Change Of Magnetic Flux Research Articles

Crystal structure, magnetic property and cryogenic magnetocaloric effect of Gd4Al2O9 aluminate

Developing magnetic materials with excellent magnetocaloric effect (MCE) is a vital prerequisite for practical magnetic refrigeration (MR) applications. Herein, a single-phased polycrystalline Gd4Al2O9 compound was fabricated using the co-precipitation method, and its structure, magnetic property together with magnetocaloric performance were investigated. The Gd4Al2O9 compound was found to crystallize in the monoclinic structure space group P21/c with lattice parameters a = 7.4852 Å, b = 10.5561 Å, c = 11.1774 Å, β = 108.95° and V=835.3107 Å3, and the constituent elementals had valence states of Gd3+, Al3+ and O2−. Excellent comprehensive MCE performance was observed for the Gd4Al2O9 compound in low-temperature regions. The obtained values of maximal magnetic entropy change, temperature-averaged entropy change (3 K) and relative cooling power under the magnetic flux density change of 0–7 T are 26.31 J/kg·K, 25.09 J/kg·K and 317.05 J/kg. The Gd4Al2O9 compound shows impressive comprehensive MCE performances compared with some recently reported rare earth-based MR materials with prominent performances, meaning that it is a suitable candidate material for low-temperature MR applications.

MoS2-based earth-like self-rotating and magnetically navigated nanorobots for magnetic resonance imaging, cancer cell imaging, and therapy

Microrobots are poised to revolutionize mass transport systems in emerging biomedical applications, yet their erratic motion poses a significant challenge in controlling their movements, particularly in-vivo. In this study, we introduce highly flexible, self-rotating nanorobots based on MoS2 Nanoflowers (NFs), offering superior control over their movement under magnetic field for cancer cell imaging and therapy. These nanorobots, termed MNBOTs, are constructed by embellishing pre-formed MoS2 NFs with NiFe2O3 nanoparticles (NPs) using polymeric linkers, capitalizing on the abundance of disulfide bonds on the MoS2 surface. In-vitro experiments showcased MNBOT's precise control over velocity, trajectory, and curvature, adapting seamlessly to changes in magnetic flux density under electromagnetic navigation. Moreover, MNBOTs were able to release NiFe2O3 NPs successfully in the tumor environment, facilitated by the collapse of disulfide bonds in the presence of glutathione/dithiothreitol, thus ensuring MNBOT's retrieval post-cancer therapy. Furthermore, we leveraged the photo-heat generation and paramagnetic features of MNBOTs for chemo-photothermal therapy (PTT) and magnetic resonance imaging (MRI) in ex vivo clinical settings. The combined effect of chemotherapy-PTT demonstrated remarkable cytotoxicity against MDA-MB-231 cancer cells, highlighting the synergistic potential of MNBOTs. The integration of diverse functionalities within MNBOTs, including remote magnetic navigation, photothermal therapy, and MRI, presents a versatile platform for addressing pressing healthcare needs, thus holding immense potential for future therapeutic and diagnostic applications.

The exploration of multifunctional liquid robotics with ferrofluids: Fabrication, control, operation and sensing

Liquid robotics with arbitrary deformability and rich functionality can adapt to various environmental constraints and perform many significant tasks. To turn this vision into reality, an intelligent liquid system, ferrofluid, which possesses excellent macroscopic and microscopic responsiveness to external magnetic fields, is explored as the rudiment of liquid robotics. Focus is given not only to its improved fabrication and cooperative programming control, but also its underexplored object manipulation and signal transmission. The prepared ferrofluid consists of sterically stabilized ultra-small magnetic nanoparticles suspended in carrier liquids, showing strong stability, flexible mobility, and substantial magnetization. Intelligent locomotion and complex morphology control are successfully achieved by a programmable platform that generates sequential pre-designed magnetic fields through the timing activation of specific electromagnets. Meanwhile, by utilizing the magneto-Archimedes effect, this ferrofluid system can perform multi-dimensional manipulation of objects with densities ranging from 1.1 to 8.9 g/cm3 in cooperation with varying magnetic fields. Furthermore, this system can sense vibrations due to its intrinsic liquid feature and send corresponding signals through detecting the changes in magnetic flux by external coils. Similarly, the flow, concentration, and speed of ferrofluids can also be detected. These advancements in fabrication, control, operation, and sensing are crucial for the development of liquid robotics.

