Hysteretic Effects Research Articles

Improvement of Giant Magneto-Impedance Effect in Fe-Based Nanocrystalline Wires

In order to obtain materials with more ideal GMI effect, (DZ/Z）max, the substitution effects of R (R = Co, Ni and Cr) for Fe in Fe63.5R10Cu1Nb3Si13.5B9 soft magnetic wires have been studied. We found that although the Finemet composition shown excellent GMI effect, the substitution of Co can raise notably the field sensitivity, Q, Ni makes a little improvements of (DZ/Z）max, and Q, and Cr diminishes the undesirable hysteretic effect. In additions, the influence of annealing conditions upon the GMI effect of the best composition Fe63.5Cr10Cu1Nb3Si13.5B9 was also investigated. It indicated that the sample obtained by the ways of Joule heating under the application of suitable tensile stress exhibits 200% and 30%¤Oe for (DZ/Z）max and Q, respectively. This sample can serve as a proper choice for magnetic sensors.

Modified Clipped-LQR Method for Semi-Active Vibration Reduction Systems with Hysteresis

Smart materials are being applied more and more widely in semi-active vibration reduction systems. Actuators built with their use are characterized by nonlinearities and hysteretic effects. Their omission in mathematical descriptions may lead to deterioration of the vibration reduction systems. For that reason, it is important to take into account these negative phenomena associated with the actuators at the controller synthesis stage. One method for determining the control laws in semi-active vibration reduction systems that is frequently discussed in academic literature is “Clipped-LQR”. The present paper proposes modification of that method to allow inclusion in the controller synthesis of the hysteretic properties and other nonlinearities of an actuator. The method developed was verified by determining the controller for the semi-active suspension of a machine operator’s seat. A magnetorheological damper was used as an actuator. The dynamic properties of the foam covering of the operator’s seat were included in model. Simulation tests were performed on the vibration reduction system and function of vibration transmissibility was determined. The semi-active vibration reduction system tested was compared to a passive system. The considerations presented herein relate to the semi-active suspension of a machine operator’s seat, and the method presented may be applied to other controlled systems with many degrees of freedom.

Variational modeling of shape memory alloys – an overview

Abstract Shape memory alloys can be described in a uniform way relying on energetic considerations only. We present micromechanically motivated models for single and polycrystals. The approach studied here is based on energy minimization and includes hysteretic effects via a simple dissipation ansatz. It is capable of reproducing important aspects of the material behavior such as pseudoelasticity and pseudoplasticity. The influence of anisotropies in the crystalline texture as well as in the elastic constants of the austenite and the martensitic variants is also discussed. Furthermore, regularization is applied in order to receive localized but still mesh independent results for phase distributions in a finite element implementation. The entire presentation emphasizes the usage of variational methods leading to the notion of relaxed potentials. Interrelations to various other applications of these concepts will be highlighted.

Unusual resistive switching induced by voltage in La0.7Sr0.3MnO3 thin films

The hysteretic and reversible resistive-switching effect was observed in La0.7Sr0.3MnO3 films at room temperature. The resistive switching was found to be most obvious in films fabricated at 30 Pa oxygen pressure, and more distinct in films fabricated on SrTiO3 substrates than those fabricated on LaAlO3 substrates. Moreover, La0.7Sr0.3MnO3 films fabricated at a certain oxygen pressure with indium electrodes showed double ‘8’ type current-voltage loops. Some of the results are explained by considering the influence of the interface effect, electrodes and oxygen vacancies, but the mechanism of the double ‘8’ type current-voltage loops remains an open question.

Contrasting diurnal variations in soil organic carbon decomposition and root respiration due to a hysteresis effect with soil temperature in a Gossypium s. (cotton) plantation

To understand the characteristics of the diurnal variation in soil respiration and its response to temperature, we used root exclusion plots, and buried CO2 sensors in situ during the late growing season in northwestern China. Soil organic carbon (SOC) decomposition and root respiration dynamics were quantified. In our study, we found that the diurnal variations in root respiration and soil organic carbon (SOC) decomposition showed a contrasting diurnal pattern. SOC decomposition peaked in the afternoon and was in phase with an increase in soil temperature at 10 cm; whereas root respiration decreased from ~08:00–09:00 and was minimal at ~17:00–18:00 despite an increase in soil temperature. Furthermore, an exponential function explained the diurnal variation in total soil respiration and SOC decomposition (r2 > 0.6, n = 504), but not so for root respiration (r2 < 0.3, n = 504). The fitted Q10 value of 4.3 for SOC decomposition was significantly higher than the Q10 value of 3.1 for root respiration. This result suggested that the root respiration rate had a different temperature sensitivity to the microbial respiration rate. In addition, we observed a significant (p < 0.001) clockwise hysteretic effect for SOC decomposition with respect to soil temperature at 10 cm over a 24 h period, with higher rates when soil temperature was increasing and lower rates when soil temperature was decreasing. By contrast, the diurnal hysteresis in root respiration with soil temperature at 10 cm was always counter-clockwise, with lower rates when soil temperature was increasing than when soil temperature was decreasing. This study emphasizes that root respiration and SOC decomposition have different responses to changing soil temperature. Therefore, modeling the impact of global climate change on soil carbon efflux should consider simultaneously, but separately, the impact of the two components.

