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This paper presents the investigation of a directional magnetostrictive patch transducer (MPT) composed of a highly textured Galfenol (Fe–Ga alloy) patch in the use of ultrasonic guided Lamb wave (GLW) inspection techniques for isotropic planar structures. Recently, the actuation and sensing performance of an MPT using a disc patch made of polycrys...
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... a stepper motor, the patch with the strain gauge was rotated to align the patch's RD from parallel to perpendicular orienta- tion with respect to the applied dc magnetic field. The mag- netostriction measurement approach is conceptually illustrated in figure 2. To investigate the magnetostriction influence on its strain measurement direction, the magnetos- triction along the TD of each patch was also tested by the same experimental procedure with the RD/RefD strain mea- surement case. ...
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... combining the individual SAIs for all PZT actuator cases (PZT1, PZT2, …, PZT7 transducers), the integrated SAIs were determined as shown in figure 20. From the integrated SAI results, one can observe that the individual SAIs demonstrate very different GLW sensing features corresponding to the three distinct CMPTs. ...
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... the integrated SAI results, we observed that the SAI of the CMPT using the nickel patch clearly presented the A0 mode reflections from four edge boundaries (see the red box arrows in figure 20(a)). This was because the nickel- based MPT exhibited omnidirectional GLW sensing aspects directly connected to the isotropic magnetostrictive properties of the disc patch made of polycrystalline nickel. ...
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... the SAIs based on CMPTs using the Galfenol patches demonstrated specific GLW sensing features that were very different from the nickel-based CMPT case. In the case of the Galfenol-1 patch, the high intensity area relative to the direct A0 mode, shown in the middle of the SAI in figure 20(b), demonstrated two preferred sensing directions of the Galfenol-1 based CMPT, corresponding to the <110> orientations of the Galfenol-1 patch. The GLW signal data from the PZT1 and PZT7 actuator cases showed large amplitudes, while the PZT4 actuator case demonstrated the lowest amplitude due to the <112> orientation character- istic of the Galfenol-1 patch. ...
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... was because the preferred GLW sensing directions of the Galfenol-1 based CMPT were oriented to the RD and TD of the patch, −45° and 45° directions in the plate, respectively. In the similar manner, the SAI shown in figure 20(c) demonstrated the unidirectional sensing feature of the Galfenol-2 based CMPT, based on the <100> preferred orientation of the Galfenol-2 patch. The high intensity area in the SAI, corresponding to the direct A0 modes, showed the Galfenol-2 based CMPT exhibited outstanding directional sensitivity to the incoming GLWs along the RD of the patch. ...
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... PZT1 actuator was only used to generate GLWs, while the orientation of the S1 sensor of the XMPT varied from −135° to 45° with 15° increments with respect to the center of the of the nickel patch. Figure 22 shows the GLW variation on changing the S1 sensor's orientation of the nickel-based XMPT. The received GLW signal data gradually increased as the orientation of the S1 sensor was becoming fully aligned to the PZT1's direction, shown in figure 22(a). ...
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... 22 shows the GLW variation on changing the S1 sensor's orientation of the nickel-based XMPT. The received GLW signal data gradually increased as the orientation of the S1 sensor was becoming fully aligned to the PZT1's direction, shown in figure 22(a). The peak amplitude of the direct A0 mode in the received GLW signal data was determined and the corresponding directional sensitivity was evaluated as shown in figure 22(b). ...
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... received GLW signal data gradually increased as the orientation of the S1 sensor was becoming fully aligned to the PZT1's direction, shown in figure 22(a). The peak amplitude of the direct A0 mode in the received GLW signal data was determined and the corresponding directional sensitivity was evaluated as shown in figure 22(b). The result apparently showed the directional sensing attribute of the nickel-based XMPT's S1 sensor, which provided the relation between the GLW amplitude and the orientation of the S1 sensing coil. ...
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... maximum sensitivity of the S1 sensor was measured when the S1 sensor's orientation was aligned to the actuation PZT transducer. In addition, we observed that the GLW beam spreading pattern, shown in the left corner of figure 22(b), was narrowed down as the excitation frequency for the toneburst input increased. It is necessary to conduct further investigations to clearly understand the GLW beam spreading features regarding the solenoid coil sensor of the XMPT, but we will not discuss in this paper. ...
