Abstract
The low energy transition efficiency of electromagnetic ultrasonic transducer (EMAT) is a common problem in practical application. For the purpose of enhancing the amplitude of the received signal, an improved double-coil bulk wave EMAT is proposed for the thickness measurement of metallic block. This new configuration of magnets consists of a solid cylindrical magnet and a ring-shaped magnet encircling the outer side of the solid cylindrical one. A double-coil was applied instead of a single spiral-coil. Numerical simulations were performed to analyze and optimize the proposed configuration of the EMAT by the 2-D axisymmetric finite element model (FEM). The experiment effectively verifies the rationality of the new configuration and the feasibility of improving the signal strength.
Highlights
Nondestructive testing (NDT) is an indispensable tool for industrial development, and its method mainly includes ultrasonic testing (UT), radiation testing (RT), magnetic particle testing (MT), liquid penetration testing (PT) and AC field measurement (ACFMT)
Compared with conventional piezoelectric transducers, the poor energy efficiency is the predominant drawback of Electromagnetic acoustic transducer (EMAT), which leads to the low signal to noise ratio (SNR) of the ultrasonic signal [13,14,15,16]
The main work of this paper is to propose an improved configuration related to cylindrical magnet to strengthen the magnetic field of the spiral-coil EMAT for generation and detection of the bulk waves, which is mainly used to measure the thickness of the metallic plate
Summary
Nondestructive testing (NDT) is an indispensable tool for industrial development, and its method mainly includes ultrasonic testing (UT), radiation testing (RT), magnetic particle testing (MT), liquid penetration testing (PT) and AC field measurement (ACFMT). There are substantial conspicuous improvements in the performance and transduction efficiency of EMATs, such as the application of high-frequency pulse generator and low-noise receiver, the introduction of phased array and the digital signal processing [18,19]. These methods will make electronic devices bulky. The main work of this paper is to propose an improved configuration related to cylindrical magnet to strengthen the magnetic field of the spiral-coil EMAT for generation and detection of the bulk waves, which is mainly used to measure the thickness of the metallic plate.
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