Добірка наукової літератури з теми "Magneto-Mechanical measurements"

This study deals with pseudoplastic deformation of Ni50Mn28Ga22 alloy exhibiting mechanically and magnetically induced crystal reorientation. The new approach was introduced, taking into account crystals with single initial variant as well as nucleation of different orientation. Initially, observations from optical microscope and AFM (atomic force microscope) were correlated with the mechanical measurements from stress-strain machine to characterize boundaries between crystal variants. These observations were subsequently used to clarify the results of the mechanical deformation tests. By magnetizing samples in VSM (vibrating-sample magnetometer), analogous magnetic measurements to mechanical tests were conducted. The two types of measurements were then compared with respect to energy. The discrepancy found between the model and measurements is in agreement with previous studies. Some experimental factors and possible errors that may affect measurement have been discussed. Nevertheless, the observed differences remain an unresolved issue suggesting a need for a modification of the model.

The paper presents the numerical and experimental investigations of the axisymmetric magnetostrictive actuator with a Terfenol-D rod. The applied model consists of equations that describe the magnetic and mechanical displacement fields. The equations of both fields are coupled through a nonlinear magneto-mechanical constitutive law. The model is considered as 2D axisymmetric. The finite element method is used to solve the field equations. Special attention is paid to the proper definition of magneto-mechanical relations. These relations are formed from measurements. A unique test stand is designed for the experimental investigation. The selected results of the simulation are compared with the measurement results. The comparison shows that the applied numerical model is sufficiently accurate.

New experiment systems that can offer electromechanical and electromagnetic coupling loads were established. Measurement skills and technologies under coupling loads have been developed. The experimental difficulties and technical problems, such as insulation, discharge, compressive testing of brittle ferroelectrics and so on, were well resolved. The constitutive experiments of piezo/ferroelectrics or ferromagnetic materials were carried out. Moiré Interferometry was applied to the measurement of transformation of the crack tip in ferroelectric ceramics under coupling loads. The deformation concentration near the internal electrode tip caused by non-uniform electric field was investigated by means of Digital Speckle Correlation Method (DSCM). With an aim to accomplish both measurements of constitutive response of the magnetostrictive materials and the fracture experiments of general soft ferromagnetic materials, a magnetomechanical-coupling testing setup was established, which is controlled by an industrial PC. The software was programmed to monitor the testing process and to deal with the acquired data. The characteristic curves of ferromagnetic materials, such as TbxDy1-xFe2 alloys, were measured, including the hysteresis loops, the magnetostriction curve and stress-strain curve.

This research unveils a versatile Halbach array magnetic device with promising biomedical applications, offering innovative solutions for targeted therapy and disease management in evolving biomedical engineering. This paper explores the potential of a novel Halbach array-based device for harnessing magneto-mechanical phenomena in biomedical applications. The study employs computational modeling using COMSOL Multiphysics to define the device’s magnetic properties and validate its operation within the theoretical prediction. The research catalogs the device’s operational modes and assesses crucial parameters related to magneto-mechanical biomedical modalities, including magnetic field strength, gradient, and force. Experimental validation of numerical findings through magnetic field measurements confirms the device’s multifaceted potential, particularly in targeted drug delivery and tissue engineering applications. Finally, the adaptability of the magnetic arrangements for various scenarios is also highlighted. This investigation provides valuable insights into integrating magneto-mechanical principles into biomedical engineering. It paves the way for further research and innovative approaches in theranostics, positioning the presented apparatus as a promising tool with untapped potential for future exploration and discovery in the evolving biomedical field.

Abstract This study reports the development of a magneto-rheological foam, which consists in a porous matrix filled by ferromagnetic particles. The porous matrix of such a composite being easily deformable, large magnetic properties changes are expected. The measurements of the magnetic properties of such a magneto-rheological foam submitted to a compressive strain are reported. Main aspect of the magnetic properties is the low field magnetic permeability as the function of the compression and filling factor. Then, larger field magnetization measurement allowed to investigate the saturation field as a function of the filling factor. Because of the large amount of pores in the material, the magnetic relative permeability, µ r, is quite small (µ r ∼ 1). However, these materials can be easily deformed over a large range of strain providing important relative variation of the magnetic properties under mechanical solicitation. The composite magnetic permeability is increasing under compression for all the considered filling factors. A model is then developed to understand the variation of the permeability with the strain. Hence, from a simple concept consisting of taking advantage of high deformation of foams, the present study demonstrates the interest of such a highly compressible while cheap composite for obtaining a large magneto-rheological effect.

