings about geometric nonlinearity and material nonlinearity. By computing both the responses of the primary system equipped with the NES only and the NES–GMM, it is indicated that the added GMM can dramatically modify the steady-state dynamics. A further optimization with respect to the cubic stiffness, the damper of NES, and the amplitude of excitation is conducted, respectively. The boundary where the giant magnetostrictive energy harvester is out of work is pointed out as well during the process of optimizing.

Correlation between magnetostriction and magnetic structure in pseudobinary compounds Tb(Co1-xFex)2

Giant low-field magnetostriction has been achieved in pseudobinary Laves phase compounds RR’T2 (R and R’: rare earth elements; T: transition metal elements) around the ferromagnetic - ferromagnetic (ferro.-ferro.) transition temperature. Evolution of the magnetic structure across such transition requires comprehensive investigation. In this work, pseudobinary system Tb(Co1-xFex)2 is selected to investigate the evolution of local magnetic moment, for which two end terminals TbCo2 and TbFe2 possess the rhombohedral (R) structure at the ferromagnetic state but with different magnetic ordering temperatures (TC). Magnetometry measurements reveal that a composition independent ferromagnetic - ferromagnetic transition occurs at ∼100 K despite the increased Curie temperature TC with raised Fe concentration in the Tb(Co1-xFex)2. Synchrotron XRD data reveal that both the lattice parameter and the lattice strain along the <111> direction are abnormally temperature dependent, accompanied with experimentally observed magnetostriction abnormality at 100 K. In-situ neutron powder diffraction (NPD) results show that the local magnetic moments of T2 (9e site) atoms are also abnormally temperature dependent, which is larger at 100 K than that at a lower temperature 50 K. Such findings indicate close correlations between the magnetic structure and the magnetostrictive effect in the pseudobinary RT2 compounds.

Local inhomogeneous structural origin of giant magnetostriction in Fe-Ga alloys

Melt-spun ribbons and single crystal plates of Fe83Ga17 alloys were studied at both nano-scale and atomic-scale to investigate the structure origin of their giant magnetostriction. The presence of nano-precipitates in the melt-spun ribbons was verified using synchrotron x-ray diffraction and was validated by small angle scattering experiment. The nano-precipitates were found to be inhomogeneously distributed within the ribbons, as peak splitting clearly observed in the diffraction patterns disappeared into broad peaks when the synchrotron beam was focused onto different parts of the same sample. Further analysis using x-ray diffuse scattering and extended x-ray absorption fine structure indicates the existence of short-range ordering (SRO) Ga-Ga pairs along the (001) direction in both the ribbon and single-crystal alloys. All experimental evidence suggests that this modified D03-type SRO leads to both a short-range lattice strain and a long-range symmetry breaking tetragonal distortion of the A2 lattice. This gives rise to giant magnetostriction in the Fe-Ga alloys. In the melt-spun ribbons, the Ga-Ga pairs can aggregate into nano-sized precipitates under fast cooling and enhance the magnetostriction further.

Design of new giant magnetostrictive structures for double-nut ball screw pre-tightening

As a high-precision drive mechanism, double-nut ball screw is widely used in machining and manufacturing field. A pre-tightening structure added to the double-nut ball screw may reduce the axial clearance between nuts and screw, thus to increase transmission accuracy. The present commonly used pre-tightening structure cannot realize automatic regulation of pre-tightening force, so three new structures are designed in this article to achieve timely adjustment of pre-tightening force, namely the pre-tightening structure composed of hollow cylindrical GMM (Giant Magnetostrictive Material: Terfenol-D), the pre-tightening structure composed of three discrete Terfenol-D rods and the giant magnetostrictive pre-tightening structure with hinge-levers. After analyzing their structure characteristics and electromagnetic coupling relations, it is found that the giant magnetostrictive pre-tightening structure with hinge-levers is superior to the other two in performance. Electromagnetic coupling experiment result of this structure shows that it meets the pre-tightening requirements of double-nut ball screw, and can adjust the pre-tightening force by adjusting the electric current.