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... images of the enveloped GLW signal data are shown in figure 23, obtained from two sensing coils (the S1 and S2 sensors) in the XMPTs using the three magnetostrictive patches. The sensing coils of the XMPT were positioned at the original (fixed) locations on the magnetostrictive patch, and the actuation PZT was varied from the PZT1 though PZT7 transducers. ...
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... sensitivity response of the each sensing element of the XMPT was evaluated by measuring the peak amplitude of the direct A0 mode in the received GLW signal data. The corresponding directional sensitivity results for the two sensor cases of the three XMPTs are shown in figure 24. The compensation process described in the previous section was applied to evaluate the final directional sensitivity results. ...
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... compensation process described in the previous section was applied to evaluate the final directional sensitivity results. The top and bottom figures in figure 24 showed the directional sensitivity responses of the S1 and S2 sensors in the XMPTs, respectively. ...
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... the case of the nickel-based XMPT, shown in figure 24(a), we observed that the amplitude of the GLW signal data obtained from the S1 sensor gradually decreased as the actuation PZT altered from the PZT1 through PZT7 transducers, whereas the amplitude of the GLW signal data obtained from the S2 sensor consistently increased. This was because the individual sensing elements of the XMPT Figure 22. ...
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... the case of the nickel-based XMPT, shown in figure 24(a), we observed that the amplitude of the GLW signal data obtained from the S1 sensor gradually decreased as the actuation PZT altered from the PZT1 through PZT7 transducers, whereas the amplitude of the GLW signal data obtained from the S2 sensor consistently increased. This was because the individual sensing elements of the XMPT Figure 22. GLW signal variation as changing the orientation of the rotating S1 sensor of the nickel-based XMPT, for PZT1 actuation: (a) raw GLW signals and the corresponding enveloped signal data and (b) the estimated directional sensitivity based on the direct A0 mode. ...
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... directional sensitivity was exclusively governed by the unique magne- tostrictive characteristics of the Galfenol-1 patch, since the circular magnetic circuit device of the CMPT system had no directional sensing feature. However, the directional sensitiv- ity results shown in figure 24(b) demonstrated that the GLW sensing direction of the Galfenol-1 based XMPT could be controlled by using the proposed XMPT system that contained the cruciform magnetic circuit device. In the case of the S1 sensor of the Galfenol-1 based XMPT, the orientation of the S1 sensing coil was aligned to the direction of the PZT1 actuator parallel to the RD of the patch and the S1 sensor was used to detect the GLWs as the actuation PZT varied from the PZT1 through PZT7 transducers. ...
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... the Galfenol-1 patch case, the S1 sensor of the XMPT using the Galfenol-2 patch exhibited outstanding sensitivity to the GLW generated from the PZT1 actuator parallel to the <100> orientation of the patch. The corresponding results in figure 24(c) demonstrated that the GLW beam spreading pattern of the proposed XMPT could be narrowed down by utilizing the cruciform magnetic circuit device combined with the Galfenol-2 patch. We also observed an additional interesting feature from the S2 sensor case of the Galfenol-2 based XMPT. ...
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... the same manner as the CMPT case, the sparse array imaging technique was employed to obtain additional directional sensitivity information of the individual sensors in the XMPTs, based on the reflected A0 mode waveforms in the received GLW signal data. Figure 25 shows the integrated SAIs (i.e., the combined images of the individual SAIs) evaluated by using the GLW signal data in figure 21. In each magnetostrictive patch case, four integrated SAIs were determined for the individual sensing coils of the XMPT. ...
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... nickel-based XMPT in figure 25(a) apparently demonstrated the directional sensing capability of the XMPT using the cruciform magnetic circuit device. Based on the sensing coils' orientations, the individual sensors of the XMPT showed noticeable directional sensitivity responses, even if the nickel patch retained the isotropic magnetostrictive characteristics and no directional sensing preference. ...