A multi-stable rotational energy harvester for arbitrary bi-directional horizontal excitation at ultra-low frequencies for self-powered sensing

A rotational multi-stable energy harvester has been presented in this paper for harnessing broadband ultra-low frequency vibrations. The novel design adopts a toroidal-shaped housing to contain a rolling sphere magnet which absorbs mechanical energy from bidirectional base excitations and performs continuous rotational movement to transfer the energy using electromagnetic transduction. Eight alternating tethering magnets are placed underneath its rolling path to induce multi-stable nonlinearity in the system, to capture low-frequency broadband vibrations. Electromagnetic transduction mechanism has been employed by mounting eight series connected coils aligned with the stable regions in the rolling path of the sphere magnet, aiming to achieve greater power generation due to optimized rate of change of magnetic flux. A theoretical model has been established to explore the multi-stable dynamics under varying low-frequency excitation up to 5 Hz and 3 g acceleration amplitudes. An experimental prototype has been fabricated and tested under low frequency excitation conditions. The harvester is capable of operating in intra-well, cross-well, and continuous rotation mode depending on the input excitation, and the validated physical device can generate a peak power of 5.78 mW with 1.4 Hz and 0.8 g sinusoidal base excitation when connected to a 405 Ω external load. The physical prototype is also employed as a part of a self-powered sensing node and it can power a temperature sensor to get readings every 13 s on average from human motion, successfully demonstrating its effectiveness in practical wireless sensing applications.

Study of factors affecting the magnetic sensing capability of shape memory alloys for non-destructive evaluation of cracks in concrete: Using response surface methodology (RSM) and artificial neural network (ANN) approaches

Currently, the field of structural health monitoring (SHM) is focused on investigating non-destructive evaluation techniques for the identification of damages in concrete structures. Magnetic sensing has particularly gained attention among the innovative non-destructive evaluation techniques. Recently, the embedded magnetic shape memory alloy (MSMA) wire has been introduced for the evaluation of cracks in concrete components through magnetic sensing techniques while providing reinforcement as well. However, the available research in this regard is very scarce. This study has focused on the analyses of parameters affecting the magnetic sensing capability of embedded MSMA wire for crack detection in concrete beams. The response surface methodology (RSM) and artificial neural network (ANN) models have been used to analyse the magnetic sensing parameters for the first time. The models were trained using the experimental data obtained through literature. The models aimed to predict the alteration in magnetic flux created by a concrete beam that has a 1 mm wide embedded MSMA wire after experiencing a fracture or crack. The results showed that the change in magnetic flux was affected by the position of the wire and the position of the crack with respect to the position of the magnet in the concrete beam. RSM optimisation results showed that maximum change in magnetic flux was obtained when the wire was placed at a depth of 17.5 mm from the top surface of the concrete beam, and a crack was present at an axial distance of 8.50 mm from the permanent magnet. The change in magnetic flux was 9.50 % considering the aforementioned parameters. However, the ANN prediction results showed that the optimal wire and crack position were 10 mm and 1.1 mm, respectively. The results suggested that a larger beam requires a larger diameter of MSMA wire or multiple sensors and magnets for crack detection in concrete beams.

Enhancing Precision in SQUID Sensors: Analyzing Washer Geometry Dependence at the Microscale

In the field of high-precision physical field detection, measurements based on magnetic signals are crucial due to their exceptional accuracy, sensitivity, and stability. Superconducting Quantum Interference Devices (SQUIDs), with their ultra-high sensitivity, have become key in detecting minute changes in magnetic flux. However, with increasing demands for higher precision, further enhancing device performance under quantum constraints remains a significant challenge. This study improved the precision of SQUID sensors by optimizing the geometry of microscale washers using the physical response of superconducting films under micromachining technologies and quantum constraints. Our research extensively examined the effects of square, octagonal, and circular washers on the magnetic field response, shielding currents, and inductance. Experimental results showed that, compared to traditional square washers, octagonal washers significantly enhanced sensor sensitivity and efficiency by minimizing edge magnetic flux and optimizing current distribution. Notably, all observed inductance values exceeded predictions based on traditional empirical formulas, with square washers showing the highest average relative error of 80.8%, while circular and octagonal washers had errors of 65.31% and 66.43%, respectively. This breakthrough not only lays a new theoretical foundation for the design of SQUID sensors but also provides robust evidence for enhancing magnetic field detection through microscale technological innovation.

