Variable-mode magnetic concentrator type lamb wave electromagnetic acoustic transducer

Abstract

The invention discloses a variable-mode magnetic concentrator type lamb wave electromagnetic acoustic transducer. The variable-mode magnetic concentrator type lamb wave electromagnetic acoustic transducer comprises a neodymium iron boron magnet, an A-type magnetic concentrator, a B-type magnetic concentrator and a double-layer variable-spacing inflection coil in a flexible circuit board. The coilis positioned on the surface of an aluminum plate; the upper surface of a magnetic concentrator and the neodymium iron boron magnet are attracted and then fixed right above the coil; when the A-type magnetic concentrator is selected, the lower surface of the magnetic concentrator is controlled to be positioned on the coil with the coil center distance of d1, thus exciting a guided wave with a mainmode of A0; and when the B-type magnetic concentrator is selected, the lower surface of the magnetic concentrator is controlled to be positioned on the coil with the coil center distance of d2, and the guided wave with the main mode of S0 can be excited. The frequency characteristic test verifies that the developed variable-mode magnetic concentrator type lamb wave electromagnetic acoustic transducer has high frequency response characteristic, simultaneously verifies the rationality of transducer design, and realizes the structural health monitoring of a plate structure.

Description

technical field [0001] The invention is a variable-mode magnetic concentrator type Lamb wave electromagnetic acoustic transducer, which belongs to the field of ultrasonic non-destructive testing, and can only replace different magnetic concentrators without changing a series of parameters such as coils, magnets and excitation frequencies. In this case, guided waves of different modes are excited in the plate structure. Background technique [0002] Sheet metal structures are widely used in aerospace, civil engineering, machinery and other fields. In the process of production and use, the metal plate structure will inevitably be damaged, which greatly reduces the service life of the material. In order to ensure the safety of the metal plate structure, it is necessary to carry out non-destructive testing on the metal plate. In the traditional ultrasonic testing technology, the piezoelectric ultrasonic technology is an important part of the traditional ultrasonic testing tech...

AI Technical Summary

Problems solved by technology

S 0 Modal EMAT aspect present, the omnidirectional S 0 The modal EMAT has received more attention and research. Wilcox et al. established the theoretical model of the omnidirectional EMAT in the plate. Based on the Lorentz force mechanism, the annular compactly wound helical coil coil is designed and manufactured to effectively excite the EMAT in the plate. S with the same directivity within 360° 0 Modal EMAT, but the transducer cannot be excited by a single mode

Currently, a single S can be excited simultaneously in the board 0 Modal vs Single A 0 Rare reports on modal Lamb wave electromagnetic acoustic transducers

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