Abstract The topic of the presented paper aims to demonstrate a new principle of hydrodynamic lubrication in mechanical, thermal and electro-magnetic fields. Up till now, when dealing with the hydrodynamic theory lubrication, many authors of scientific papers have assumed the constant oil dynamic viscosity value without variations caused by temperature crosswise the film thickness. Simultaneously, due to the numerous AFM measurements, it appears that oil temperature gradients and oil viscosity changes in the bearing gap height directions cannot be omitted. Therefore, in this paper, the problem of the viscosity changes across the lubricant thin layer was resolved as the main novelty in principles of mechanical thermal lubrication. The method of solving the mentioned problem was manifested by a general model of semi-analytical solutions of isothermal electro-magneto-elastohydro-dynamic and non-Newtonian, lubrication problem formulated for two deformable rotational surfaces in curvilinear, co-ordinates.

Purpose – The purpose of this paper is to find the method for determining the displacement of the active element in a giant magnetostrictive transducer. Design/methodology/approach – The giant magnetostrictive transducer with the active element made of Terfenol-D has been considered. A structure with an axisymmetrical transducer has been proposed. In the proposed model the coupling of magnetic and mechanical field has been taken into account. Maxwell’s equations for electromagnetics and Navier’s equations for mechanical systems are formulated in weak form and coupled using a nonlinear magneto-mechanical constitutive law for Terfenol-D. In order to obtain the distribution of the magnetic and mechanical fields the finite element method was used. The elaborated nonlinear magnetostrictive model has been implemented by using a finite element weak formulation with COMSOL Multiphysics. Findings – The elaborated model for the giant magnetostrictive transducer allows to take into account the magneto-mechanical coupling as well as the material’s nonlinearity. The calculation results of the strain distributions caused by magnetostrictive forces have been presented. The output displacement of a transducer vs supply current for different compressive preload stresses has been calculated and measured. The simulation and measurements results are in close agreement. Research limitations/implications – Taking advantage of the geometrical structure of the prototype of the giant magnetostrictive transducer the computations are performed in an axial-symmetric domain with cylindrical coordinates (r, z, ϑ). The axisymmetric formulation describes the giant magnetostrictive transducers (GMT) without significant loss of accuracy. This approach leads to smaller numerical models and reduced computational time. Practical implications – The elaborated magneto-mechanical model can be used to the design and optimize the structure of GMT. Originality/value – The paper offers the magneto-mechanical model of the giant magnetostrictive transducer. The elaborated model can predict behavior of the magnetostrictive materials it can be used as a tool for the design process of the giant magnetostrictive transducer.

Stress induced magnetic field changes in epoxy-based Terfenol-D composite materials offer a unique way for stress sensing by using a remote magnetic field sensor. In this paper, we report simultaneous measurements of the stress, strain and emitted magnetic field during compressive tests performed at different temperatures in the range of [Formula: see text]C–65[Formula: see text]C. The observed results are explained based on the physical processes that occur at different stresses and temperature ranges. Measurement results reveal a temperature range ([Formula: see text]C–45[Formula: see text]C) suitable for stress sensing applications, at which the reverse magnetostrictive response is almost temperature insensitive. At 65[Formula: see text]C, the epoxy demonstrated a significant softening due to the glass transition, indicating that a high glass transition temperature is an important desired property for the epoxy matrix.