A novel magnet system—which enables uniformity of radial flux density by means of a parabolic yoke—applied in the Planck-Balance

Abstract A uniform magnetic flux density that is effective in the movement range of the coil is essential for accurate Kibble balance experiments. By utilizing Hopkinson’s law and Kirchhoff’s circuit laws, basic formulas have been derived, providing a method to calculate the magnetic flux density distribution in the airgap of a cylindrical magnet system. A parabolic outer contour of the inner yoke has been found to be a suitable solution to achieve uniformity. Experiments show, that this approach results in a relative change of magnetic flux density in the order of 3 ⋅ 10 − 4 per 8 mm movement range, using a magnet system with a mass of only 2.3 kg. Therefore, the system will be integrated into the upgraded version of PTB’s Planck-Balance—a compact variant of a Kibble balance—aiming for sub 1 ⋅ 10 − 6 accuracy level determination of the geometric factor. The solution described provides a comparatively easy means to design a cylindrical magnet system, using only one permanent magnet disc, without the use of complex simulation software.

High-Coupled Magnetic-Levitation Hybrid Nanogenerator with Frequency Multiplication Effect for Wireless Water Level Alarm.

Hybrid nanogenerators (HNGs) represent a promising avenue for water energy harvesting, yet their commercial viability faces hurdles such as limited power output, poor coupling, and constrained operational lifespans. Here, a highly coupled triboelectric-electromagnetic magnetic-levitation hybrid nanogenerator (ML-HNG) is introduced that shows great potential for water energy harvesting. The ML-HNG fulfills the challenges of high power output, strong coupling, and long operational lifespans. During the contact-separation process of the triboelectric nanogenerator (TENG), the changing magnetic flux in the electromagnetic generator's coils generates a potential difference between the coils and Cu electrodes. The unique design of the ML-HNG employs a shared coil electrode configuration, which enhances the coupling without adding extra volume. This integration allows the ML-HNG to achieve multi-frequency vibrations and multiple output cycles per external longitudinal movement, a phenomenon known as the frequency multiplication effect. With an average power density of 1.69W m-3 in water, the ML-HNG provides continuous power for a thermo-hygrometer and can quickly drive a wireless water level alarm system within a minute. This groundbreaking hybrid nanogenerator design holds significant promise for the efficient and consistent harvesting of low-frequency ocean wave energy, marking a substantial advancement in blue energy technology.

Characterization of magnetic properties, including magnetocaloric effect, of RE5Pt2In4 (RE = Gd-Tm) compounds

The RE5Pt2In4 (RE = Gd-Tm) rare earth compounds have been investigated by means of X-ray diffraction (XRD) as well as by DC and AC magnetometric measurements. The compounds crystallize in an orthorhombic crystal structure of the Lu5Ni2In4-type (Pbam space group, No. 55). With decreasing temperature, the intermetallics undergo a transition from para- to ferro-/ferri- (RE = Gd, Tb, Ho, Er) or antiferromagnetic state (RE = Tm). In case of Dy5Pt2In4, the ferromagnetic state is reached through an intermediate antiferromagnetic order present in a limited temperature range. The critical temperatures of magnetic ordering range from 4.1 K (RE = Tm) up to 108 K (RE = Tb). For the majority of investigated compounds, a cascade of additional magnetic transitions is found below the respective critical temperatures of magnetic ordering. The magnetic moments are found solely on the rare earth atoms, while the moments of the remaining Pt and In atoms are absent or are too small to be detected while accompanied by the strong rare earth’s moments. The magnetocaloric (MCE) performance of RE5T2In4 (RE = Gd-Tm) is found quite good, especially while taking into account the compounds with RE = Ho and Er. Maximum magnetic entropy change (−ΔSMmax) reaches 11.8 (RE = Ho) or 11.4 J ⋅ kg−1 ⋅ K−1 (RE = Er) under magnetic flux density change of 0–9 T. Under the same conditions, the relative cooling power (RCP) and refrigerant capacity (RC) equal 607 and 495 J ⋅ kg−1 (RE = Ho) or 434 and 341 J ⋅ kg−1 (RE = Er).