Measurement of the Length of Installed Rock Bolt Based on Stress Wave Reflection by Using a Giant Magnetostrictive (GMS) Actuator and a PZT Sensor.

Rock bolts, as a type of reinforcing element, are widely adopted in underground excavations and civil engineering structures. Given the importance of rock bolts, the research outlined in this paper attempts to develop a portable non-destructive evaluation method for assessing the length of installed rock bolts for inspection purposes. Traditionally, piezoelectric elements or hammer impacts were used to perform non-destructive evaluation of rock bolts. However, such methods suffered from many major issues, such as the weak energy generated and the requirement for permanent installation for piezoelectric elements, and the inconsistency of wave generation for hammer impact. In this paper, we proposed a portable device for the non-destructive evaluation of rock bolt conditions based on a giant magnetostrictive (GMS) actuator. The GMS actuator generates enough energy to ensure multiple reflections of the stress waves along the rock bolt and a lead zirconate titantate (PZT) sensor is used to detect the reflected waves. A new integrated procedure that involves correlation analysis, wavelet denoising, and Hilbert transform was proposed to process the multiple reflection signals to determine the length of an installed rock bolt. The experimental results from a lab test and field tests showed that, by analyzing the instant phase of the periodic reflections of the stress wave generated by the GMS transducer, the length of an embedded rock bolt can be accurately determined.

NiFe2 and its nitride γ-NiFe2N derived from NiFe2O4: Magnetostriction, thermal expansion, resistivity and corrosion resistance

γ-NiFe2N with the face centered cubic symmetry, rather than the hexagonal symmetric ɛ-NiFe2N in previous reports, was synthesized by treating NiFe2 alloy in an ammonia atmosphere. Compared with the NiFe2 sample, the γ-NiFe2N exhibited the strong ferromagnetism, giant magnetostriction, high resistivity and good corrosion resistance. The unique properties of γ-NiFe2N expand its applications. Besides, as a magnetostriction material, γ-NiFe2N does not contain any resource-critical rare-earth elements and it is over ten times lower cost than the rare-earth doped Galfenol or Terfenol-D alloys because Ga, Tb or Dy is very expensive.

Giant isotropic magnetostriction in NaZn13-type LaFe13−xAlx compounds

The unusual low-temperature magnetostrictive property is of fundamental interest due to significant applications in rapidly developing cryogenic engineering. Here, we report a giant isotropic magnetostriction (λ = 1500 ppm, ω = 4500 ppm) over a wide temperature range (∼210 K), and the saturated volume magnetostriction can be up to 8400 ppm in cubic NaZn13-type LaFe13−xAlx compounds by optimizing the chemical composition. The large magnetostrictive effect often occurs in ferromagnetic materials. However, we discovered that the magnetic-field-induced volume expansion originates from the change of lattice parameters across the first-order transition from the low-volume antiferromagnetic ground state to the high-volume ferromagnetic state. Moreover, the magnetostrictive materials show an excellent zero thermal expansion (ZTE) property, which guarantees their reliability and stability operating at various temperatures. The present study suggests potential applications of La(Fe, Al)13-based compounds as ZTE and magnetostrictive dual-function materials in cryogenic engineering.

A Study on Practical Possibility of Optimization Using Stationary Point Theory in Dynamic Absorber Using Giant Magnetostrictive Material

A Study on Practical Possibility of Optimization Using Stationary Point Theory in Dynamic Absorber Using Giant Magnetostrictive Material

Specific features of the states of cobalt fluoride in the vicinity of the critical field

The state of cobalt fluoride in the vicinity of the critical value H c of a longitudinal magnetic field H, in which the magnetic subsystem of a CoF2 crystal with a strong Dzyaloshinskii interaction is transformed from the antiferromagnetic phase into the canted phase, has been investigated taking into account the increasing number of experimental studies related to the use of cobalt fluoride. It has been found that, despite the unusually high magnetic anisotropy of the crystal, the state of the magnetic subsystem at H = H c is extremely sensitive to a small deviation of the vector H from the C 4 axis. Another feature is that the high sensitivity disappears with an increase or decrease in the magnetic field by only a few thousandths of H c . The results of the investigations performed in this work are applicable to magnetically ordered crystals FeF3 and Cu2OSeO3, which, as well as the CoF2 crystals, are characterized by a strong Dzyaloshinskii interaction and a significant magnetic anisotropy. The revealed anomaly in the reduction of the effective magnetic anisotropy is of interest in connection with numerous attempts to decrease the magnetic anisotropy in crystals with giant magnetostriction, which are necessary for the use as sensors and vibrators.

