Experimental Research on the Evaluation of Metal Sheet Damage Using Electromagnetic Acoustic Resonance

Experimental Research on the Evaluation of Metal Sheet Damage Using Electromagnetic Acoustic Resonance

Deng Mingxi

(College of Logistics Engineering, Chongqing, 401331)

Abstract: Based on a brief analysis of the basic experimental principles of the Electromagnetic Acoustic Resonance (EMAR) method, with the help of the Ritec SNAP 5000 ultrasonic measurement system, the transverse wave resonance spectra of several metal plates were measured using the EMAR method. The experimental results show that it is feasible to use EMAR method for non-destructive evaluation of metal sheet damage.

Keywords: electromagnetic acoustic resonance; resonance spectrum; metal plate; damage

CLC number: O 0422.6 Document identification code: A

Experimental Study of Evaluation of Damage in Metallic Plates Using Electromagnetic Acoustic Resonance Technique

DENG Ming-xi

(Logistics Engineering University, Chongqing 401331, China)

Abstract: The principle of the electromagnetic acoustic resonance (EMAR) technique has been briefly analyzed in this paper. Based on the Ritec SNAP 5000 ultrasonic measurement system, the shear wave EMAR spectra of some metalic plates have been measured. The experimental results indicate that it is feasible to nondestructively evaluate damage in metalic plates with the EMAR technique.

Key words: electromagnetic acoustic resonance (EMAR), resonant spectrum, metalic plates, damage

1 Introduction

It is widely applied to metal plate components in the field of practical engineering. Various forms of load will degrade its mechanical properties and accurately and non-destructively evaluate the damage of metal plates, which is of great practical significance for ensuring its safety and reliability. . So far, ultrasonic lam wave and acoustic emission technologies have been used for non-destructive evaluation of sheet damage. However, from the perspective of actual use effect, it is still necessary to develop a non-destructive evaluation method for metal plate damage that is not limited by the interface acoustic coupling conditions, the measurement method is relatively simple, and the measurement is fast and accurate; the electromagnetic acoustic resonance (EMAR) method can meet the above requirements [ 1,2].

EMAR uses electromagnetic electromagnetic transducer (EMAT) to excite and receive appropriate ultrasonic mode inside the metal plate, and then obtain the resonance spectrum of the ultrasonic wave in the metal plate. The main advantage of using EMAT is non-contact; more importantly, the resonance spectrum obtained by the EMAR method completely eliminates the influence of the piezoelectric transducer and acoustic coupling layer on the resonance spectrum in the traditional method, and the resulting (free) resonance spectrum Only depends on the mechanical properties of the metal plate structure. In addition, because ultrasonic energy does not penetrate into EMAT, it can only be reflected back and forth inside the metal plate. Therefore, compared with the traditional method of measuring the resonance spectrum with a piezoelectric transducer, EMAT can receive a greater number of reflected ultrasound time domain Pulse signal; even if the conversion efficiency of EMAT is low, the multiple reflection ultrasonic time-domain pulse signals in the resonance state can be received in a one-transmit-one-receive mode, and a very obvious resonance spectrum can still be obtained.

Existing research results show that the EMAR method can better perceive changes in the microstructure of materials [1,2]. In this paper, based on a brief description of the basic experimental principles of EMAR, a pair of shear wave EMAT is used, with the help of Ritec SNAP 5000 ultrasonic measurement system [3], the transverse wave resonance spectrum curves of several metal plates are measured by EMAR method. The experimental results show that the EMAR method can more sensitively reflect the damage of the metal sheet, and has the characteristics of simple operation process, online measurement and good measurement consistency.

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