Affiliation:
1. Kalashnikov Izhevsk State Technical University
Abstract
Contactless electromagnetic-acoustic transducers have a set of significant advantages over contact transducers, but at the same time they have significant disadvantages that require the development of effective magnetizing devices. Compared to magnetizing devices that are using permanent magnets, electric current magnetization devices are easily removed from the object of testing and cleaned from contamination by metal particles. Unfortunately, such transducers have significant dimensions and weight.A transducer containing a magnetic circuit magnetized by an electric current coil and two independent electromagnetic inductors located in the gap between the central part of the magnetic circuit and the object of testing has been developed. Inductors are two flat coils, each of them has form like a butterfly. The inductor conductors located in the working area have mutually perpendicular directions; they allow exciting and receiving the transversely polarized acoustic waves without rearranging the transducer. In order to reduce the overall dimensions and mass of the transducer, the mass and dimensional parameters of the magnetizing device were optimized for operating conditions when the magnetization of the object of testing and measurement are performed during the active measurement phase. During the passive measurement phase, which is three times longer than the active phase in time, the magnetizing device cools down. The cyclic mode with alternating active and passive phases made it possible to reduce the weight of the transducer by more than 3 times. In the working area of the transducer with a size of 15×15 mm, with a gap of 1 mm between the magnetic field concentrator and the object of testing, a field with a normal component of 2.4 T is created. The transducer has protection of the magnetization device from overheating, and the cyclic mode of operation allows for continuous performance of up to 30 measurements per minute at an ambient temperature of 20 °C.The developed magnetizing device can be used in solving a number of problems of structuroscopy, thickness measurement, flaw detection by electromagnetic-acoustic methods based on accurate measurement of the propagation time of elastic waves in the object of testing.
Publisher
Belarusian National Technical University
Subject
General Earth and Planetary Sciences,Water Science and Technology,Geography, Planning and Development
Reference35 articles.
1. Hirao M., Ogi H. Electromagnetic Acoustic Transducers: Noncontacting Ultrasonic Measurements Using EMATs. Tokyo: Springer Japan, 2017, 380 p. DOI: 10.1007/978-4-431-56036-4
2. Lü J., Liu G. Magneto-Acousto-Electrical NDT and Improved EMD De-Noising Algorithm. Transactions of Chinese Electrotechnical Society, 2018, vol. 33, no. 17, pp. 3935– 3942. DOI: 10.19595/j.cnki.1000-6753.tces.171126
3. Pei C., Zhao S., Liu T., Chen Z. A new method for plastic strain measurement with Rayleigh wave polarization. Ultrasonics, 2018, vol. 88, pp. 168–173. DOI: 10.1016/j.ultras.2018.04.004
4. Xie S., Tian M., Xiao P., Pei C., Chen Z., Takagi T. A hybrid nondestructive testing method of pulsed eddy current testing and electromagnetic acoustic transducer techniques for simultaneous surface and volumetric defects inspection. NDT & E International, 2017, vol. 86, pp. 153–163. DOI: 10.1016/j.ndteint.2016.12.006
5. Bashirov M.G., Khusnutdinova I.G., Khusnutdinova L.G., Usmanov D.R. Electromagnetic-acoustic method of technical state assessment of power equipment. Industrial Energy, 2016, no. 12, pp. 8–13.