Cette thèse s'inscrit dans le cadre du projet européen ESSIAL (Electrical Steel Structuring, Insulating and Assembling by means of the Laser technologies), qui vise à utiliser la technologie laser pour le traitement de surface afin de réduire les pertes fer, le bruit et les vibrations d'origine magnétique dans les aciers électriques. L'étude consiste tout d'abord à définir des propriétés magnétiques et magnéto-mécaniques à l'échelle mésoscopique. Ces propriétés sont déterminées à partir d'une homogénéisation du comportement dans la structure magnétique qui présente différents types de domaines (domaines principaux longitudinaux, domaines de surface, domaines secondaires transverses ou hors plan, domaines de fermeture transverses ou hors plan ...). Elle prend en compte différentes contributions énergétiques conservatives et dissipatives grâce à une statistique de type Maxwell-Boltzmann. Les propriétés magnétiques concernées sont la perméabilité et une propriété dynamique dissipative représentant les pertes magnétiques dynamiques. Le comportement magnéto-magnétique est décrit par un module magnétique (élastique conservatif) et le délai magnéto-mécanique (dynamique dissipatif). On étudie de même, à partir des équations de Maxwell, l'effet de la diffusion sur le comportement magnétique et magnéto-mécanique et sur les forces de Maxwell présentes dans les entrefers. La modélisation est complétée par un aspect mécanique vibratoire qui prend en compte l'inertie, la raideur et l'amortissement mécanique. L'intégration des différentes propriétés dans les modèles de diffusion et de vibration permet de reconstruire les cycles d'hystérésis magnétiques et magnéto-mécaniques. En parallèle, des mesures synchronisées, magnétiques et mécaniques, adaptées à ces modèles sont réalisées grâce à un banc d'essai dédié. Les entités étant le champ magnétique de surface, l'induction moyenne dans la section d'une tôle et l'accélération à l'extrémité libre de l'échantillon sont traitées et utilisées pour l'identification des propriétés magnéto-mécaniques en utilisant le modèle de diffusion magnétique et le modèle de vibration longitudinale. L'identification est effectuée en se basant sur la discrétisation par éléments finis et sur des méthodes numériques qui minimisent l'erreur entre les mesures et les modèles. Enfin, l'effet de trois procédés laser de surface à impulsions courtes et ultra-courtes (irradiation, gravure ou scribing, ablation) sur le comportement magnéto-mécanique est obtenu en effectuant une étude paramétrique qui consiste à comparer les propriétés identifiées avant et après traitement. Deux exemples d'application sans entrefer (transformateur monophasé) et avec entrefer (inductance monophasée) sont utilisés pour étudier de manière relative l'impact d'un traitement laser sur les contraintes de Maxwell et la magnétostriction.L'étude proposée permet la détermination des paramètres laser qui permettront une réduction optimale des vibrations et du bruit d'origine magnétique tout en réduisant les pertes fer des noyaux ferromagnétiques doux feuilletés au sein des composants magnétiques des équipements et des machines électriques
This thesis is part of the European project ESSIAL (Electrical Steel Structuring, Insulating and Assembling by means of the Laser technologies), which aims at using laser technology for surface treatment to reduce iron losses, noise and vibrations of magnetic origin in electrical steels. The study consists first of all in defining magnetic and magneto-mechanical properties at the mesoscopic scale. These properties are determined from a homogenization of the behaviour in the magnetic structure which presents different types of domains (longitudinal main domains, surface domains, transverse or out-of-plane secondary domains, transverse or out-of-plane closure domains ...). It takes into account different conservative and dissipative energy contributions thanks to a Maxwell-Boltzmann type statistic. The magnetic properties concerned are permeability and a dynamic dissipative property representing the dynamic magnetic losses. The magneto-magnetic behavior is described by a magnetic modulus (conservative elastic) and the magneto-mechanical delay (dissipative damping). The effect of diffusion on the magnetic and magneto-mechanical behavior and on the Maxwell forces present in the air gaps is also studied using Maxwell's equations. The modeling is completed by a vibrational mechanics aspect which takes into account the inertia, the stiffness and mechanical damping. The integration of the different properties in the diffusion and vibration models allows the reconstruction of magnetic and magneto-mechanical hysteresis cycles. In parallel, synchronized magnetic and mechanical measurements adapted to these models are carried out thanks to a dedicated test bench. The entities being the surface magnetic field, the mean induction in the section of a sheet and the acceleration at the free end of the sample are processed and used for the identification of the magneto-mechanical properties using the magnetic diffusion model and the longitudinal vibration model. The identification is performed based on finite element discretization and numerical methods that minimize the error between measurements and models. Finally, the effect of three short and ultra-short pulse surface laser processes (irradiation, scribing, ablation) on the magneto-mechanical behavior is obtained by performing a parametric study which consists in comparing the identified properties before and after treatment. Two examples of applications without air gap (single-phase transformer) and with air gap (single-phase inductance) are used to study in a relative way the impact of a laser treatment on Maxwell stresses and magnetostriction. The proposed study allows the determination of laser parameters that allow an optimal reduction of vibrations and noise of magnetic origin while reducing iron losses of soft ferromagnetic laminated cores within the magnetic components of electrical equipment and machines