Numerical Study on Electromagnetic Thermal Performance of Non-Metallic Armoured Optoelectronic Cable Winch System

Non-metallic armoured optoelectronic cable winch systems (NAOCWSs) play critical roles in facilitating signal transmission and powering subsea equipment. Due to the varying depths in these applications, deploying the entire cable length is unnecessary. However, the portion of the cable that remains coiled around the winch can generate an electromagnetic field, which may interfere with signal transmission and induce electromagnetic heating. This can lead to elevated temperatures within the system, affecting the cable’s lifespan. Consequently, this study examines the distributions of magnetic and temperature fields within the NAOCWS with different currents (10–30 A) and numbers of winding layers (1–10). Findings indicate that the magnetic flux density (MFD) changes periodically, and the period is closely related to the distance between the cables. At the centre of the cable, the flux density is minimum. Temperature distribution correlates with both current amplitude and the number of winding layers, where an increase in either parameter amplifies the temperature variance between the edge and intermediate cables within the same layer. The current does not affect the internal temperature distribution pattern. With the number of winding layers determined, the layer where the highest temperature of the system is located is well defined and does not vary with current.

Design of smart magnetic thin-sheet structure based wireless sensors-array arrangement for intraoral-pressure sensing approach

During orthodontic treatments, orthodontists want to simultaneously measure different kinds of intraoral pressure of a patient to determine a suitable orthodontic treatment plan for the patient. To achieve this, an intraoral pressure sensors-array with a specific arrangement in the oral cavity is needed. Hence, in this paper, we design a smart magnetic thin-sheet structure based wireless sensors-array arrangement for intraoral-pressure sensing for orthodontics to determine the above suitable treatment plan. In general, the sensors-array consists of multiple sensing modules. Each module consists of two parts: the first part is a transmitting/receiving electromagnet which is connected to a reference electromagnet in a balanced inductance bridge configuration while the second part is a smart magnetic thin-sheet structure based high-permeable sensing diaphragm. A voltage input is applied to the reference electromagnet and transmitting/receiving electromagnet, while the voltage output is measured from the transmitting/receiving electromagnet, respectively (the transmitting/receiving electromagnet can transmit the magnetic flux as well as receive or sense the change of magnetic flux). When the sensing diaphragm (which is placed in proximity to the transmitting/receiving electromagnet) undergoes a displacement, the gap between the sensing diaphragm and transmitting/receiving electromagnet changes. This subsequently changes surrounding magnetic flux, and consequently results in a change in magnetic reluctance between the sensing diaphragm and transmitting/receiving electromagnet. Thus, the voltage output of the transmitting/receiving electromagnet is changed accordingly. Based on this operation principle, furthermore, we use multiple transmitting/receiving electromagnets to form a compact (specifically arranged) sensors-array. The results show that specifically arranged sensors-array can provide measurement results in multiple points in the oral cavity to the orthodontists, as a simplified decision-making reference for the orthodontists to determine the clinical treatment plan for patients.

Measuring stress of strand using magnetic barkhausen noise measured by solenoid-type sensor

ABSTRACT This paper presents a new approach on non-destructive stress estimation that involves measuring the magnetic Barkhausen noise (MBN) on prestressed strands using a solenoid-type sensor. Using a contact-type sensor on infrastructure is difficult because prestressed strands are wrapped with protective materials and cannot be directly touched. To test the feasibility of the new idea, a solenoid-type MBN sensor is developed that measures the stress of a seven-wire strand. The sensor consists of a magnetic-field inducing coil and a sensing coil, designed to generate a varying magnetic field and measure the change in magnetic flux, respectively. An infinite impulse response filter is recommended to obtain the MBN from the measured signal, and the root mean square (RMS) is introduced to determine the level of the MBN. An indoor test is performed on a seven-wire strand with a diameter of 15.2 mm. The test shows that the MBN’s RMS decreases as the tensile stress increases. The relationship between the MBN’s RMS and the strand’s stress exhibits a clear trend similar to those observed in previous studies using contact-type sensors. The test results indicate that it is possible to estimate the stress of a strand inside a duct using the solenoid-type MBN sensor.

Evaluation of isothermal and isofield designs of a temperature sensor using magnetic phase transition

Digitalisation and related concepts such as cyber-physical systems and Industry 4.0 have gained focus in the past few decades with the increasing need for real-time data acquisition methods for large-scale use. This study investigates the magnetic flux change throughout a magnetic phase transition and the potential of changing the magnetic moment in a temperature sensor. Magnetothermal properties are experimentally measured using gadolinium to examine characteristics that have strong implications for the proposed temperature sensor. The results are used to propose different device designs for changing magnetic flux. The magnetothermal characteristics identified in the previous investigation are also reconsidered under the scope of these device designs. The results show that while certain characteristics need to be carefully considered throughout material development and the actual device designing process, the magnetic flux behaviour shows potential for temperature sensor application.