Hysteretic behavior and magnetic ordering in CeRuSn

We report the thermodynamic and transport properties of the newly synthesized Ce-intermetallic compound CeRuSn. This ternary stannide possesses an unconventional structure with two Ce sites at room temperature which exhibit different valencies. Just below room temperature there are large thermal hysteretic effects in the magnetic susceptibility, in the specific heat, as well as in electronic and heat transport properties suggesting the formation of an incommensurate charge density wave modulation whose $q$ vector changes as a function of temperature. Our measurements indicate that one site displays magnetic Ce${}^{3+}$ behavior while the other is a valence fluctuator. At $2.7$ K antiferromagnetic long-range order occurs within one-half of the Ce sites, e.g., the magnetic entropy of the transition is $\frac{1}{2}R\mathrm{ln}2$. Below ${T}_{N}$ a series of metamagnetic transitions takes place in rather small fields ($~$1--2 T), leaving a magnetically fluctuating background. Such behavior is unique among the many Ce--transition-metal compounds.

Triaxial MRI-Compatible Fiber-optic Force Sensor

Magnetic resonance imaging (MRI) has been gaining popularity over standard imaging modalities like ultrasound and CT because of its ability to provide excellent soft-tissue contrast. However, due to the working principle of MRI, a number of conventional force sensors are not compatible. One popular solution is to develop a fiber-optic force sensor. However, the measurements along the principal axes of a number of these force sensors are highly cross-coupled. One of the objectives of this paper is to minimize this coupling effect. In addition, this paper describes the design of elastic frame structures that are obtained systematically using topology optimization techniques for maximizing sensor resolution and sensor bandwidth. Through the topology optimization approach, we ensure that the frames are linked from the input to output. The elastic frame structures are then fabricated using polymers materials, such as ABS and Delrin(®), as they are ideal materials for use in MRI environment. However, the hysteresis effect seen in the displacement-load graph of plastic materials is known to affect the accuracy. Hence, this paper also proposes modeling and addressing this hysteretic effect using Prandtl-Ishlinskii play operators. Finally, experiments are conducted to evaluate the sensor's performance, as well as its compatibility in MRI under continuous imaging.

Micromagnetic analysis and development of high sensitivity spin-valve magnetic sensors

In this paper we present a micromagnetic analysis and development of low-field magnetic sensors based on the planar Hall effect (PHE) in Permalloy (Ni80Fe20) thin films and spin-valve structures. We used these sensors for field measurements, biomolecules detection in lab-on-a-chip applications and angle positioning devices. Both field and angular PHE measurements were performed. Some distortions and hysteretic effects were observed at low magnetic fields for the angular dependence of the PHE voltage. Micromagnetic simulations were performed to explain the field and the angular dependence of the PHE voltage. We used dc biasing fields to improve the response of the PHE sensor and we compare these results with our micromagnetic simulations.

High Gain Observer for Induction Motor in Presence of Magnetic Hysteresis

AbstractThe problem of state estimation in induction motors is considered in this paper. In most previous works, motor observers have been designed using standard models, neglecting the saturation and hysteretic effects in the machine magnetic circuit. As a matter of fact, these effects cannot be ignored especially when considering (speed, torque) control strategies involving wide range flux variations, necessary to meet optimal operation conditions when facing significant load torque changes. In this paper, a high gain observer is designed for induction motors based on a model that accounts for the nonlinear hysteretic nature of the magnetic circuit. The observer provides estimates of the magnetizing current and magnetic variables using available measurements i.e. stator currents and voltages, rotor speed. The observer is formally shown to enjoy nice convergence properties. The theoretical result is confirmed by simulation.

Real-time compensation control for hysteresis and creep in IPMC actuators

Hysteresis and creep hinder the effective use of IPMC in sensors and actuators. In order to cope with these disadvantageous effects, a fundamental approach is inverse compensation. This paper presents a hybrid model of hysteresis and creep in piezoelectric actuator, which is constructed by Preisach operator and creep operator. Then, the corresponding inverse models for both hysteresis and creep are developed. Based on the obtained inverse model, a method for real-time compensation of the hysteresis and creep of piezoelectric actuator is applied to the control of system nonlinearities. The efficiency of this new model and the method of real-time inverse control are demonstrated by simulation and experiment based on an IPMC actuator. Using this control concept, the tracking errors caused by hysteretic and creep effects are reduced by approximately one order of magnitude, the result verified the validity of the model and effectiveness of the controller.