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... on the sensing coils' orientations, the individual sensors of the XMPT showed noticeable directional sensitivity responses, even if the nickel patch retained the isotropic magnetostrictive characteristics and no directional sensing preference. Such directionality aspects of the proposed XMPT could be also observed from the SAI results in the Galfenol-1 based XMPT case, shown in figure 25(b). The Galfenol-1 patch itself had the unique anisotropic magnetostrictive characteristics that resulted in having two preferred GLW sensing orientations, corresponding to the PZT1 and PZT7 actuator directions. ...
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... Galfenol-1 patch itself had the unique anisotropic magnetostrictive characteristics that resulted in having two preferred GLW sensing orientations, corresponding to the PZT1 and PZT7 actuator directions. Since the orientations of the individual sensing coils of the XMPT matched the preferred sensing directions of the Galfenol-1 patch, the SAIs in figure 25(b) showed the equivalent consequences of the directional sensitivity of the Galfenol-1 based XMPT. However, if the orientation of the S1 sensing coil of the Galfenol-1 based XMPT was aligned to the PZT4 actuator (0° direction), the corresponding SAI's maximum intensity would be much smaller than that of the SAIs in figure 25(b). ...
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... the orientations of the individual sensing coils of the XMPT matched the preferred sensing directions of the Galfenol-1 patch, the SAIs in figure 25(b) showed the equivalent consequences of the directional sensitivity of the Galfenol-1 based XMPT. However, if the orientation of the S1 sensing coil of the Galfenol-1 based XMPT was aligned to the PZT4 actuator (0° direction), the corresponding SAI's maximum intensity would be much smaller than that of the SAIs in figure 25(b). The dramatic sensitivity decrease mighty be due to the specific anisotropic magnetostriction properties of the Galfenol-1 patch, which was λ 110 > λ 112 . ...
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... dramatic sensitivity decrease mighty be due to the specific anisotropic magnetostriction properties of the Galfenol-1 patch, which was λ 110 > λ 112 . In the case of the Galfenol-2 patch, we observed from the SAI results in figure 25(c) that the corresponding XMPT showed excellent directional sensitivity for the cases that the orientations of the XMPT's sensing coils were aligned to the <100> preferred orientation of the Galfenol-2 patch. The directional sensitivity responses regarding the S1 and S3 sensors of the Galfenol-2 based XMPT were the combined results between the XMPT's sensing coil configuration and the anisotropic magnetostric- tion effect of the highly textured Galfenol patch. ...
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Citations
... The investigation into guided ultrasonic waves in pipelines has its origins in the early 20th century, marked by Rayleigh and Lamb's initiation of the study on the propagation theory of elastic waves in infinite media. They forged a connection between plate wave numbers and frequencies [67,68]. Within the theoretical exploration of hollow cylindrical structures, Love delved into investigating the propagation characteristics of guided waves within hollow cylindrical pipes [69]. ...
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... It is necessary to distinguish this class of materials from magnetic elastomers, which also consist of ferromagnetic particles and an organic matrix and are also capable of changing linear dimensions when a magnetic field is applied, but due to other mechanisms [82]. In the manufacture of Fe-Ga-based magnetostrictive composites, epoxy resins are most often used as insulators [83][84][85][86][87] because they have suitable mechanical properties for this purpose and are also easy to use. In addition, their important advantage is that their use provides wide opportunities for particle orientation with the help of an external magnetic field during solidification, which makes it possible to increase the magnetostriction of composites. ...
Fe-Ga is a promising magnetostrictive rare-earth free alloy with an attractive combination of useful properties. In this review, we consider this material through the lens of its potential use in magnetostrictive applications at elevated frequencies. The properties of the Fe-Ga alloy are compared with other popular magnetostrictive alloys. The two different approaches to reducing eddy current losses for such applications in the context of the Fe-Ga alloy, in particular, the fabrication of thin sheets and Fe-Ga/epoxy composites, are discussed. For the first time, the results of more than a decade of research aimed at developing each of these approaches are analyzed and summarized. The features of each approach, as well as the advantages and disadvantages, are outlined. In general, it has been shown that the Fe-Ga alloy is the most promising magnetostrictive material for use at elevated frequencies (up to 100 kHz) compared to analogs. However, for a wide practical application of the alloy, it is still necessary to solve several problems, which are described in this review.
