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This paper proposes a multilevel three-dimensional constitutive model based on a microscopically phenomenological approach from the domain rotation mechanism, which is a fully coupled self-consistent homogenization scheme considering the interactions between elastic–inelastic strain and hysteresis. Considering the interactions among magnetic domains, grains, polycrystalline complexes, and macroscopic phenomenology, we predict the nonlinear magnetostrictive response of Terfenol-D under different types of external force loads and magnetic excitations in various thermal environments involving multi-fields of coupled magnetic, elastic, thermal, and mechanical phenomena. The average values of the mechanical bulk strains for different magnetization states are obtained at the grain scale utilizing Boltzmann functions and a self-consistent homogenization scheme. A Taylor series expansion of the Gibbs function concerning the field variables and an adapted Jiles–Atherton model are used to construct the hysteresis coupled constitutive relations at the macroscopic scale. The results associated with the experiments show that the established model can reasonably predict the magnetostrictive response under different external mixed stimuli. It can provide theoretical guidance for the precise control of nonlinear vibrations and the optimal design of the rotating giant magnetostrictive transducers at both microscopic and macroscopic multiple scales. [ABSTRACT FROM AUTHOR]

Magnetostrictive materials have a wide variety of applications due to their great capability as sensors and energy-harvesting devices. However, their brittleness inhibits their applications as magnetostrictive devices. Recently, we developed a continuous magnetostrictive Fe-Co-fiber-embedded epoxy matrix composite to increase the flexibility of the material. In this study, we fabricated random magnetostrictive Fe-Co short fiber/epoxy composite sheets. It was found that the discontinuous Fe-Co fiber composite sheet has the magnetostrictive properties along the orientation parallel to the length of the sheet. Finite element computations were also carried out using a coupled magneto-mechanical model, for the representative volume element (RVE) of unidirectional aligned magnetostrictive short fiber composites. A simple model of two-dimensional, randomly oriented, magnetostrictive short fiber composites was then proposed and the effective piezomagnetic coefficient was determined. It was shown that the present model is very accurate yet relatively simple to predict the piezomagnetic coefficient of magnetostrictive short fiber composites. This magnetostrictive composite sheet is expected to be used as a flexible smart material. [ABSTRACT FROM AUTHOR]

As an intrinsic property, elasticity of soft material is affected significantly by the externally applied alternating magnetic field. Magnetostrictive properties of the grain-oriented (GO) silicon steel under DC-biased and multisinusoidal magnetizations are measured by using a laser-based measuring system. Magnetostriction curves of the GO silicon steel sheet under different magnetizations are obtained and the influence of frequency and DC bias on the magnetostrictive property is observed and analyzed based on the measured data. In addition, the spectrum of magnetostriction under harmonic magnetization is obtained, and the acoustic noise level of the GO silicon steel sheet represented by the A-weighted decibel value caused by magnetostriction is measured under DC-biased and multisinusoidal magnetizations. The measurement results are applied to the simulation of the three-limb laminated core model, and the effects of DC bias and harmonics on magnetic flux density and displacement are analyzed. [ABSTRACT FROM AUTHOR]

We report the magnetic and magnetostrictive behaviors of the pseudobinary ferrimagnetic spinel oxide system (1−x)CoFe2O4–xCoAl2O4 [Co(Fe1−xAlx)2O4], with one end-member being the ferrimagnetic CoFe2O4 and the other end-member being CoAl2O4 that is paramagnetic above 9.8 K. The temperature spectra of magnetization and magnetic susceptibility were employed to detect the magnetic transition temperatures and to determine the phase diagram of this system. Composition dependent and temperature dependent magnetostrictive behaviors reveal an exotic phase boundary that separates two ferrimagnetic states: At room temperature and under small magnetic fields (∼500 Oe), Fe-rich compositions exhibit negative magnetostriction while the Al-rich compositions exhibit positive magnetostriction though the values are small (<10 ppm). Moreover, the compositions around this phase boundary at room temperature (x = 0.35, 0.4, 0.45, 0.5) exhibit near-zero magnetostriction and enhanced magnetic susceptibility, which may be promising in the applications for magnetic cores, current sensors, or magnetic shielding materials. [ABSTRACT FROM AUTHOR]