Increasing complexity of aerospace structures facilitates a growing need for structural health monitoring (SHM) systems capable of real-time active damage detection. A variety of sensing approaches have been demonstrated using embedded ultrasonic sensors such as piezoelectric wafer active sensors (PWAS) and magneto-elastic active sensors (MEAS). Common methodologies consider wave propagation (pitch-catch or pulse-echo) and standing wave (vibration or impedance) techniques with damage detection capabilities dependent upon structural geometry, material characteristics, distance to damage and damage size/orientation. While recent studies have employed damage detection and classification approaches that are dependent on cumulative statistics, this study explores the contribution of sensor parameters and experimental setup variability on the damage detection scheme. The impact of variability in PWAS and MEAS are considered on sensor use in ultrasonic and magneto-mechanical impedance damage detection. In order to isolate sensor parameters, measurements were conducted with PWAS in free-free boundary conditions. Variability of PWAS parameters was evaluated by measuring the sensors impedance response. An analytical model of PWAS was used to estimate sensor parameters and to determine their variability. Additionally, experiments using MEAS were performed that demonstrate variation of magneto-mechanical impedance during structural dynamic tests. From these experiments the importance of sensor setup is discussed and its contribution into the overall detection scheme is explored.

Abstract Current wearable technologies strive to incorporate more medical functionalities in wearable devices for tracking health conditions and providing information for timely medical treatments. Beyond tracking of a wearer’s physical activities and basic vital signs, the advancement of wearable healthcare devices aspires to continuously monitor health parameters, such as cardiovascular indicators. To properly monitor cardiovascular health, the wearables should accurately measure blood pressure in real-time. However, current devices on the market are not validated for continuous monitoring of blood pressure at a clinical level. To develop wearable healthcare devices such applications, they must be validated by considering various parameters, such as the effects of varying skin properties. Being located between the blood vessel and the wearable device, the skin can affect the sensor readings of the device. The primary goal of this study is to investigate the effect of skin property on the radial pulse measurements. To this end, a range of artificial vein-inserted skin samples with varying properties is fabricated using Magneto-Rheological Elastomers (MRE), materials whose mechanical properties can be altered by external magnetic fields. The samples include layers to simulate the structure of skin and a silicone vein for the pulse to pass through. Note that they are not intended to represent real human skin-vein properties but created to vary a range of stiffness properties to carry out the study. Experiments are performed using a cam system capable of generating realistic human pulse waveforms to pass through the samples. During the indentation testing, the sample is compressed using a dynamic mechanical analyzer (DMA) to record experienced surface pressure, allowing the pulse patterns to be studied. Various samples are used to probe the effects of base resin hardness, iron content, and magnetic field. A pressure sensor incorporated in the cam simulator is used to benchmark the internal pulse pressure of the vein while the DMA indents the sample in order to note the pulse pressures being passed through the sample. Test results show that the properties of the skin influence the resulting pulse behaviors, particularly the ratio of the recorded pulse pressures from the sensor and the DMA.