Effect of laser-assisted surface modification of NdFeB permanent magnets applicable in high-demand working environment

This article focuses on research on innovative coatings for permanent magnets used in electrical machines, basing on Ti and ZrO2 powders. The coatings provide a permanent chemical bond and have been prepared by applying chemical powders with the help of TRUMPF TruLaser Robot 5020 in a continuous manner. Comprehensive tests of the prepared samples, like scanning electron microscopy (SEM), were carried out to analyze surface quality, porosity, homogeneity, and the possible presence of surface defects. Additionally, the FEM field analysis were performed using the ANSYS Maxwell software which allowed to determine magnetic flux distribution for NdFeB magnets. Verification of software calculations was carried out according to the different environment conditions like high temperature, water, seawater or soil. The authors performed studies of the Magnetic flux density changes for selected magnets without and with selected coatings. Obtained results showed that newly developed, industrial scale laser-assisted method for Neodymium magnets modifications constitutes an ecofriendly, promising way to prepare fine elements for modern machines construction.

An Arduino-based magnetic polarity detector and field intensity display

We have designed a simple Arduino-based device, which runs as magnetic polarity detector and field intensity display. It uses an analog Hall sensor together with the Arduino electronic board. The sign of the magnetic flux density allows us to identify the pole of a magnet or electromagnet, while the absolute value allows us to build an intensity display. This device allows us to visualize, among other topics, the basic functional dependences included into the Biot–Savart law, and particularly the changes in magnetic flux density with distance and current for a current-carrying coil or electromagnet.

A soft magnetoelectric finger for robots’ multidirectional tactile perception in non-visual recognition environments

Robotic fingers with multidirectional tactile perception are of great importance for the robotic exploration of complex unknown space, especially in environments in which visualization is not possible. Unfortunately, most existing tactile sensors for robotic fingers cannot detect multidirectional forces, which greatly limits their potential for further development in navigating complex environments. Here, we demonstrate a soft magnetoelectric finger (SMF) that can achieve self-generated-signal and multidirectional tactile sensing. The SMF is composed of two parts: a ‘finger’ covered with a skin-like flexible sheath containing five liquid metal (LM) coils and a ‘phalangeal bone’ containing a magnet. Due to the changes in magnetic flux through the LM coils caused by external forces, diverse induced voltages are generated and collected in real-time, which can be explained by Maxwell’s numerical simulation. By the analysis of the signals generated by the five LM coils, the SMF can detect forces in varied directions and distinguish 6 different common objects with varied Young’s moduli with an accuracy of 97.46%. These capabilities make the SMF suitable for complex unknown space exploration tasks, as proved by the black box exploration. The SMF can enable the development of self-generated-signal and multidirectional tactile perception for future robots.

A flexible droplet-based triboelectric-electromagnetic hybrid generator for raindrop energy harvesting

Dispersed raindrop energy harvesting has recently attracted extensive interest owing to the huge amount of energy contained in the water. However, most raindrop-based electromagnetic generators (EMGs) and triboelectric generators (TEGs) are unable to efficiently convert raindrop energy into electricity due to the rigid, bulky, and complex structures of EMGs with low output voltage, as well as the unstable and low current output of TEGs. Herein, we developed a flexible droplet-based triboelectric-electromagnetic hybrid generator (D-TEHG) including a droplet-based electromagnetic generator (D-EMG) and a droplet-based triboelectric generator (D-TEG) for efficiently harvesting raindrop energy. A flexible magnetically responsive hydrophobic film (MRHF) fabricated by a simple spray coating method was used in a hybrid power output system for raindrop energy conversion, serving as a "spring-like" structure for contacting and separating the electrodes in the D-TEG part, and as an excitation structure for moving the coil in the D-EMG part. When the D-TEHG was excited by a water droplet, the vibration of the elastic film induced the contact and separation of the two electrodes in the D-TEG part and the magnetic flux change through the coil in the D-EMG part, thus generating a dual electrical signal. When a 58.2 µL droplet was dropped from a height of 50 cm and impacted the D-TEHG, the D-TEG generated a peak open-circuit voltage (VOC) of ∼3.01 V and the D-EMG output a peak short-circuit current (ISC) of ∼11.21 mA. The integrated D-TEHG could generate high-performance power for charging capacitors and driving "DUT" LED arrays. By employing advanced flexible materials and structures, the hybrid generator might open up an avenue that makes efficient collection and utilization of large-area raindrop energy a reality.

