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Graphical abstract Highlights • A novel giant magnetostrictive rotary actuator (GMRA) based on inchworm motion is developed. • A series of driving signals in strict order is designed to realize high precision stepping rotation motion. • Finite element method (FEM) is employed to analyze the mechanical property of GMRA. • Experiments are conducted to test the overall output performance of GMRA, which prove the advantages of GMRA. Abstract A kind of giant magnetostrictive rotary actuator (GMRA) based on inchworm motion is designed in this paper, which can realize high precision rotation motion in large scale and high speed. Applying a series of square wave signals in strict order, the clamping mechanism and driving mechanism of the actuator are alternately operating to realize high precision stepping rotation motion. Finite element method (FEM) is used to analyze the mechanical property of GMRA, suggesting that the designed structure possesses enough mechanical strength. To test the overall performance of the designed actuator, a prototype is fabricated and a series of experiments are conducted. The results indicate that the actuator can function well under driving voltage between 2 V and 4.5 V with driving frequency no higher than 160 Hz. The minimal and maximum stepping angles are 124.2μrad and 308.5μrad respectively. The peak angular velocity and output torque can reach 57.75 mrad/s and 250 N·mm respectively. The experimental consequences prove that the designed actuator can produce highly precise output under different currents and frequencies. [ABSTRACT FROM AUTHOR]

The dynamic model and vibration suppression of a rotating cantilever beam under magnetic excitations are investigated in this article. The nonlinear constitutive relation of magnetostrictive materials is presented. The layout of the control system is demonstrated and explained. The kinetic energy, potential energy of the system, and work done by the electromagnetic force are obtained. The dynamic equations of the system are obtained and discretized by the Hamilton principle and Galerkin approach, respectively. Based on the negative feedback control method, the control scheme is implemented by the magnetostrictive layer. The dynamic model and control method are validated by the references. Various parameter values of the magnetic excitations and rotating beam systems are investigated to reveal their effects on the control behaviors of the bending vibration. Results illustrate that the magnetic excitations bring negative stiffness in the system and increase the responses of beam greatly. The magnetostrictive suppression is effective and can be regarded as the damping effect in the dynamic equations. Increasing the control gain, bias magnetic field and width ratio of the magnetostrictive layer to the controlled layer are beneficial to the vibration control. However, enlarging the angular velocity and pre-stress is harmful to the vibration suppression. [ABSTRACT FROM AUTHOR]

Highlights • A non-hysteresis magnetization model for the GMA was presented using Arctangent function. • Proposed model is suitable to the condition when the maximum magnetization is higher than 20 kA/m. • Proposed model has similar effects to J-A model on computing the amplitude and change rule of the magnetization curve. • The model's accuracy on predicting the output displacement of GMA was verified using experimental data. Abstract Currently, most of the physics-based magnetization models for giant magnetostrictive actuator are complicated in their mathematical models. These complicated models pose considerable challenges for real-time control. Focus on the above issue, we proposed a fitting magnetization model using Arctangent function, as the inverse of the Arctangent function can solve it very quickly. This function was suitable to model the magnetic behavior of giant magnetostrictive actuator serving in an electronic controlled injector or other types of on-off valves. Applicable range of the model was determined through computing the maximum magnetic field. Then the deviations of the proposed fitting model and Jiles-Atherton model under different parameters were studied to verify the computing effects of the model. Then the effectiveness of the fitting model was verified by experimental results. With a high computing precision and a concise form, the proposed model shows great potentials for the real-time control of giant magnetostrictive actuators. [ABSTRACT FROM AUTHOR]

When the longitudinal mode guided waves based on magnetostrictive effect were employed to inspect the bridge cables, we found that there was a large difference in the signal's amplitude of the same specification cable under different tensile force. This difference would affect the test results and the identification of defects. It is necessary to study the effect of tensile force on the signal for the reliability of detection. Firstly, the effective field theory is employed to take the force as an additional bias magnetic field. Then, the effect of the tensile force on generating and receiving longitudinal mode guided waves based on magnetostrictive effect is obtained by the relationship between the bias magnetic field and the magnetostrictive coupling coefficient. Finally, the experiment of the magnetostrictive sensor is carried out on a Φ5 mm steel wire under different force. The experimental results are in good agreement with the theoretical results. The results show that the existence of the tensile force would change the operation point for generating and receiving the longitudinal mode guided waves based on magnetostrictive effect, which associated with the coupling coefficient. In order to obtain the optimal conversion efficiency for the force state wire and cable, the applied bias magnetic field should be set smaller than the bias magnetic field for the force-free state. [ABSTRACT FROM AUTHOR]

The structural, electronic and magnetic properties of FeGa alloys are studied computationally in the composition range up to 31.25 at.% and experimentally about 27 at.%. Ga content. Using ab initio calculations, it is shown that as Ga content increases, the lattice parameters are found to increase for all types of structures, as opposed to the magnetic moment behavior. The phase diagram is plotted as a function of energy. In agreement with experimental results, the following sequences of phase transformations are observed: D03→A2 ( at.%), D0L1A2 ( at.%), and L1D0B2A2 ( at.%). It is found that the L12 cubic structure possesses the largest degree of spin polarization. Experimental studies of Fe-Ga as cast alloys at a constant heating rate and isothermal annealing carried out by means of in situ neutron diffraction and vibrating sample magnetometry demonstrate the sequence of phase transitions of the I and II order. [ABSTRACT FROM AUTHOR]

Highlights • Lower fracture strength of Terfenol-D in the presence of a magnetic field. • Prediction of Terfenol-D fracture loads by means of three different criteria. • Prediction of fracture initiation loci using three different criteria. • Higher accuracy of SED approach compared to the PM and UMTS criterion. Abstract The mechanical properties of Terfenol-D, a giant magnetostrictive material used in applications such as actuators and sensors, have been barely studied, in particular in the presence of notches. Thus, the aim of this work is to fill this gap present in literature. Three point bending tests have been carried out on U-notched specimens with a notch radius of 0.15 mm. The load has been applied at different distances from the midpoint in order to obtain different combinations of mode I and mode II, with the fraction of mode I always being predominant. The results show that higher contributions of the mode II lead to higher fracture loads. In addition, the data experimentally obtained have then been compared with the predictions provided by three different failure criteria, i.e. the strain energy density (SED) approach, the U-maximum tangential stress (UMTS) criterion and the theory of critical distances (TCD) method. Finally, the fracture initiation angles obtained experimentally have been compared with those proposed by the three approaches, and their weaknesses and strengths have been reported. [ABSTRACT FROM AUTHOR]