Abstract Proportional solenoids are electro-magneto-mechanical transducers, which are widely used as drives for proportional valves in fluid systems. Besides the actuator properties, they exhibit also sensor properties due to air gap-dependent electrical behaviour, e.g. for condition monitoring or position controlling tasks. However, the sensor properties of conventional solenoids are poor due to ambiguities caused by hysteresis effects (magnetic hysteresis, eddy currents) and saturation effects. This paper deals with self-sensing design of proportional solenoids for achieving clear sensor properties by considering the proportional actuator properties. Based on simulation analyses of the behaviour of conventional proportional solenoids, design measures are derived for improving especially sensor properties. A self-sensing design is proposed and implemented as demonstrator. Measurements on the demonstrator show the improved sensor behaviour by largely maintaining the actuator characteristics.

Characteristic phenomenological behavior of MR fluids is typically modeled by Bingham’s equation, which has no fundamental connection to the microstructure of MR fluid and the fully coupled mechanical-electrical-magnetic equations. In this paper microstructurally, kinetic theory-based model of MR fluids (consisting of micro-sized ferrous particles suspended in a Newtonian fluid) are developed. For modeling these composite systems, dumbbell models in which two beads joined by an elastic connector are investigated. In these models the distributed forces from the carrier fluid and from the magnetic field on the suspended particle are idealized as being localized on beads. Microscale constitutive equations relating flow, stress, and particle orientation are produced by integrating the coupled equations governing forces, flow, and orientation over a representative volume of particles and carrier fluid. Coefficients in the constitutive equations are specified not by a fit to macroscale experimental flow measurement but rather in terms of primitive measurements of particle microstructure, carrier fluid, viscosity and density, and temperature. These new models for MR fluids are three dimensional and applicable to any flow geometry, while the Bingham plastic model is in general applicable only to shear flow. The models in this paper reduce to forms similar to Bingham’s model in a simple shear flow, but with coefficients which arise from fundamental electromagnetic considerations and microstructural features such as geometrical, magnetic and mechanical characterization of the particles, quantities measured primitively from the carrier fluid, magnetic field and temperature.

In this paper we discuss the development of estimation and control algorithms for the in-vehicle implementation of the Rotary Magneto -Rheological damper. Specifically, we address the estimation of sprung mass heave rate based on suspension position sensor measurements, the design of roll angle control based on lateral load transfer distribution concept, and the integration of these two with the wheel hop detection and control algorithms. The resulting integrated ride and roll controller is evaluated based on both vehicle dynamic response and ride quality objective criteria.

Impedance method has been explored for damage detection and identification. Typically, when the impedance sensor is integrated onto the mechanical structure to be monitored, its electrical impedance is directly related to the mechanical impedance of the host structure. Thus the change of impedance measurement before and after damage occurrence can be used as the damage indicator. Since the impedance information may be measured at relatively high frequency range, the impedance method could be sensitive to small-sized damage. Generally, piezoelectric transducers are employed in the impedance approach, which can serve as actuator and sensor simultaneously. In this research, a magnetic transducer approach is investigated for impedance based damage detection. To provide design guidelines, the analytical model of the resistive magnetic impedance measurement circuit is formulated. During the formulation, the two-way magneto-mechanical coupling between the transducer and the structure is systematically studied by using the Maxwell’s equations. The preliminary sensor enhancement is achieved by selecting the number of turns of wire in the electrical coil. Moreover, in order to reduce the negative effects of the high inherent inductance and large parasitic resistance of the coil with a large number of turns of wire, a new measurement circuitry is proposed, in which a negative resistive element and a capacitor are introduced to be serially connected with the original resistive circuit. Correlated numerical and experimental studies are carried out to validate the magnetic transducer in impedance based damage detection.