Detection of blood coagulation in an extracorporeal circuit using magnetic and absorbance properties

In extracorporeal circulation, intra-circuit blood coagulation can lead to serious problems. However, intra-circuit coagulation cannot be monitored in real-time and is only intermittently monitored by measuring the activated clotting time (ACT). As blood clotting progresses in a circuit, the color of the blood turns from bright red to dark red. And, changes in blood coagulation can be detected using devices with optical sensors because the absorbance is likely to change as blood coagulates. However, the absorbance may also increase when oxygen partial pressure is altered by artificial lungs. Thus, there is a need for a device that is not affected by blood oxygenation. Therefore, we used a magnet and a flux meter to assess changes in the magnetic force with blood coagulation. Thus, there is a need for a device that is not affected by blood oxygenation. Therefore, we used a magnet and a flux meter to assess changes in the magnetic force with blood coagulation. Measurements were made at different flux intensities to capture the magnetic flux changes during blood coagulation. Blood (100 ml) was stored in a beaker. Calcium chloride (CaCl2: 0.2 ml) was then added to the beaker to promote coagulation. Blood from the beaker was drawn into a syringe and set in the magnetic flux measurement fixture, and a magnet was fixed on top of the syringe for 24 min. The flux meter readings increased as the blood coagulated. The results suggest that it is possible to capture magnetic flux density changes during the process of blood coagulation. From the above may lead to the development of a device that monitors coagulation in extracorporeal circuits in real time by monitoring two aspects of the coagulation process: absorbance and magnetic flux density.

Phase matching of electromagnetic wave on moving interface

Due to the boundary conditions of electromagnetic fields and phase matching of electro magnetic waves on interface being the basis to drive the Snell’s laws and Fresnel’s laws, they are also crucial for the analysis of electromagnetic wave propagation in a moving medium. There are mainly two methods to derive the boundary conditions of electromagnetic fields on moving interface. One of them is to use the kinematic integral form, yet this method is based on the classical time-space, and the other is based on the relativistic transformation, the boundary conditions are derived from the scaling effect with geometric method, or from the principle of relativity directly. However, the first one has a form the same as the form obtained by using the kinematic integral form, while the second one obtains a different form. At the same time, the phase matching of electromagnetic wave on moving interface is only discussed by Galileo transformation, however this is unreasonable, because of the relativistic effect cannot be ignored here. Therefore, it is necessary to reexamine the boundary conditions of electromagnetic fields and phase matching of electromagnetic wave on moving interface. Herein, firstly, the relativistic transformation formula of the unit normal vector of moving surface is derived from the surface equation and principle of relativity. Secondly, the boundary conditions of electromagnetic fields on moving interface are given based on the relativistic transformation formula and the non-relativistic transformation formula of the unit normal vector and electromagnetic fields, which show that the boundary conditions of electromagnetic fields on moving interface under the relativistic case and the non-relativistic case have the same form. This is not accidental but definite, because the change of flux of electromagnetic fields, like the change of magnetic flux, from the induction of electromagnetic filed is the same as that from the variation of surface element. Thirdly, the phase matching of electromagnetic wave on moving interface is given based on the relativistic transformation formula of the unit normal vector and the phase matching of electromagnetic wave on resting interface. In the problem of light incident on a homogeneous medium moving at a constant velocity in vacuum or air, using the phase matching of electromagnetic wave on moving interface, the same results can be easily obtained through other methods. The discussion in this study belongs to classical electrodynamics with no quantum effects considered, but the results will provide some conveniences for theoretically analyzing electromagnetic communication, remote sensing and telemetering.

Measurement of Magnetic Flux Density Changes in Mode I Interlaminar Fracture in Magnetostrictive Fiber–Embedded Glass Fiber-Reinforced Polymer Composites

As sensor materials for structural health monitoring (SHM, a nondestructive test for the continuous evaluation of the conditions of individual structural components and entire assemblies), magnetostrictive materials, piezoelectric materials, and optical fibers have attracted significant interest. In this study, the mode I interlaminar fracture load and crack self-detection potential of glass fiber-reinforced polymer (GFRP)–embedded magnetostrictive Fe–Co fibers were investigated via double cantilever beam testing. The results indicated that by controlling the amount of Fe–Co fibers introduced into GFRP, the number of Fe–Co fibers could be reduced without compromising the performance of GFRP. Furthermore, the magnetic flux density increased significantly with crack propagation, indicating that the magnetic flux density change could determine crack propagation.