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Basic magnetostrictive delay line (MDL) arrangement. (1) MDL; (2) exciting coil; (3) receiving coil.
Source publication
A distributed field sensor is presented in this paper, based on the modulation of microstrains generated by a long exciting coil along the length of a magnetostrictive delay line (MDL). Experimental results are reported concerning as-cast and annealed amorphous FeSiB wires, indicating that spatial resolution is the main advantage of the sensor, whi...
Context in source publication
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... resolution of the order of m and mapping area of the order of centimeters we decided to employ the magnetostrictive delay line (MDL) technique because of its real-time multiplexing characteristics and absence of hysteresis by using certain kinds of magnetostric- tive materials [5,6]. The basic arrangement of such a delay line is illustrated in Fig. 1. The pulsed field transmitted along the length of the delay line, generates pulsed elastic strain due to the magnetostriction effect, which propagates as an elastic wave along the MDL, modifying the magnetization of the corresponding medium. Having polarized magnetically the MDL, such magnetization modification can be detected by means ...
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In this paper we present a method for non destructive testing of ferromagnetic material surfaces. The method is based on the magnetostrictive delay line (MDL) technique. According to this technique a type of balanced MDL structure is used to determine the magnetic permeability of ferromagnetic surface. The distribution of the measured permeability...
A non-contact magnetoelastic torque transducer consisting of a non-magnetic shaft with a portion of its length coated with a magnetostrictive material is studied. A phenomenological theory is developed for predicting the magnetic field of the transducer as a function of coating properties, residual strain, and applied torque. This theory takes into...
Citations
... Christos Manassis developed an optimized distributed field sensor based on MPS response, which can be used in magnetically mapped plane surface, production lines dependent on terrestrial field. [15]. ...
Magnetostrictive waveguide position sensor (MPS) is widely used in industry for position measurement and monitoring. Generally, the generation mechanism of MPS signal is just roughly attributed to the inverse magnetostrictive effect. In this paper, we introduce a novel model of MPS signal generation mechanism which consists of the magnetic domain rotation free (MRF) effect and the magnetic source fluctuation (MSF) effect. Based on this model, the signal intensity is influenced by external magnetic field and the status of magnetostrictive waveguide wire (MPS wire). A series of experiments have been performed to verify the validity of MRF and MSF. The results showed that the signal mechanism model presented here is reasonable. Finally, the practical application of this study is also discussed. As a conclusion, in the application of MPS, the receiving coil must be shielded by ferromagnetic material rather than non-ferrous metal, and the MPS wire cannot be restricted and it must be placed in the center of coil. Otherwise, the signal intensity will be weakened rapidly. The research results indicate that the findings lay a foundation for designing the reasonable structure of MPS, so the new explanation for the signal generation mechanism in this study is of great practical value.
Non-destructive examination of steam generator (SG) tubes of Fast Breeder Reactors is of paramount importance. The inspection needs to be carried out from the inner side of an SG tube due to the constraint in accessibility. Recently, the magnetostrictive ultrasonic guided wave (MUGW) technique has been proposed as an alternative for the inspection of SG tubes. As a commercial MUGW probe for small-diameter ferromagnetic tubes is not available, it needs to be designed and developed with optimum parameters. This paper proposes a three-step optimization approach for the development of a MUGW probe, namely optimization of the diameter and length of a permanent magnet (for bias) finite element modeling based, optimization of the width of the transmitter and receiver coils of the probe by empirical modeling and the optimization of the number of turns of the transmitter and receiver coils by equivalent circuit models. A MUGW probe is fabricated and tested experimentally to validate the optimized parameters. Experiments show the validity of the approach in terms of generation, long-range propagation (47.6 m) of L(0,2) mode at 300 kHz, and the required sensitivity (multiple 10% wall thickness deep uniform wall loss circumferential grooves) in SG tubes.
To enhance the signal intensity of magnetostrictive position sensor (MPS), a new method of bipolar pulse excitation (BPE), and a new structure of single-end damper (SED) are proposed in this paper. Two torsion strain waves, named as W1 and W2 waves, are generated by the BPE, and the W1 wave is reflected (changed into RW1) by the SED. Based on the principle of wave superposition, the interference between RW1 and W2 is realized by adjusting the structure parameters of the sensor. Therefore, the MPS signal is strengthened 1.8 times approximately as well as the measuring range. The notable difference between the new strategy and the conventional one lies in the reflection wave. In conventional MPS, the smaller the reflection wave is, the better the signal will be. However, the reflection wave should be as strong as possible in the new strategy. After the explanation of BPE and SED, a new model is presented. The validity and feasibility of the proposed strategy are verified by experiments. Finally, the characteristics of BPE and SED, such as the measured object, the polar of excitation pulse, and the limit of signal, are discussed in detail. Research results indicate that the proposed BPE method and SED structure are innovative development to conventional MPS, and are of great practical value.
To strengthen the signal intensity and expand the measuring range of the magnetostrictive position sensor (MPS), a new method using the interference of the wave array (IWA) was proposed in this study. Usually, a torsion strain wave was generated within the waveguide wire of MPS due to the Wiedemann effect. On the basis of the conventional MPS structure with single pulse and single cursor, we further developed a new structure that consists of multi-pulses and multi-cursors to generate a wave array with order n. Then, the wave interference occurred by adjusting the time interval of pulses and the space interval of cursors, which led the signal intensity and measuring range of MPS to be increased n times. After the analysis of the IWA work principle, a signal model was presented, and several experiments were performed to verify the feasibility of the new method. The signal of torsion strain wave at 28 m could be observed clearly in the experimental system with the IWA method of 12-order. According to the IWA method, the measuring range could still be increased with the increase in order n. Finally, the mechanism of how the IWA could enhance the signal and resolve the magnetostrictive nonlinear problem was further discussed. Moreover, the relationship between the limit of order n and the elasticity modulus E of the wire material was also discussed
The magneto-optical Kerr effect (MOKE) completed by other surface sensitive methods as integral low-energy and conversion electron Mössbauer spectroscopy, scanning and transmission electron microscopy and by X-ray diffraction have been used with the aim to trace the surface microstructure and magnetic properties of FeSiB amorphous ribbons prepared by planar flow casting. The general composition of studied samples is Fe80Si(x)B(20−x), where x = 4, 6, 8, 10 at.%.
It is shown that MOKE used for magnetization, hysteresis loop, and domain structure determination is highly beneficial in a detection of both surface crystallization and local ordering of atoms into magnetically different clusters of amorphous structure. Moreover, a combination of blue and red laser with different penetration depths yields unique results concerning the surface anisotropy and depth sensitivity. In the case of samples with 4, 6, and 8 at.% Si MOKE detects two magnetically different phases diverging in coercivity values Hc, however, not varying with the sample composition. These phases have been identified by Mössbauer measurements as FeSi and FeB clusters. Their relationship changes with Si concentration. On the other hand, a strong increase in the surface Hc found for the sample with 10 at.% Si has indicated a nanocrystallization. It was confirmed by electron microscopy, Mössbauer and X-ray diffraction results. The size of nanocrystals has varied between 200 nm and 500 nm.