In the present study, free vibration of magnetostrictive sandwich composite micro plate with magnetostrictive core and composite face sheets are investigated. The modified couple stress theory is taken into account so as to consider the small scale effects. The surrounding elastic medium is simulated as visco-Pasternak foundation to study the effects of both damping and shear effects. Using energy method, Hamilton's principle and first-order shear deformation theory, the governing equations of motion and related boundary conditions are obtained. Finally, the differential quadrature method is employed to analysis the vibration of magnetostrictive sandwich composite micro plate. In this regard, the dimensionless frequency are plotted to study the effects of small scale parameter, surrounding elastic medium, magnetic field, composite fiber angle, aspect ratio, thickness ratio, and boundary conditions. The results indicate that the magnetic field and composite fiber angle play a key role in the dimensionless frequency of magnetostrictive sandwich composite micro plate. The obtained results in this article can be used to design sensors and actuators, aerospace industry, and control of vibration response of systems. [ABSTRACT FROM AUTHOR]

As the performance of modules improved and the Internet became widespread, various electric appliances in daily life became connected to the Internet. Along with this, related to the method of supplying power to the module, attention is being paid to energy harvesting such as vibrational power generator. A magnetostrictive vibration generator comprising a magnetostrictive material (Fe‐Ga alloy) and a vibrating material is a promising device capable of generating small size and high power. However, selection of the optimum vibration material and analysis of the magnetic circuit for the magnetic characteristics of the Fe‐Ga alloy were insufficient, and it was thought that the vibration power generation device could not fully demonstrate the performance. In this paper, magnetic properties of monocrystalline Fe‐Ga alloy and vibrating material are grasped and magnetic analysis using finite element method is carried out. In addition, actually samples were prepared and compared with the results of magnetic analysis. From this result, we examined the effect of combinations of materials on device performance. [ABSTRACT FROM AUTHOR]

Highlights • Single-phase (Tb,Dy,Gd)(Co,Al) 2 alloys synthesized using high-purity metals. • Temperature dependence of lattice parameters measured in a wide temperature range. • The second order magnetostructural phase transitions like Curie temperatures (from cubic to the rhombohedral phase) are found. • The magnetostrictive properties and the MCE of the Tb 0.2 Dy 0.8−x Gd x Co 1.9 Al 0.1 (x = 0.3, 0.4, and 0.5) compounds were studied in detail. • The influence of partial substitution of Co by Al atoms on the magnetocaloric and magnetostrictive properties (Tb,Dy,Gd)Co 2. • Materials with 'table-like' MCE are found. Abstract The influence of partial substitution of Co by Al atoms on the magnetocaloric and magnetostrictive properties of the multicomponent Tb-Dy-Gd-Co compounds with a Laves phase structure was investigated. The samples were obtained by arc melting using of high-purity rare-earth metals. The crystal structure of Tb 0.2 Dy 0.8 - x Gd x Co 2 - y Al y (x = 0.3, 0.4, and 0.5; y = 0 and 0.1) compounds was monitored by powder X-ray diffraction. The magnetostriction and the magnetocaloric effect in external magnetic field up to 12 and 18 kOe, respectively, were studied in wide temperature range. The Curie temperature of Al-content compounds increases by an average of 20 K, while the magnitudes of the magnetocaloric effect and the magnetostriction slightly decrease. [ABSTRACT FROM AUTHOR]

Highlights • Effect on harvester performances of the magnetic bias correlated with preload. • Output power and voltage versus magnetic bias equations provided. • High output power obtained even with magnets having a relatively small coercive field. • Magnetic vs mechanical bias, at the maximum output power, depict a linear behavior. • Results validated with permanent magnets. Abstract The output power generated by a vibrational magnetostrictive energy harvester depends on several parameters, some of them linked to the mechanical source, as vibration amplitude and frequency, others related to design quantities, like mechanical preload, magnetic bias, coil turns and load impedance. Complex models have been developed in literature to reproduce the behavior of these devices. However, for output variables such as power and voltage, one moves in a space of many variables and it is not trivial to reconstruct an overall behavior of the device. The aim of this paper is to provide a wide picture concerning the device behavior investigating experimentally the output power and voltage as a function of the mechanical and especially magnetic bias, varying the amplitude and frequency of the driving vibration. A galfenol rod (Fe 81 Ga 19) sample inserted in a three-legged magnetizer is utilized to vary the magnetic bias and to provide the flux closure to the sample, while a dynamic test machine provides both the mechanical bias and the driving vibration at different frequencies up to 100 Hz. The paper analysis has highlighted that the output power and voltage depend on the magnetic bias according to an exponentially modified Gaussian distribution. Keeping constant the other parameters and varying the mechanical bias, a family of modified Gaussian distributions is obtained. Moreover, fixing the electric load, the amplitude and frequency of the vibration, the couple of values "magnetic bias – mechanical preload" corresponding to the maximum output power of the device depicts a linear behavior. The results here obtained point out that it is possible to simplify the design of magnetostrictive energy harvesters and to obtain high output power even with permanent magnets providing a relatively small coercive field. The results have been confirmed by using two yokes equipped with permanent magnets on the external columns. The maximum output average power obtained with permanent magnets has been 796 mW equal to 6.5 mW/cm3 with a sinusoidal vibration amplitude of 40 MPa at 100 Hz. [ABSTRACT FROM AUTHOR]

T-shaped ambulatory piezoelectric actuator which can be used for various purposes such as lifesaving and environmental monitoring was proposed. The actuator consists of eight piezoelectric benders, t-shaped stator, and four legs, and it is very simple in structure and has the advantages of being easily manufactured and downsizing. It is also driven by four legs and can be moved forward and backward. The piezoelectric bender was composed of a carbon body and a ceramic plate. Vibration motions of the piezoelectric benders in x and z axes were transfer to the legs and the elliptical displacements at the ends of the legs were obtained by combination of the phase difference of 90 degrees. Characteristics of the actuators were simulated by finite element analysis, and the optimized prototype actuator was fabricated and experimented. [ABSTRACT FROM AUTHOR]

This paper deals with practical issues and solutions related to the use of the giant magnetoimpedance (GMI) for electrical current measurement. It presents an overview of a full attempt of design and realization of an almost industrial GMI-based current sensor or clamp. The sensor combines dc and ac measurements with the same flexible sensitive element. This paper addresses several practical problems encountered in a real measurement environment. In this context, main attention was paid to the impact of the influence quantities that largely condition the implementation strategies and solutions of the sensor. For the intended industrial application, these influence quantities first include the operating temperature. Its impact on the intrinsic sensor response was investigated in an almost industrial temperature range. Second, bending stress on the sensitive element is another involved influence parameter in the toroidal and flexible structure of the sensor. The effect of this was also characterized. Finally, the third considered influence parameter is the effect of magnetic disturbances. These include the eccentricity of the conductor of interest and the impact of the surrounding magnetic fields such as the earth’s field or fields produced by other conductors in close proximity to the sensor. Different strategies of implementation and solutions, taking into account the impact of influence parameters, were proposed and compared. A sensor prototype was realized, and its first performances were given. [ABSTRACT FROM AUTHOR]