... Magnetostriction-based guided wave excitation typically generates higher power compared to excitation based on the Lorentz force principle [102]. Fig. 18 illustrates the excitation principles of three magnetostriction-based EMATs. ...
... The strain in the aforementioned devices is then coupled to the reflection spectrum of a Fiber-Bragg-Grating (FBG) sensor which is shifted due to deformation of the optical fiber encapsulated by the magnetostrictive material. Magnetostriction is a property associated with some materials such as Terfenol, Galfenol and Metglas, wherein strain is introduced in the material on exposure to an external magnetic field due to a high degree of spin-orbit coupling [5]. This behaviour is translated to a wavelength shift in an FBG strain sensor epoxy-glued within the magnetostrictive rod (along the axis of maximal strain). ...
... Ferromagnetic materials with high coercivity are generally used as permanent magnets and in data storage [1], whereas those featuring high electromagnetic loss are relevant for microwave absorption [2]. In contrast, a high magnetic permeability and good ferromagnetic resonance properties are essential for the design of microwave devices such as antennas and tuneable filters [3,4], while magnetostriction is a key property of ferromagnetic materials destined to transduction, micro-displacement actuation, noncontact stress and torque sensing [5][6][7][8][9]. ...
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... Yoo et al. studied the magnetostrictive patch transducer based on Fe-Ga alloy patch. In the case of a static magnetic field and a dynamic magnetic field created by applying alternating current (AC) to a coil, it was found that the direction sensing function of magnetostrictive patch transducer was significantly enhanced by Fe-Ga alloy patch [72]. Fe-Ga alloys have high tensile strength (~500 MPa), good thermal-mechanical properties and exhibit moderate saturated magnetostriction (~350 ppm) under low magnetic fields (~100 Oe), which fill the gap between traditional magnetostrictive materials and rare-earth giant magnetostrictive materials [73][74][75]. ...
... This method has the advantages of stable performance, high sensitivity and low price [150]. A typical setup for strain gauge method is shown in Fig. 6 a [72]. It is a method of transforming magnetostrictive deformation into resistivity change by using strain gauge. ...
Magnetostrictive alloys have attracted increasing attention in biomedical applications because of the ability to generate reversible deformation in the presence of external magnetic fields. This review focuses on the advances in magnetostrictive alloys and their biomedical applications. The theories of magnetostriction are systematically summarized. The different types of magnetostrictive alloys and their preparation methods are also reviewed in detail. The magnetostrictive strains and phase compositions of typical magnetostrictive alloys, including iron based, rare-earth based and ferrite materials, are presented. Besides, a variety of approaches to preparing rods, blocks and films of magnetostriction materials, as well as the corresponding methods and setups for magnetostriction measurement, are summarized and discussed. Moreover, the interactions between magnetostrictive alloys and cells are analyzed and emphasis is placed on the transduction and transformation process of mechanochemical signals induced by magnetostriction. The latest applications of magnetostrictive alloys in remote microactuators, magnetic field sensors, wireless implantable devices and biodegradable implants are also reviewed. Furthermore, future research directions of magnetostrictive alloys are prospected with focus on their potential applications in remote cell actuation and bone repair.
... For the inspection of non-ferromagnetic material or having a high transduction efficiency, nickel patches can be employed for magnetostrictive patch transducers (MPTs) [16]. For the applications of plate, MPTs can be used to excite directional [17][18][19][20][21] as well as omnidirectional SH0 mode [22,23]. Recently, many researchers have briefly reported the work on the interaction of guided waves with defects in regular structures, like, plates and pipes [24][25][26][27][28][29][30][31][32][33]. ...