Reversible magnetocaloric effect in materials with first order phase transitions in cyclic magnetic fields: Fe48Rh52 and Sm0.6Sr0.4MnO3

The magnetocaloric effect (MCE) in an Fe48Rh52 alloy and Sm0.6Sr0.4MnO3 manganite was studied in cyclic magnetic fields. The adiabatic temperature change in the Fe48Rh52 alloy for a magnetic field change (ΔB) of 8 T and a frequency (f) of 0.13 Hz reaches the highest value of (ΔTad) of −20.2 K at 298 K. The magnitude of the MCE in Sm0.6Sr0.4MnO3 reaches ΔTad = 6.1 K at the same magnetic field change at 143 K. The temperature regions, where a strong MCE is exhibited in an alternating magnetic field, are bounded in both compounds. In the case of the Fe48Rh52 alloy, the temperature range for this phenomenon is bounded above by the ferromagnetic to antiferromagnetic transition temperature in the zero field condition during cooling. In the case of the Sm0.6Sr0.4MnO3 manganite, the temperature range for the MCE is bounded below by the ferromagnetic-paramagnetic transition temperature in zero field during heating. The presence of these phase boundaries is a consequence of the existence of areas of irreversible magnetic-field-induced phase transitions. It is found that the effect of long-term action of thousands of cycles of magnetization/demagnetization degrades the magnetocaloric properties of the Fe48Rh52 alloy. This can be explained by the gradual decrease in the size of the ferromagnetic domains and increasing role of the domain walls due to giant magnetostriction at the ferromagnetic to antiferromagnetic transition temperature. The initial magnetocaloric properties can be restored by heating of the material above their Curie temperature.

A bilateral capacitance compensation method for giant magnetostriction ultrasonic processing system

To improve the capacity and reliability of a rotary ultrasonic machining system, a novel giant magnetostriction ultrasonic processing system (GMUPS) was designed. By using the equivalent circuit model, an optimal compensation model of the GMUPS, with and without a rotary transformer, was proposed. Considering the distributed capacitance of the coil at high frequency, the method of impedance analysis was applied to determine a feasible optimal compensation. To identify the optimal compensation parameters, the characteristics of the GMUPS were studied, including its primary and secondary currents, resonant frequency, and vibration amplitude. The results of the vibration amplitude test demonstrated that impedance analysis was a feasible way to determine the optimal compensation capacitance. The compensation circuit greatly affected the magnitude of the vibration output of the GMUPS, while it did not affect the amplitude-current sensitivity or resonant frequency of the GMUPS. By optimizing the compensation circuit, the impedance of the GMUPS was obviously reduced and the vibration amplitude was maximized. In addition, these results show that impedance analysis can produce a series of relatively optimal compensation capacitances, which makes it greatly useful for adjusting the compensation capacitance as the primary or secondary compensation capacitance deviates from its optimal value.

Fiber-Optic Current Sensor Head Based on the Giant Magnetostrictive Materials

A current sensing method based on giant magnetostrictive material (GMM) and fiber Bragg grating (FBG) was proposed, which not only combines the advantages of FBG such as wavelength encoding, compatibility with fiber and distributed measurement system realization, but also the advantages of GMM as large flexible coefficient, high electromechanical coupling coefficient and short response time. The minimal residual method was put forward to effectively identify the Jiles-Atherton model parameters of ferro-magnetic material. The parameters of the giant magnetostrictive ( Terfenol-D bar ) and the Jiles-Atherton model was established and optimized by using the Mathematica software. Then the optical fiber current test system with ferromagnetic loop was set up to investigate the current sensing properties of the sensor. The relationship between current excitation and GMM-FBG reflected wavelength was obtained, which provides basic support for further current sensing experiment research.