The mathematical modeling of the magnetoelectric (ME) effect in ME laminates has been established for some simple structures. However, these methods, which are based on the differential equation approach, are difficult to use in other complex structures (e.g., ring structures). In this work, a new established approach based on the generalized Hamilton's principle is used to analyze the ME effect in an ME laminated ring. Analytical expressions for ME voltage coefficients are derived. A comparison with the conventional method indicates that this approach is more convenient when the modeling analysis is performed on complex structures. Further, experimental data are also obtained to compare with the theoretical calculations in order to validate the new approach. [ABSTRACT FROM AUTHOR]

This paper presents a model of the magnetostrictive hysteresis loop with local maximum. The model is based on the differential equations describing magnetostriction due to the domain wall movement as well as domain magnetization rotation. The transition between these mechanisms of magnetization is quantified by the Maxwell–Boltzmann distribution. Moreover, the lift-off phenomenon in the magnetostrictive hysteresis loop is considered. The proposed model was validated on the results of measurements of magnetostrictive hysteresis loops of Mn0.70Zn0.24Fe2.06O4 ferrite for power application and 13CrMo4-5 construction steel. The results of modeling confirm that the proposed model corresponds well with experimental results. Good agreement was confirmed by determination coefficient R2, which exceeded 0.995 and 0.985 for Mn0.70Zn0.24Fe2.06O4 ferrite for power application and 13CrMo4-5 construction steel, respectively. [ABSTRACT FROM AUTHOR]

This paper presents the results of measurements of magnetostrictive properties of Mn0.70Zn0.24Fe2.06O4 ferrite for power applications. Frame-shaped samples were used for measurements to guarantee a uniform magnetizing field and magnetostrictive strain distribution. Magnetostrictive hysteresis loops were measured by semiconductor strain gauges. The results indicate that the magnetostrictive characteristic of Mn0.70Zn0.24Fe2.06O4 ferrite is non-monotonic and magnetostriction changes have opposite signs for higher values of the magnetizing field. [ABSTRACT FROM AUTHOR]

Magnetostrictive transduction has been widely utilized in nondestructive evaluation (NDE) applications, specifically for the generation and reception of guided waves for the long-range inspection of components such as pipes, vessels, and small tubes. Transverse-motion guided wave modes (e.g., torsional vibrations in pipes) are the most common choice for long-range inspection applications, because the wave motion is in the plane of the structure surface, and therefore does not couple well to the surrounding material. Magnetostrictive-based sensors for these wave modes using the Wiedemann effect have been available for several years. An alternative configuration of a sensor for generating and receiving these transverse-motion guided waves swaps the biasing and time-varying magnetic field directions. This alternative design is a reversed Wiedemann effect magnetostrictive transducer. These transducers exhibit a number of unique features compared with the more conventional Wiedemann sensor, including: (1) the use of smaller rare earth permanent magnets to achieve large, uniform, and self-sustained bias field strengths; (2) the use of more efficient electric coil arrangements to induce a stronger time-varying magnetic field for a given coil impedance; (3) beneficial non-linear operating characteristics, given the efficiency improvements in both magnetic fields; and (4) the ability to generate unidirectional guided waves when the field arrangement is combined with a magnetically soft ferromagnetic strip (patch). Reversed Wiedemann effect magnetostrictive transducers will be presented that are suitable for different inspection applications, one using electromagnetic generation and reception directly in a ferromagnetic material, and another design that integrates a magnetostrictive patch to improve its efficiency and enable special operating characteristics. [ABSTRACT FROM AUTHOR]

This study deals with the numerical and experimental study of the effect of weight on the resonant tuning and energy harvesting characteristics of energy harvesting devices using giant magnetostrictive materials. The energy harvesting device is made in a cantilever shape using a thin Terfenol-D layer, stainless steel (SUS) layer and a movable proof mass, among other things. In this study, two types of movable proof mass were prepared, and the device was designed to adjust its own resonant frequency automatically to match external vibration frequency in real time. Three-dimensional finite element analysis (FEA) was performed, and the resonant frequency, tip displacement, and output voltage in the devices were predicted and measured, and the simulation and experiment results were compared. The effects of the weight of the proof mass on self-tuning ability and time-varying behavior were then considered in particular. [ABSTRACT FROM AUTHOR]