This paper describes the development of a new magnetometer calibration device using an active magnetic field compensation technique based on the base quantity of time rather than secondary standard field measurements. The proposed arrangement can be used as a laboratory calibration device that monitors and compensates the ambient dc magnetic field in a magnetically quiet environment. Furthermore, it can be developed to serve as a laboratory primary standard since it is based on the measurement of a base quantity, such as time. The proposed technique is based on the fluxgate magnetization principle and the measurement of the time difference between the two successive output pulses. The laboratory arrangement consists of a long solenoid for 1-D applications, which may be extended to 2-D and 3-D using Helmholtz coils, and a microcontroller for fast signal processing operations, which evaluate and compensate the detected ambient magnetic field using a closed-loop control algorithm. The proposed arrangement is used to obtain the calibration curves of a commercial Hall and a custom-made fluxgate sensor. [ABSTRACT FROM AUTHOR]

The optical frequency-domain reflectometry (OFDR) sensing system and signal processing method, which is based on the short-time Fourier transform, enable us to interrogate reflected wavelengths of fiber Bragg gratings (FBGs) and their relative position along the optical fiber with high spatial resolution. An FBG is an optical fiber with an appropriately inscribed periodic refractive index modulation. When a broadband optical signal is launched into the FBG, narrow wavelength bandwidth is reflected. Due to an attached transducer, such as Terfenol-D, the reflected wavelength changes with the applied magnetic field. The proposed magnetic FBG sensor consists of a small rod of magnetostrictive alloy TbDyFe, also known as Terfenol-D, which has large magnetostriction. The FBG is attached to the Terfenol-D rod with UV glue. Consequently, the external magnetic field is applied to the sensor and as a result, the Terfenol-D rod length increases. The reflected wavelength shift is observed and measured by the OFDR sensing system. Therefore, we determine the external magnetic field along the optical fiber from the reflected Bragg wavelength shift. The measurement results show that the proposed magnetic field sensors based on Terfenol-D using OFDR can be successfully used for measurement of the external magnetic field along an optical fiber. [ABSTRACT FROM AUTHOR]

Magnetostrictive actuators show interesting performances related to high-precision actuation with high-energy density, which focused the interest of research in the past years. Nevertheless, the output deformation is related to the current and the applied stress, through a complex multi-input multi-output (MIMO) hysteresis process. As a consequence, a reliable and accurate control task cannot neglect the stress monitoring. Such task, if performed by an ad hoc stress sensor, e.g., a load cell, will face with the sensor’s placement in the device, resulting in an increase in cost, complexity, and bulkiness of the system. This issue can be circumvent if the current and magnetic flux measurements, available in the control chain, are exploited. To this aim, a novel self-sensing approach to deliver real-time estimation of the stress is presented in this paper, involving some recent results of a thermodynamic compatible MIMO model of hysteresis for magnetostrictive materials. [ABSTRACT FROM AUTHOR]

Abstract The choice of an appropriate seismic source for a specific application is crucial for the success of seismic surveys. In this study, the utilization of two novel seismic sources is discussed for geoengineering applications in the bandwidth of 80–3000 Hz. These are a pneumatic impact and a magnetostrictive vibrator source mainly designed for seismic transmission and reflection applications. Seismic test surveys were carried out on Paleozoic sediment deposits to study a near surface fault zone at the southern rim of the Taunus mountain range in Germany and in crystalline rocks to investigate fracture zones along the Piora Adit of the Gotthard Base Tunnel in Switzerland, respectively. Both sources are evaluated with respect to their seismic wave energy, the sum of the squared amplitudes of first P- and S-arrivals and frequency content, signal to random noise ratio, as well as their suitability with regard to the specific site conditions and applications. Common Midpoint-stacked data of the Taunus survey and pre-stack depth migrated data of the Piora survey were analysed to assess the ability of the seismic sources to image geological structures and to give support for geotechnical aspects. For both test sites, the vibrator source proved to be more suitable to generate body waves than the impact source, which generates strong ground roll noise signals due to its non-controlled signal amplitude spectrum. In fact the control system of the vibrator source enabled improved adaption to varying ground conditions due to a controlled adjustment of the signal amplitude spectrum to optimize resolution and penetration for a given exploration depth. Highlights • Two novel seismic sources developed for small-scale geotechnical applications. • Comparison of two data sets recorded on sedimentary and crystalline rocks. • Application of three-component pre-stack depth migration and common midpoint stacks during data processing • Demonstrate the capability of sources for target-oriented imaging. [ABSTRACT FROM AUTHOR]

The three-dimensional (3D) coupled magneto-elastic dynamic model of a giant magnetostrictive actuator (GMA) was built based on Maxwell’s equations, elasticity, and vibration theories. The general analytical expressions for the 3D internal magnetic field distribution of GMA were derived, and the corresponding analytical solutions were obtained. This analytical model is able to predict the internal magnetic field distribution and the output displacement of GMA system with different physical parameters under external excitations. The dynamic behaviors, such as the amplitude vs. frequency responses and the time domain waveforms of the GMA, were also studied. Analytical solutions showed that the internal magnetic field has a prominent end effect along the axial direction of a giant magnetostrictive material (GMM) rod, whereas a minimal skin effect along its radial direction, which are matched very well with the FEM results. The amplitude-frequency relationship exhibited prominent resonance and anti-resonance characteristic, which is a typical hysteresis feature of the GMA system. In order to testify the validity of the model prediction, a GMA testing system was also established. Excellent agreement was found between the experiment measurements and model predictions in the range of our research (frequency is lower than 300 Hz). The analytical results of the present study have potential applications in the fields of active vibration control and other precision machining of the GMA system. [ABSTRACT FROM AUTHOR]