Improved magnetostriction of Fe83Ga17 ribbons doped with Sm

In order to demonstrate that light rare-earth (RE) dopants with strong magnetocrystalline anisotropy, whose net moment couples are antiparallel to those of iron, can also induce giant magnetostriction in Gafenol, a light RE element Sm was selected as the third element to dope into Fe83Ga17 alloy. (Fe0.83Ga0.17)100−x Sm x (0 ≤ x ≤ 0.42) ribbons were prepared by melt spinning. The increase of the lattice parameters and saturation magnetization indicates that some Sm atoms enter the A2 matrix substitutionally. Doping the Fe83Ga17 ribbons with the light RE Sm element drastically improves the magnetostriction. Perpendicular magnetostriction value of λ ⊥ = −5 × 10−4 is achieved in (Fe0.83Ga0.17)99.75Sm0.25. It is confirmed that the stronger local magnetocrystalline anisotropy induces larger enhanced magnetostrictions. The greatly enhanced magnetostriction is somehow related to the local microstrains induced by the RE dopants. It is likely that the RE-induced defects in the (Fe0.83Ga0.17)100−x RE x ribbons function in the similar way as the Ga–Ga pair defects in the undoped Fe–Ga alloys.

Enhanced magnetoelastic effect in Laves (Tb,Dy)Fe2 alloys with the joint introduction of Pr and Nd

The structural and magnetoelastic properties of (Tb0.3Dy0.7)1−x(Pr0.5Nd0.5)xFe1.93 (0 ≤ x ≤ 0.20) polycrystalline alloys have been investigated by means of X-ray diffraction (XRD), a vibrating sample magnetometer and a standard strain gauge technique. A single (Tb,Dy,Pr,Nd)Fe2 Laves phase with a cubic MgCu2-type structure is formed when x ≤ 0.12, while a small amount of impurities appear when x ≥ 0.15. The easy magnetization direction at room temperature is detected toward axis. The analysis of XRD, magnetization and magnetostriction shows that the Pr and Nd elements joint introduction into (Tb,Dy)Fe2 system can reduce the magnetocrystalline anisotropy and improve the magnetoelastic properties. The (Tb0.3Dy0.7)0.88(Pr0.5Nd0.5)0.12Fe1.93 alloy exhibits a high low-field magnetostriction λa (~314 ppm/1 kOe), a large spontaneous magnetostriction coefficient λ111 (~1710 ppm), a giant saturation magnetostriction λS (~1060 ppm) and the low magnetocrystalline anisotropy at room temperature, and may make it a promising candidate for magnetostriction applications.

Fracture Behavior of Cracked Giant Magnetostrictive Materials in Three‐Point Bending under Magnetic Fields: Strain Energy Density Criterion

In this paper, the fracture behavior of cracked giant magnetostrictive materials has been investigated both numerically and experimentally. Works in literature have been revisited, focusing on iron and rare‐earth alloys, such as Terfenol‐D. Three‐point bending tests have been carried out on precracked specimens and the fracture loads have been measured in the presence and absence of a magnetic field. Recent studies on local stress fields in proximity of crack tips have shown that the Strain Energy Density (SED) can be a robust parameter in the brittle fracture assessment. Coupled‐field finite element analyses have then been performed and the effect of the magnetic field on Terfenol‐D fracture resistance has been discussed in terms of Energy Release Rate and averaged SED.

Multifunctional phenomena in sublimed dysprosium in high magnetic fields: The magnetocaloric effect and magnetostriction

With the use of sublimed dysprosium having a controllable impurity composition, two physical functional phenomena induced by a magnetic field are studied: magnetostriction and the magnetocaloric effect, which is estimated by independent direct and indirect methods. A giant magnetostriction value at the “order–order” magnetic phase transition and a large magnetocaloric effect in high magnetic fields at the “order–disorder” transition are shown. Both phenomena are discussed in relation to the complex field and temperature behavior of metallic-dysprosium magnetization, the measurement of which is carried out in wide intervals of temperature and magnetic fields (to 14 T).