Positive-Feedback Theory of Hysteretic Recoil Loops in Hard Ferromagnetic Materials

This paper develops a physically-based analytical theory that can be used to model recoil loops, as well as major loops and first- and second-order return curves, in hard ferromagnetic materials that display return-point memory. Atomic-scale quantum-mechanical considerations lead to basic S-shaped magnetization curves that account for hysteretic effects in major and minor loops, as well as their reversibility and irreversibility. These loops exhibit perfect closure only in the presence of the return-point-memory effect. Field (energy) contributions from this hysteretic scenario are summed with contributions due to the classical-physics domain-scale anhysteretic scenario and to the macroscopic demagnetizing field, to obtain a summed scenario that can model isotropic and certain anisotropic materials. Analytical expressions are obtained for all reversal curves up to second order, under the return-point-memory constraint, so that closed recoil loops can be modeled. The theory is validated by comparison with measured data for five different materials.

Experimental and Numerical Investigation of Nonlinear Piezoelectric Effects Including Minor Hystereses

AbstractPiezoelectric ceramics are often used in active structures for shape and vibration control. Since the operation range is not limited to small signals the nonlinear behaviour of the actuator under high electric loads has to be known. There are several approaches in literature to model the hysteretic effects, each having its assets and drawbacks. When a model is able to reproduce the minor loops of the strain ‐ electric field hysteresis, it often lacks the consideration of stress dependence which is fundamental for actuators attached to elastic structures. On the other hand constitutive models which take into account all ferroelectric and ferroelastic effects are not capable of representing the minor hystereses in acceptable calculation times.In this work a phenomenological constitutive model is verified using the experimental data of an active plate structure. Therefore, the ceramic is characterised under mechanically unconstrained conditions and afterwards attached onto a steel plate. The bonding to the substructure leads to a mechanical stress depending on the actuation state of the ceramic. (© 2010 Wiley‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Comparison of Linear, Nonlinear, Hysteretic, and Probabilistic Models for Magnetorheological Fluid Dampers

Magnetorheological (MR) fluid dampers have a semicontrollable damping force output that is dependent on the current input to the damper, as well as the relative velocity. The mechanical construction, fluid properties, and embedded electromagnet result in a dynamic damper response. This study evaluates four modeling approaches with respect to predicting the multi-input single-output behavior of an experimental MR damper when the inputs are band-limited random signals typically encountered in primary suspension applications. The first two models in this study are static in the sense that there is a unique output for any given set of inputs and no dynamics is present in either model. The third model incorporates a dynamic filter with the nonlinear model to exhibit hysteretic effects, which are known to exist in actual MR dampers. The fourth model is probabilistic and illustrates the dynamic nature of an actual MR damper. The results of this study clearly show the importance of nonlinear and dynamic effects in magnetorheological damper response. This study also highlights the importance of characterizing magnetorheological dampers using excitation signals that are representative of an actual implementation.

Study on the Output Characteristics of Piezoelectricity Generator

. For the purpose of improving the output power of piezoelectricity generator (PG), this paper derivates the improving equivalent circuit of piezoelectricity element according to piezoelectricity effect. The dielectric loss and conductive loss are considered. The dielectric loss is caused by the hysteretic effect between leakage current and electric intensity in the medium inside. The conductive loss is caused by the ceramic particles boundary conditions. The relationship between output voltage and current is set up. The relationship between resistance and output power is set up. The relationship between output voltage and out power is set up. Those relationships are simulated and experimented. From the results, it is can be known that there is an optimum load(200 ) for the maximum output power (70 ) in condition of fixed structure, size and fixed excitation frequency and amplitude. With the increasing of voltage, the current is decreasing with parabolic form and the output power increases lowly to a maximum power firstly, and then decreases fast.

Numerical simulations of gravity‐driven fingering in unsaturated porous media using a nonequilibrium model

This is a computational study of gravity‐driven fingering instabilities in unsaturated porous media. The governing equations and corresponding numerical scheme are based on the work of Nieber et al. (2003) in which nonmonotonic saturation profiles are obtained by supplementing the Richards equation with a nonequilibrium capillary pressure‐saturation relationship, as well as including hysteretic effects. The first part of the study takes an extensive look at the sensitivity of the finger solutions to certain key parameters in the model such as capillary shape parameter, initial saturation, and capillary relaxation coefficient. The second part is a comparison to published experimental results that demonstrates the ability of the model to capture realistic fingering behavior.