The dual-resonant enhancement of mechanical and optical response in cavity optomechanical magnetometers enables precision sensing of magnetic fields. In previous working prototypes of such magnetometers, a cavity optomechanical system is functionalized by manually epoxy-bonding a grain of magnetostrictive material. While this approach allows proof-of-principle demonstrations, practical applications require more scalable and reproducible fabrication pathways. In this work, we developed a multiple-step method to scalably fabricate optomechanical magnetometers on a silicon chip, with reproducible performance across different devices. The key step is to develop a process to sputter coat a magnetostrictive film onto high quality toroidal microresonators, without degradation of the optical quality factor. A peak sensitivity of 585 pT/ H z is achieved, which is comparable with previously reported results using epoxy-bonding. Furthermore, we demonstrate that thermally annealing the sputtered film can improve the magnetometer sensitivity by a factor of 6.3. [ABSTRACT FROM AUTHOR]

A frequency-tunable current sensor consisting of Terfenol-D/PZT/Terfenol-D magnetoelectric (ME) laminate and Fe73.5Cu1Nb3Si13.5B9 nanocrystalline alloy has been developed. Almost all ME current-sensing devices have higher outputs at resonance conditions, but this advantage is useful only for narrow bandwidth. For the purpose of broadband current sensing, a frequency up-conversion mechanism is introduced by means of nonlinearity of the field-dependence magnetostriction λ(H). Current sensitivity enhancement is realized by modulating the low-frequency dynamic magnetostrictive strain to its resonance conditions. This solution provides the possibility to achieve resonance-enhanced sensitivity at the power-line frequency of 50 Hz, and the capability to immune the noise floor. Experimental results show that the modulated sensitivity is increased from 48.6mV/A to 178.4mV/A at 50Hz, and a small current step change of 3mA can be clearly distinguished by amplitude or phase of the output signals. These results provide possibilities to accurately detect weak currents in the noise ambient at low frequencies. [ABSTRACT FROM AUTHOR]

A method for measuring the magnetostriction of thin films using a vibrating sample magnetometer is described. We describe the design of a custom sample holder to apply an adjustable bending stress to the sample during measurement and observe the resulting change in the M-H loop. [ABSTRACT FROM AUTHOR]

Three quasi-one-dimensional magnetoelectric (ME) magnetic field sensors, each with a different magnetostrictive wire material, were investigated in terms of sensitivity and noise floor. Magnetostrictive Galfenol, iron-cobalt-vanadium, and iron-nickel wires were examined. Sensitivity profiles, hysteresis effects, and noise floor measurements for both optimally biased and zero-biased conditions are presented. The FeNi wire (FN) exhibits high sensitivity (5.36 mV/Oe) at bias fields below 22 Oe and an optimal bias of 10 Oe, whereas FeGa wire (FG) exhibits higher sensitivity (6.89 mW/Oe) at bias fields >22 Oe. The sensor of FeCoV wire (FC) presents relatively low sensitivity (2.12 mV/Oe), due to low magnetostrictive coefficient. Each ME tube-topology sensor demonstrates relatively high sensitivity at zero bias field, which results from a magnetic shape anisotropy and internal strain of the thin magnetostrictive wire. [ABSTRACT FROM AUTHOR]

We have investigated a method for measuring the dimensions of an individual multilayered Fe- Ga/Cu nanowire (NW) as it changes with induced magnetization. In this study, we demonstrate the proposed approach and establish this as a viable method for measuring the magnetostrictive behavior of an individual Fe-Ga/Cu NW using atomic force microscopy (AFM). When an external magnetic field (~300 Oe) was applied perpendicular to the NW axis, the NW length appeared minimized. When a field (~1000 Oe) was applied parallel to the NW axis, the height profile of the NW was found to be higher than in the case with no parallel external field. Since both ends of the NW were welded to the substrate, the magnetic field induced dimensional change of the NW caused deflection of the NW in the upward direction, which was significant enough to be detected by AFM. An average height difference of 15nm was measured with and without an applied field which was then used to calculate the magnetostriction of the multilayered NW. [ABSTRACT FROM AUTHOR]

This paper analyzes a prototype microgyrosensor that employs the magnetostrictive alloy Galfenol for transduction of Coriolis-induced forces into an electrical output for quantifying a given angular velocity. The magnetic induction distribution in the Galfenol sensor patch depends on its bending shape and magnetoelastic properties and is investigated using a finite element model. Fluctuations in magnetic induction caused by a sinusoidal rotation of the sensor produce an amplitude modulated voltage in a surrounding coil which is simulated and measured. [ABSTRACT FROM AUTHOR]

Bulk ferromagnetic shape memory Fe68-Pd30-Rh2 and Fe66-Pd30-Rh4 (at. %) alloys were strain-forged to produce a 35%-40% reduction in thickness. The reduced alloys were thermally annealed at 950-1050 °C for various times to induce recrystallization. The magnetostriction test demonstrated that the grain size reduction of recrystallization had a direct influence on the magnetic properties of the materials. The magnetostrictive strain measurements revealed that the strain-forged metal treated with thermal recrystallization to induce the fine-grained structure had a higher magnetostriction as well as a higher magnetostrictive susceptibility (Δλ‖ s /Δ H). It was also found that at room temperature, the saturation magnetostriction (λs=77x10-6) of the fine-grained Fe- Pd-Rh alloys strain-forged with thermal recrystallization was higher than that of those without grain size reduction (λs=50-56x10-6), where λs is (2/3)[λ‖ s-λ⊥ s]. In addition, with the magnetic field applied perpendicular to the sample's longitude, the fine-grained Fe-Pd-Rh material contracted by as much as λ⊥ s=-36x10-6. This value is about three times higher than that of alloys without grain size reduction. Microstructure investigation indicated that a magnetic applied field normal to the sample's longitude caused high contraction (λ⊥ s) of the fine-grained Fe-Pd-Rh alloys, which could be ascribed mainly to the grain refinement as well as deformation twins or microtwins (transformation and transverse twins). The study demonstrates that the magnetostrictive strains of Fe-Pd-Rh alloys induced in the L10 martensite by the magnetic field can be attributed to the reorientation of the L10 martensite twin structures. [ABSTRACT FROM AUTHOR]

his paper investigates the origin of large magnetostriction in Fe-Ga alloys using small-angle neutron scattering (SANS) and Kerr microscopy. The SANS data for a single-crystal, electron irradiated, and quenched Fe81Ga19 sample under externally applied magnetic and elastic fields revealed the existence of magnetostrictive nanoclusters spaced at ∼15 nm apart that have a different magnetization than the A2 matrix. Combining the SANS results and the magnetization orientation obtained from the magnetic domain images using a Kerr microscope, it appears that the nanoclusters contribute significantly to the macroscopic magnetostriction. [ABSTRACT FROM AUTHOR]