Giant heterogeneous magnetostriction in Fe–Ga alloys: Effect of trace element doping

Enhanced magnetostriction in iron-rich Fe–Ga alloys has been attributed to a heterogeneous nanostructure with tetragonal inclusions, although direct experimental evidence for their structure was lacking. Here we use transmission electron microscopy to show that melt-spun, (001) textured Fe83Ga17 ribbons contain 3 nm inclusions with c-axis Ga–Ga pairs aligned in a tetragonal L60-type structure; the induced tetragonality of the entire A2 matrix is observed directly by synchrotron X-ray diffraction. Trace doping with 0.2 atomic % nonmagnetic elements such as La or Pb increases the magnetocrystalline anisotropy and greatly enhances the magnetostriction. Rare-earth dopants from La to Lu produce a quarter-shell variation of the magnetic anisotropy; the crystal field parameter A20 is determined to be −15 Ka0−2. The best trace dopants are the light rare earths Ce and Pr that give a transverse magnetostriction of up to −800 ppm, as these elements soften the tetragonal modulus via their crystal field interaction. A new model is proposed to explain nanoheterogeneous magnetostriction, where the Ga–Ga pairs remain fixed, but the tetragonal axis of the matrix can be realigned in a magnetic field by a series of small deformations of the A2 matrix. These results signal a new approach to creating highly-magnetostrictive materials.

Effects of the Interfacial Transition on the Giant Magnetostriction in a Superconductor–Substrate Structure

This study concerns the effects of the interfacial transition on the giant magnetostriction in superconductor-substrate structures under alternating magnetic field. The magnetostriction is induced in terms of internal force arising from flux pinning. The superconductor E-J constitutive law is characterized by H-formulation that can calculate the current distribution and electromagnetic fields as well as the magnetization of the high-temperature superconductor. Different interfacial transition functions and physical parameters as well as geometrical parameters are introduced to analyze the magnetostriction by the finite-element method. Results show that interfacial transitions have significant effects on the magnetostriction.

Variation of Magnetoelectric Coefficient with Volume Fraction of Piezoelectric Phase in Pb(Mg1/3Nb2/3)O3-PbTiO3/FeCoV Laminate Composite

Soft magnetic material FeCoV is sensitive to magnetic field and its cost is lower than giant magnetostriction materials (Terfenol-D et al.). In the present investigation Pb (Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) with different thickness and FeCoV laminate with 0.8mm thickness were assembled into layer structure to study the effect of the PMN-PT volume fraction on the magnetoelectric coefficient of PMN-PT/FeCoV laminate composites. The ME coefficients and voltages have been characterized in the longitudinally magnetized and transversely polarized mode. The measurement was conducted under a static magnetic field superimposed with an alternating magnetic field. The influences of the static and the alternating field strength were discussed. The peak ME coefficient was obtained at 430 Oe. With the volume fraction of PMN-PT increased, the ME coefficient decreased within the experiment fraction. It can be explained by the module of M.I.Bichurin. A linear relationship was observed between the magnetoelectric voltage and the alternating field strength under a static field of 400 Oe. The ME voltage decreased when the PMN-PT volume fraction increased in the experiment fraction.

Giant magnetothermal conductivity and magnetostriction effect in the charge ordered Nd0.8Na0.2MnO3 compound

We present results on resistivity (ρ), magnetization (M), thermal conductivity (κ), magnetostriction and specific heat (Cp) of the charge-orbital ordered antiferromagnetic Nd0.8Na0.2MnO3 compound. Magnetic-field–induced antiferromagnetic/charge-orbital ordered insulating to ferromagnetic metallic transition leads to giant magnetothermal conductivity and magnetostriction effect. The low-temperature irreversibility behavior in ρ, M, κ and due to field cycling together with a striking similarity among the field and temperature dependence of these parameters manifest the presence of a strong and complex spin-charge-lattice coupling in this compound. The giant magnetothermal conductivity is attributed mainly to the suppression of phonon scattering due to the destabilization of spin fluctuations and static/dynamic Jahn-Teller distortion by the application of magnetic field.