The quantification of damage, in plates, pipes and such like structures, is one of the current research areas. In this study, to estimate the notch size, shape, and orientation was carried out experimentally based on fundamental shear horizontal mode, SH0 mode. Using least number of transmitters, the reconstruction algorithm for the probabilistic inspection of damage (RAPID) has been used to carry out fast and efficient investigation of scattered waves using SH 0 wave interaction with notch at various incident angles. An approach of ultrasonic guided waves and (RAPID) algorithm, using a direction-tunable shear-horizontal mode array magnetostrictive patch transducer (DT-SHMA-MPT), the notch in a thin aluminum plate is experimented. Firstly, the RAPID algorithm, based on SH 0 mode, is used here to quantitatively study a notch in a thin aluminium plate. Secondly, the imaging application using DT-SHMA-MPT is achieved. Experiments were conducted using an array of eight DT-SHMA-MPTs based on a pitch-catch mode to utilize the scattered waves at the notch. The results obtained through experiments reveal the effect of directionality of the scattered waves and have find out the optimal transducers configuration. The localization, quantification and orientation at the same time are obtained using only two or three transmitters. To improve the accuracy of imaging, a threshold value was selected. The presented approach can be used to detect, locate and image the surface defects in aluminum plate.
... The idea behind choosing the bias point in the position shown is that the largest variation in strain is obtained for the minimum applied dynamic magnetic field, as this is the region of both greatest slope as well as of optimum linearity. Magnetostriction has been used in this way by various authors for ultrasonic generation in a range of materials-see, for example, [33][34][35][36][37][38]. Magnetostrictive Patch Transducers (MPTs) [32] can be used in different shapes and forms for different applications. ...
The characteristics of removable magnetostrictive thin patches are investigated for the
generation of guided waves in plates. The directivity patterns of SH, S0 and A0 modes have been measured in a thin metallic plate for different combinations of static and dynamic magnetic field directions. This used different coil geometries such as racetrack and spiral coils to generate the dynamic magnetic field, as well as separate biasing static magnetic fields from permanent magnets.
This arrangement generated signals via both Lorentz and magnetostrictive forces, and the resultant emitted guided waves were studied for different dynamic and static magnetic field directions and magnitudes. It is demonstrated that different guided wave modes can be produced by controlling these parameters.
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... 7 The highly-textured Galfenol sheet was utilized to develop bio-inspired whisker flow sensors, 8 bending-mode energy harvesters, 9 wireless torque sensors, 10 and ultrasonic Guided Wave (GW) sensors for Structural Health Monitoring (SHM) applications. 11 The Galfenolbased GW sensor showed the excellent directional sensing characteristics along the textured direction of the particular Galfenol patch, equivalent to the <100> preferred orientation. Recently, a set of the Galfenol pieces was utilized in the development of a GW-based Magnetostrictive Phased Array Sensor (MPAS). ...
This paper investigates a study of the use of a Fe-Ga alloy (Galfenol) flake-epoxy composite patch with a circular comb shape for Magnetostrictive Phased Array Sensors (MPAS) used for Structural Health Monitoring (SHM) applications based on the ultrasonic Guided Wave (GW) inspection technique. Galfenol materials have demonstrated a variety of beneficial properties for transducer developments such as high magneto-mechanical coupling, low hysteresis loss, moderate magnetostriction and saturation magnetization, and steel-like manufacturability. However, typical Galfenol materials exhibit anisotropic magnetostrictive characteristics that are disadvantageous for a wide range of applications to the GW SHM, especially phased array technology. To overcome the limitation of the Galfenol materials for the service of the GW phased array approach, we developed the Galfenol composite patch based on the circular comb pattern to improve the directional GW sensing performance using the shape anisotropic effect of the magnetostrictive material. The GW MPAS used in this work consists of a magnetostrictive composite patch directly bonded to a waveguide structure and a non-contact and azimuthally rotatable Hexagonal Magnetic Circuit Device (HMCD) including a biasing magnet and six sensing coils with predetermined directional sensing preferences. Although the GW signals obtained from the MPAS using the Galfenol composite patch were weak, the experimental results validated that the proposed MPAS was capable of detecting GWs using the flake-epoxy composite material and exhibited the obvious directional sensing characteristics. There are only six sensing coils in the HMCD, but the MPAS can acquire additional GW signal data in the Galfenol composite patch by simply altering the rotational orientation of the HMCD, leading to effective array imaging results by suppressing unwanted shadow images induced by the side lobe effect of the directional wavenumber filtering method.