Highlights • A thermodynamically consistent three-dimensional non-iterative constitutive model is built to predict the nonlinear magnetostrictive behaviour under various operating temperatures. • Experimental setup is developed to measure magnetoelectric voltage coefficient as a function of volume fraction of constituents and the operating temperature. • Homogenized magnetoelectric response of the composites is validated with experimental measurements. • It is observed that the coupling response of composite is strongly influenced by configuration of the composites, volume fraction of materials and the operating temperature. Abstract In this work, experiments have been performed to study the magneto-mechanical behaviour of ( Tb 0.3 Dy 0.7 Fe 2 ) under various operating temperatures. Based on the experimental results, a three dimensional nonlinear constitutive model under thermodynamic framework have been developed to capture the thermo-magneto-mechanically coupled behaviour. Then, the model parameters have been identified using least square approximation. Later, using the developed model, a homogenisation procedure has been introduced to simulate magnetoelectric (ME) coupling behaviour for various temperature and volume ratio of composition for different configurations (T-T, L-T, T-L, L-L) in layered ME composites. In a particular configuration (say L-T) is represented by referring first letter (L) as the direction of external magnetic field and the second letter (T) as the direction of polling in the piezoelectric material. Consequently, an experimental setup has been established to capture the ME voltage coefficient at L-T mode under different operating temperatures. Comparison between the experimental data and the simulation results shows good agreement with each other. Comparing the ME coupling behaviour for various configurations, L-L and L-T configurations are observed to have higher coupling factor. [ABSTRACT FROM AUTHOR]

Based on the established equivalent circuit model of a magnetostrictive vibration generator, the low ac voltage and low power produced by the generator under low acceleration are calculated. Comparisons between the calculated and measured results show that the model can provide reasonable data trends of the generator under different loads. To boost the low ac voltage to a high dc voltage required by electronic devices in low power consumption, two energy extraction circuits (EECs) (i.e., a proportion integration-based EEC and an improved EEC) are studied. The corresponding two harvesting systems, which include the generator and the proposed EECs, are designed and simulated in LTspice for system-level evaluation. It is found that the two harvesting systems can effectively boost a few hundred millivolts of ac voltage to the steady dc voltage under low acceleration and varying load conditions. Moreover, the system with the improved EEC can be powered by the harvested energy to maintain self-sustaining operation, and the batteries in the system can be charged for future start-up operations; thus, the system has strong practicability in the dc supply for the electronic devices. [ABSTRACT FROM AUTHOR]

Experimental and calculating analysis of magnetic losses for Terfenol-D is a necessary step for the design of high-power magnetostrictive transducer. In order to further research the magnetic energy losses characteristics, a Terfenol-D rod is sectioned along different directions, and these slices are made into several square annular sheet samples. The influences of material magnetization direction on the losses are compared and analyzed. The values of magnetic energy losses are measured to investigate their variations at different frequencies and magnetic densities of driving magnetic field. Furthermore, the traditional losses formula is improved. The values of the hysteresis losses, eddy-current losses, and anomalous losses are separated out, and the losses coefficients are achieved through polynomial curve fitting. This paper can provide theoretical and experimental guidance for the high-frequency applications of magnetostrictive materials. [ABSTRACT FROM AUTHOR]

Giant magnetostrictive actuator (GMA) becomes more promising in precision positioning, sophisticated manufacturing, and microelectronic system, because of the excellent performance such as high resolution, rapid response, and large mechanical force. However, the intrinsic hysteresis of GMA is the main sticking point preventing its application in the high precision positioning. In this paper, a Prandtl-Ishlinskii (PI) model is established. To obtain the parameters of the model, the internal time-delay recurrent neural network (RNN) with self-tuning ability is proposed. A series of simulations are conducted to testify the availability of proposed method and the results indicates that the PI model identified by the internal time-delay RNN can accurately describe the hysteresis of GMA with the increase of frequency. [ABSTRACT FROM AUTHOR]

Abstract The dynamic process of nucleation, propagation, and braking of a single domain wall (DW) has been systematically determined in a Fe-based magnetostrictive microwire under an applied axial magnetic field. While in previous reports the Sixtus-Tonks experiments have provided partial information on the process (i.e., the average velocity), in the present study we report on the instantaneous processes involved in the propagation of the DW, as well as the transient process during the DW depinning. The experimental measurements were carried out using the spontaneous Matteucci effect induced during DW propagation due to the small helical magnetization component created during the fabrication process. Highlights • The velocity of a single domain wall is time-resolved in microwires. • The domain wall dynamics is instantaneous and locally determined along the wire. • The processes of nucleation, depinning and braking of the wall are identified. • Matteucci effect is employed to measure the domain wall velocity. [ABSTRACT FROM AUTHOR]

Summary: Pipe risers partially covered by a wall are difficult to test because the concrete causes large attenuation and mode conversion. Both reasons make it difficult to analyze the signal. This paper reports the design of an axial magnetized magnetostrictive patch transducer (AM‐MPT) for efficient transduction of longitudinal guided wave, which can be used to detect defects in concrete‐covered pipe risers. First, the paper started with a theoretical background about the influence of length‐to‐width ratio of the magnetized rectangular patch on the demagnetizing factors and the magnetic field intensity of the patch. Second, the simulation and experimental results proved that the length‐to‐width ratio of the magnetized iron cobalt patch has a great influence on its magnetic field intensity and signal amplitude of the AM‐MPT. Comparison experiments proved that the static magnetic field of AM‐MPT provided by an iron cobalt patch led to larger signal amplitudes than those provided by magnets. Third, the attenuation of L(0,2) in concrete‐covered pipe riser were studied using the AM‐MPT experimentally, which were according with disperse simulation results basically. And the experimental results proved that AM‐MPT was more suitable to be applied in concrete‐covered pipe risers testing than original MPT. Finally, the AM‐MPT was applied in a defect identification of concrete‐covered pipe riser sample. The experimental results for the AM‐MPT and the piezoelectric transducer showed that the AM‐MPT can potentially be applied in pipe riser defect identification. [ABSTRACT FROM AUTHOR]