Abstract High speed rotating machineries usually operate under severe conditions and enormous loadings and thus, are susceptible to several problems. One such problem that has caught the attention in recent decades is known as High Cycle Fatigue. More than 60 percent of rotating machinery failures has been attributed to this High cycle Fatigue. Along with High Cycle Fatigue, Vibration, an inherent phenomenon in machineries, also share its part in failure of rotating machineries. Rotating machinery components suffer from high amplitude vibrations when they pass through resonance. Stresses are developed as a result of these vibrations and fatigue in mechanical structures, providing a conducive environment for the development of cracks at Surface. When these surface cracks reach critical size, crack nucleation starts, which ultimately leads to catastrophic failures. So, in order to avoid the disastrous consequences, damping is needed. Damping keeps material’s integrity in case of impact forces, stresses due to thermal shocks in turbo machinery and earth quakes in huge structures. Thin layer of magneto elastic coating can be applied on substrate surface that acts as first line of defense. Large number of coating Processes are available around the globe. The optimized combination of coating material, substrate material and coating technique according to specific application is necessary. These coatings have the capability to combat the phenomenon of oxidation, wear and fatigue acting as a barrier between substrate and hostile environments. Further, they enhance the damping characteristics, and thus allows the high-speed rotating machinery to reach its operational speed without any failure at resonance. In this way, they not only enhance the performance of components in aggressive environments, but also improve the life cycle, saving assets of millions of dollars’ worth. This research is an endeavor to experimentally investigate effect of magneto mechanical coating on damping of AISI 321 Stainless steel. AISI 321 was selected as base material because of its wide applications in engine components of gas turbines, heat exchangers and in different chemical industries. Two types of Air plasma sprayed magneto-mechanical powder (NiAl & CoNiCrAlY) were coated on base material and thickness was maintained up to 250μm in both the cases. Experiments were designed and performed on cantilever beam specimens for dynamic response measurement. Dynamic response of the system was measured to investigate the modal parameters of natural frequencies, damping ratio and time of vibration decay. For damping ratio, vibration analyzer mode was adjusted in time domain and beam was excited by using a hammer. Vibration analyzer showed the vibration decay as a function of time. Logarithmic decrement method was used to calculate the damping ratio in both cases. Dynamic response of all the three cases (NiAl coating, CoNiCrAlY and uncoated AISI321) were compared. Results were very reassuring and showed a significant improvement in damping characteristics.

Abstract High speed rotating machineries usually operate under severe conditions and enormous loadings and thus, are susceptible to several problems. One such problem that has caught the attention in recent decades is known as High Cycle Fatigue. More than 60 percent of rotating machinery failures has been attributed to this High cycle Fatigue. Along with High Cycle Fatigue, Vibration, an inherent phenomenon in machineries, also share its part in failure of rotating machineries. Rotating machinery components suffer from high amplitude vibrations when they pass through resonance. Stresses are developed as a result of these vibrations and fatigue in mechanical structures, providing a conducive environment for the development of cracks at Surface. When these surface cracks reach critical size, crack nucleation starts, which ultimately leads to catastrophic failures. So, in order to avoid the disastrous consequences, damping is needed. Damping keeps material’s integrity in case of impact forces, stresses due to thermal shocks in turbo machinery and earth quakes in huge structures. Thin layer of magneto elastic coating can be applied on substrate surface that acts as first line of defense. Large number of coating Processes are available around the globe. The optimized combination of coating material, substrate material and coating technique according to specific application is necessary. These coatings have the capability to combat the phenomenon of oxidation, wear and fatigue acting as a barrier between substrate and hostile environments. Further, they enhance the damping characteristics, and thus allows the highspeed rotating machinery to reach its operational speed without any failure at resonance. In this way, they not only enhance the performance of components in aggressive environments, but also improve the life cycle, saving assets of millions of dollars’ worth. This research is an endeavor to experimentally investigate effect of magneto mechanical coating on damping of AISI 321 Stainless steel. AISI 321 was selected as base material because of its wide applications in engine components of gas turbines, heat exchangers and in different chemical industries. Two types of Air plasma sprayed magneto-mechanical powder (NiAl & CoNiCrAlY) were coated on base material and thickness was maintained up to 250μm in both the cases. Experiments were designed and performed on cantilever beam specimens for dynamic response measurement. Dynamic response of the system was measured to investigate the modal parameters of natural frequencies, damping ratio and time of vibration decay. For damping ratio, vibration analyzer mode was adjusted in time domain and beam was excited by using a hammer. Vibration analyzer showed the vibration decay as a function of time. Logarithmic decrement method was used to calculate the damping ratio in both cases. Dynamic response of all the three cases (NiAl coating, CoNiCrAlY and uncoated AISI321) were compared. Results were very reassuring and showed a significant improvement in damping characteristics.