Goos–Hänchen shift of the reflection from nonlinear nanocomposites with electric field tunability

A structure of nonlinear metal-dielectric nanocomposites is proposed to control the lateral shift of the reflected beam by tuning an applied electric field. Based on spectral representation theory and stationary phase method, the lateral shift is found to exhibit hysteretic effects including single optical bistability, double optical bistability, and optical tristability. As a consequence, it can be manipulated via the applied field. Moreover, the shift is strongly dependent on the volume fraction, the shape of the metallic particles, and the incident angle. Numerical simulations based on Gaussian waves are in good agreement with our theoretical calculations.

Depinning and dynamics of ac driven vortex lattices in random media

We study the different dynamical regimes of a vortex lattice driven by AC forces in the presence of random pinning via numerical simulations. The behaviour of the different observables is charaterized as a function of the applied force amplitude for different frequencies. We discuss the inconveniences of using the mean velocity to identify the depinnig transition and we show that instead, the mean quadratic displacement of the lattice is the relevant magnitude to characterize different AC regimes. We discuss how the results depend on the initial configuration and we identify new hysteretic effects which are absent in the DC driven systems.

Resistive and magnetic behavior and their correlation in polycrystalline manganite La0.55Ca0.45MnO3

An investigation of calcium-doped lanthanum manganite La0.55Ca0.45MnO3 (LCMO-45) was undertaken with the aim to understand its resistive and magnetic properties and their correlation. A high-quality polycrystalline sample was prepared by the standard solid state reaction route. A study of the zero field electrical resistivity as a function of temperature revealed two-phase behavior (i.e. insulating and metallic phases) separated by a resistivity peak at the characteristic insulator–metal (I–M) transition temperature TP. After analyzing the data, it was concluded that in the high temperature (T>Tp) insulating regime, the adiabatic small polaron (ASP) model fits best the observed results when compared with the other two models: the variable range hopping (VRH) and thermal activation (TA) models: this indicates that polaron hopping is mainly responsible for the conduction mechanism in such materials. Isothermal measurements of magnetization M against the applied magnetic field Hdc revealed various different characteristics such as paramagnetic (PM) behavior at room temperature (RT), ferromagnetism (FM) at lower temperature and increasing hysteretic effects of the sample below 260 K. The variation of dc magnetization M(T) with T under a certain applied magnetic field Hdc exhibited a transition from PM (at RT) to FM phase. Enhanced Hdc was observed to have a great influence on the magnitude of magnetization and on the shape of the M–T curve. Besides, the coincidence of metallic and FM transition regimes as well as the dependence of activation energy and resistivity on magnetization provided sterling evidence that there is a strong correlation between resistive and magnetic behavior, and the same mechanism drives both of them.

The impacts of hysteresis on variably saturated hydrologic response and slope failure

This investigation employs 3D, variably saturated subsurface flow simulation to examine hysteretic effects upon the hydrologic response used to drive unsaturated slope stability assessments at the Coos Bay 1 (CB1) experimental catchment in the Oregon Coast Range, USA. Slope stability is evaluated using the relatively simple infinite slope model for unsaturated soils driven by simulated pore-water pressures for an intense storm that triggered a slope failure at CB1 on 18 November 1996. Simulations employing both hysteretic and non-hysteretic soil–water retention curves indicate that using either the drying soil–water retention curve or an intermediate soil–water retention curve that attempts to average the wetting and drying retention curves underestimates the near-surface hydrologic response and subsequently the potential for slope failure. If hysteresis cannot be considered in the hydrologic simulation, the wetting soil–water retention curve, which is seldom measured, should be used for more physically based slope stability assessment. Without considering hysteresis or using the wetting soil–water retention curve, the potential for landsliding in unsaturated materials may be underestimated and a slope failure could occur when simulations predict stability.

Water bells formed on the underside of a horizontal plate. Part 1. Experimental investigation

In this study we report discovery of a new type of water bell. This is formed by impinging a vertical liquid jet on to the underside of a large horizontal flat plate. After impact, the liquid spreads radially along the plate before falling at an abrupt unspecified radius. This falling liquid may then coalesce to form a curtain which encloses a volume of air. When the flow rate of the impinging jet is altered from the value at initial formation, a pronounced hysteretic effect in the water bell shape can be observed. We present detailed observations of these new phenomena, including the size and nature of the flow underneath the plate and the shape of the liquid curtain. These observations are interpreted theoretically in a companion paper (Part 2, Button et al. vol. 649, 2010, pp. 45–68).