Magnetostriktive Positionssensoren (MPS) werden für absolute und hochgenaue lineare Positionsmessungen eingesetzt. Diese Sensoren basieren auf einer Laufzeitmessung (engl.: Time-of-Flight (TOF)) einer Körperschallwelle innerhalb eines magnetostriktiven Wellenleiters. Nach dem Stand der Technik werden lediglich Positionswerte und deren Ableitungen, wie Geschwindigkeit oder Beschleunigung bestimmt. In diesem Beitrag wird eine Methode zur Temperaturermittlung am Ende des Wellenleiters beschrieben. Diese basiert auf der Auswertung der temperaturabhängigen Signalveränderungen von Reflexionen, welche am Ende des Wellenleiters entstehen, an dem ein Dämpfungsmaterial angebracht ist. Hierzu werden Algorithmen vorgestellt, um die Temperatur am Ende des Wellenleiters, ohne zusätzliche Hardware, aus dem empfangenen Signal zu ermitteln. Die Herleitungen werden durch Simulationen und Messergebnisse belegt. Weiterhin wird eine Möglichkeit zur vereinfachten Kalibrierung des Verfahrens betrachtet. Mit der vorgestellten Methode kann die ermittelte Temperatur als zusätzlicher Parameter verwendet werden, um z. B. eine temperaturabhängige Positionskalibrierung im Sinne eines Self-X Konzeptes eines „Smart Sensors" zu ermöglichen. Magnetostrictive position sensors (MPS) are used for absolute long-range as well as for high-precision linear position measurement. The working principle of these sensors is based on a Time-of-Flight (TOF) measurement of a structure-borne sound wave within a magnetostrictive waveguide. State-of-the-art techniques only determine the position or physically related parameters like velocity or acceleration. In this paper, a method for temperature estimation at the end of the waveguide is proposed. This is based on temperature dependent changes of reflection patterns that arise at the end of the waveguide where a damping material is placed by design. Various algorithms are discussed to establish how the temperature can be determined by analysis of the received signal without any additional hardware. The theoretical concept is proven by simulations and measurements. Furthermore, a method for simple calibration is evaluated. By applying the presented method temperature can be used as an additional parameter, for instance for position calibration and concepts leading to Self-X features of a smart sensor. [ABSTRACT FROM AUTHOR]

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The rare-earth giant magnetostrictive material has received considerable attention in recent years and is known as a new type of high efficient magnetic – mechanical conversion material. Its performance is far superior to that of other materials such as piezoelectric ceramic and so on. Giant magnetostrictive actuator has been widely used in precise driving occasions for its excellent performance. The experimental analysis system for giant magnetostrictive material is designed. Several important parameters have been discussed separately by static and dynamic experiment. Further, the nonlinear magnetic hysteresis characteristic is analyzed by theoretical method. The turning machining analysis model is established and the analytical solution is verified by comparison with the test result. The influence of various parameters is discussed at the same time. Obviously, the research results and methods provide a basis for giant magnetostrictive actuator. [ABSTRACT FROM AUTHOR]

Magnetostrictive biomimetic whiskers have been used as tactile and flow sensors. Compared to other types of whiskers, such whiskers have the advantage of being able to perform static and dynamic measurements. For dynamic measurement, the whisker’s resolution changes with varying vibration frequency; however, the mechanism for this influence has not been studied yet. Thus, the aim of this study is to investigate the resolution–frequency correlation. First, the structure and operation principle of the whisker were analyzed. Then, the Euler–Bernoulli beam theory was employed to establish the sensing model of the magnetostrictive whisker. Finally, the mapping relationship between sensor resolution and frequency was obtained. The eigenfrequency analysis was implemented by FEM to obtain the frequency response of the whisker. A vibration experimental system was built for dynamic testing. The experimental results were in good agreement with the theoretical calculations. Furthermore, it was noted that the resolution was positively correlated with frequency, and the maximum resolution was attained at the natural frequency (two peak values appeared at the first-order and second-order eigenfrequencies). Our research reveals the manner in which a whisker sensor’s resolution is affected by the vibration frequency. The theoretical model can be used to predict the resolution of magnetostrictive whisker sensors. [ABSTRACT FROM AUTHOR]

Active vibration control to suppress structural vibration of the flexible structure is investigated based on a new control strategy considering structure-actuator interaction. The experimental system consists of a clamped-free rectangular plate, a controller based on modal control switching, and a magnetostrictive actuator utilized for suppressing the vibrations induced by external excitation. For the flexible structure, its deformation caused by the external actuator will affect the active control effect. Thus interaction between structure and actuator is considered, and the interaction model based on magnetomechanical coupling is incorporated into the control system. Vibration reduction strategy has been performed resorting to the actuator in optimal position to suppress the specified modes using LQR (linear quadratic regulator) based on modal control switching. The experimental results demonstrate the effectiveness of the proposed methodology. Considering structure-actuator interaction (SAI) is a key procedure in controller design especially for flexible structures. [ABSTRACT FROM AUTHOR]

This paper discusses two different mechanisms of temperature effects on magnetoimpedance (MI), namely, the internal stress relaxation upon heating and critical behavior of magnetic parameters near the Curie temperature T c . When a microwire is heated, the residual stress is partially released changing the effective anisotropy, which inevitably leads to the temperature dependence of hysteresis and MI. A very large change in impedance up to 200% with moderate temperature increase (50–70 °C) occurs in microwires of Co 66.94 Fe 3.83 Ni 1.44 B 11.51 Si 14.59 Mo 1.69 compositions with high T c ≈ 340 ° C where the magnetostriction changes a sign from negative to positive due to stress relaxation. Proper annealing is demonstrated to stabilize such temperature variations in MI. Near the Curie temperature, the impedance undergoes large variations due to a corresponding drop in the magnetization saturation and magnetic anisotropy. The theoretical modelling reveals an increase in the dc initial permeability when approaching T c , which results in different temperature behaviours of MI at low and high frequencies. This was confirmed experimentally for Co 23.67 Fe 7.14 Ni 43.08 B 13.85 Si 12.26 amorphous microwires ( T c  = 62 °C): at a frequency of 10 MHz the impedance increases with temperature until very close proximity of T c , whilst at a frequency of 300 MHz it continuously decreases with increasing temperature. Controlling the value of T c the impedance temperature dependence can be realized in the industrial temperature range of 20–100 °C. This has potential applications for developing embedded miniature temperature sensors. [ABSTRACT FROM AUTHOR]

Membrane mirror, known for its perspicuous feature of light weight, high packaging efficiency, low manufacturing cost and etc., has been widely used in the precision optical instruments, such as the primary mirror applied on a space telescope. However, how to maintain the membrane mirror's surface shape precision at a high level is still a challenging problem. Therefore, a bi-directional giant magnetostrictive-driven compliant tensioning stage is proposed in this research, and the basic performance of the stage is studied through theoretical analysis, numerical simulation and experimental investigations. First, the performance requirements and conceptual design are presented and illustrated in detail. Second, the Pseudo Rigid Body Model method is selected as the basis of further investigating the stage and the dynamic model is established through Lagrange's equation. Meanwhile, numerical simulations are performed to analyze the basic performances. Finally, a prototype is manufactured and based on this device, some experiments are conducted. The results indicate that the developed tensioning stage is able to achieve the desired capability and could effectively maintain the surface shape precision. [ABSTRACT FROM AUTHOR]

Magnetostrictive iron–gallium alloys are able to dissipate mechanical energy via eddy currents and magnetic hysteresis. The mechanically induced eddy current loss is determined by the piezomagnetic coefficient; the hysteresis loss is usually quantified by the phase lag. This study first characterizes these losses for research grade, <100>-oriented, highly textured, polycrystalline $\mathrm{Fe_{81.6}Ga_{18.4}}$ within the structural frequency range (up to 800 Hz). The magnetic biasing is provided by applying a constant current of 500 mA on a pair of electromagnets; the mechanical excitation is a sinusoidal stress wave (3  $\pm$  0.2 MPa) superimposed on a $-$ 20 MPa constant stress. As stress frequency increases, the piezomagnetic coefficient decreases from 32.27 to 10.33 T/GPa and the phase lag $|\Delta \phi |$ increases from 11.38 $^\circ$ to 43.87 $^\circ$. A rate-dependent finite element framework decoupling eddy current loss and hysteresis loss is then developed. The model accurately reproduces the experimental results in both quasi-static and dynamic regimes. Guided by the knowledge of material properties and the finite element model, a coil-less and solid-state damper is designed which can attenuate vibrations before they propagate and induce structure-borne noise and damage. Modeling results show that the loss factor of this damper can be continuously tuned from 0 to a maximum value of 0.107 by adjusting the precompression on the magnetostrictive component. [ABSTRACT FROM AUTHOR]

A magnetostrictive bioinspired whisker sensor based on a galfenol/beryllium-bronze/galfenol composite cantilever beam was developed in this work. According to the new design concept, the proposed whisker can output positive and negative voltages under different bending directions. Besides, the proposed whisker sensor can realize the bidirectional distance and microforce perception. Using the classical beam theory, a theoretical model was used to predict the output performance of the whisker. An experimental system was established to test the whisker’s output performance. In the experiment, the designed whisker, compared with a traditional unimorph whisker, displayed an output voltage range of −240 to 240 mV. The parameters were as follows: the distance was 0–22 mm, with the microforce sensing range of 9.8–2744 mN, the average distance was 10.90 mm/mV, and the force sensitivity was 11.4 mN/mV. At last, obstacle perception was applied. The experiment showed that the proposed whisker sensor can realize the bidirection tactile perception in one-dimensional space. The work expands the function of the magnetostrictive bioinspired whisker, acquiring the multi-information for single-sensor system. [ABSTRACT FROM AUTHOR]

Data mining and soft computing techniques have been widely used in Jiles-Atherton (J-A) hysteresis model parameters identification for ferromagnetic materials or ferromagnetic composites. However, the model cannot be applied to magnetostrictive composites (MSC). That is because not only the nonmagnetic matrix will change the magnetic field distribution in the composites, but also the magnetostriction will be affected by the fabrication procedure. In order to realize the pre-estimation of the magnetostrictive composites magnetic properties, we present a new prediction method. This method is based on modified J-A hysteresis model, utilizing data mining technique to identify model parameters from the raw measured data of magnetostrictive alloy. A methodology including-experimental determination, MJA model, parameters identification by differential evaluation algorithm, is discussed in detail. Then, the experimental data of magnetostrictive composites are compared to the simulations.The theoretical model agrees with the measurement results very well. Our study provides a reference for the performance evaluation of magnetostrictive composites before the preparation process. [ABSTRACT FROM AUTHOR]

This paper aimed with diagnosis of defects in asynchronous machine. The used method is based on the exploitation of the behavioural laws of magnetostrictive and piezoelectric materials, under harmonic regime, used in the construction of the asynchronous machine. Piezoelectric sensors are used both in the stator and in the rotor. The used one in the stator serves to detect the rupture at the stator windings and the one used in the rotor helps us to detect the rupture of the rotor bars. The produced electric potential in the terminals of piezoelectric sensor is due to the deformation generated by magnetic induction under the effect of magnetostriction. A finite element method (FEM) is selected to be the resolution numerical method. This method is used for modelling the asynchronous machine under anomaly conditions and non-load. [ABSTRACT FROM AUTHOR]

This paper focuses on the safety of high-speed trains under strong crosswind conditions. A new active control strategy is proposed based on the adaptive predictive control theory. The new control strategy aims at adjusting the attitudes of a train by controlling the new-type intelligent giant magnetostrictive actuator (GMA). It combined adaptive control with dynamic matrix control; parameters of predictive controller was real-time adjusted by online distinguishing to enhance the robustness of the control algorithm. On this basis, a correction control algorithm is also designed to regulate the parameters of predictive controller based on the step response of a controlled objective. Finally, the simulation results show that the proposed control strategy can adjust the running attitudes of highspeed trains under strong crosswind conditions; they also indicate that the new active control strategy is effective and applicable in improving the safety performance of a train based on a host-target computer technology provided by Matlab/Simulink. [ABSTRACT FROM AUTHOR]

magnetic field sensor of air-gap Fabry–Perot fiber interferometersis proposed based on magnetostrictive effect. The sensor is consisted of single-model fiber (SMF), air-gap, no-core fiber (NCF) and magnetic fluid. Those are sealed in the capillary, SMF and NCF are connect with air chamber and magnetic fluid column. With the presence of an external magnetic field, air chamber cavity length changes because of the magneto-volume variation of magnetic fluids. This situation causes a change in the optical path difference. Detection of the drift of interference spectrum leads to the detection of the change in magnetic field. When the magnetic field is parallel to the direction in which the capillary is placed, the sensitivity is 0.2347 nm/mT; when the magnetic fluid is perpendicular to the direction in which the capillary is placed, the sensitivity is 0.325 nm/ mT. In addition to this new magnetic fluid sensor, a practical detection system is built, which relative error rate is less than 2%. [ABSTRACT FROM AUTHOR]

AC induction motors are the most common motors used in industrial motion. They are widely used in industrial applications for its simplicity, rugged design, low-cost, low maintenance and direct connection to an AC power source. One of the faults occurring in induction motor is the rotor bar breakage that may rapidly spread to a functional failure with catastrophic consequences. Despite the low cost of an induction motor, production losses due to a functional failure in the motor may be greater than the cost of the motor itself. Therefore, the cost advantages that can be achieved with predictive maintenance justify research in monitoring techniques that can indicate the evolution of the conditions before a failure occurs. In this paper, we demonstrate a magnetic sensor based on fiber Bragg grating (FBG) and magnetostrictive composite made of Terfenol-D particulates immersed in epoxy resin matrix applied to induction motor to detect rotor broken bars. To the best of our knowledge, this work demonstrates by the first time an FBG based magnetic sensor applied to monitor an induction motor with the capability to distinguish defective bars, whereas at the same time, conventional technique of current signature at low loading levels failed to indicate the motor severity. The obtained results indicate that the Terfenol-D based sensor can be used for purposes of monitoring broken rotor bars in high voltage induction motors, even when the motor is installed in a dangerous atmosphere, due to the insulation provided by the optical fiber sensor. [ABSTRACT FROM AUTHOR]

According to the classical theory of Weiss, Landau, and Lifshitz, in a ferromagnetic body there is a spontaneous magnetization field m, such that ∥m∥ = τ0 = const in all points of this material Ω. In any stationary configuration, this ferromagnetic body consists of areas (Weiss domains) in which the magnetization is uniform (i.e. m = const) separated by thin transition layers (Bloch walls). Such stationary configuration corresponds to the minimum point of the magnetostrictive free energy E. We are considering an elastic magnetostrictive body in our paper. The elastic magnetostrictive free energy Eδ depends on a small parameter δ such that δ→ 0. As usual, the displacement field is denoted by u. We will show that each sequence of minimizers (ui, mi) contains a subsequence that converges to a couple of fields (u0, m0). By means of a Γ-limit procedure we will show that this couple (u0, m0) is a minimizer of the new functional E0. This new functional E0 describes the magnetic-elastic properties of the body with microstructure. [ABSTRACT FROM AUTHOR]

In order to predict the performance of magnetostrictive smart material and push its applications in engineering, it is necessary to build the constitutive relations for the magnetostrictive material Galfenol. For Galfenol rods under the action of the pre-stress and magnetic field along the axial direction, the one-dimensional nonlinear magneto mechanical coupling constitutive model is proposed based on the elastic Gibbs free energy, where the Taylor expansion of the elastic Gibbs free energy is made to obtain the polynomial forms. And then the constitutive relations are derived by replacing the polynomial forms with the proper transcendental functions based on the microscopic magneto-mechanical coupling mechanism. From the perspective of microscopic mechanism, the nonlinear strain related to magnetic domain rotation results in magnetostrictive strain changing with the pre-stress among the elastic strains induced by the pre-stress. By comparison, the predicted stress strain, magnetostrictive strain, magnetic induction and magnetization curves agreed well with experimental results under the different pre-stresses. The proposed model can describe not only the influences of pre-stress on magnetostrictive strain and magnetization curves, but also nonlinear magneto-mechanical coupling effect of magnetostrictive material systematically, such as the Young's modulus varying with stress and magnetic field. In the proposed constitutive model, the key material constants are not chosen to obtain a good fit with the experimental data, but aremeasured directly by experiments, such as the saturation magnetization, saturation magnetostrictive coefficient, saturation Young's modulus, linear magnetic susceptibility and so on. In addition, the forms of the new constitutive relations are simpler than the existing constitutive models. Therefore, this model could be applied conveniently in the engineering applications. [ABSTRACT FROM AUTHOR]

We investigated the magnetoelectric properties of a new laminate composite material based on y +140°-cut congruent lithium niobate piezoelectric plates with an antiparallel polarized “head-to-head” bidomain structure and metglas used as a magnetostrictive layer. A series of bidomain lithium niobate crystals were prepared by annealing under conditions of Li2O outdiffusion from LiNbO3 with a resultant growth of an inversion domain. The measured quasi-static magnetoelectric coupling coefficient achieved |αE31| = 1.9 V·(cm Oe)−1. At a bending resonance frequency of 6862 Hz, we found a giant |αE31| value up to 1704 V·(cm Oe)−1. Furthermore, the equivalent magnetic noise spectral density of the investigated composite material was only 92 fT/Hz1/2, a record value for such a low operation frequency. The magnetic-field detection limit of the laminated composite was found to be as low as 200 fT in direct measurements without any additional shielding from external noises. [ABSTRACT FROM AUTHOR]

Lead-free multiferroic composites with enhanced magnetoelectric properties and sensitivity have potential for various multifunctional devices. The magnetoelectric behaviour of CoFe 2 O 4 -(Ba 0.85 Ca 0.15 ) (Zr 0.1 Ti 0.9 )O 3 , (CFO-BCZT) and substituted CFO-BCZT laminate composites prepared by epoxy bonding are investigated in this study. Magnetostrictive CoFe 2 O 4 (CFO) substituted with Ti (CTFO) resulted in a very high piezo-magnetic coefficient (q) of ∼290 × 10 −9  Oe −1 . Lead free piezoelectric (Ba 0.85 Ca 0.15 ) (Zr 0.1 Ti 0.9 )O 3 [BCZT] substituted with Ce 4+ (BCZCT) showed improved piezoelectric coefficients of d 33 ∼ 675 pC/N and g 33 ∼13 mV m/N. Two new trilayer multiferroic laminates were developed with a (2-2) composite connectivity by combining the pure and substituted ferroic phases. Magnetostrictive, ferroelectric, piezoelectric and magnetoelectric properties of CFO-BCZT and CTFO-BCZCT laminate composites were measured and compared in here. CTFO-BCZCT composite exhibited a large magnetoelectric response with a high ME coefficient (α ME ) of ∼950 mV/cm.Oe and also showed an improved magnetoelectric sensitivity at lower magnetic fields, making it a potential lead-free material for magnetoelectric sensing applications. [ABSTRACT FROM AUTHOR]

In this paper, a hybrid sensor to measure the torque and axial force using a magnetostrictive hollow rod is presented. The magnetostrictive material is made up of vanadium permendur alloy. Axial and circular magnetic fields are used in order to excite the sensor. An axial coil and a single wire passing through the material are used in order to generate axial and circular magnetic field, respectively. In order to detect axial and circular flux changes, two orthogonal pickup coils are used. Theoretical modeling of the sensor has been done using piezomagnetic equations of magnetostrictive materials. In order to achieve an estimation of applied magnetic fields to the material, the sensor has been simulated numerically. Then, the sensor has been fabricated and tested under influence of axial forces and torques. Tests show that the sensor can detect and measure the axial force and torque simultaneously. Applying torque causes changes in circular magnetic flux density and applying axial force causes changes in both circular and axial fluxes. That is an indicator for load type detection of the sensor. The ranges of the axial force and torque measurement are 10 kN and 20 N m, respectively. The torque measurement accuracy of the sensor is ± 14.81 % FS, measurement sensitivity of the axial pressure load is 0.012 m V N and measurement sensitivity of the torque is 1.18 m V N ∙ m . [ABSTRACT FROM AUTHOR]