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A variable-mode magnetic concentrator Lamb wave electromagnetic-acoustic transducer

A magnetic concentration, transducer technology, applied in the directions of ultrasonic/sonic/infrasonic wave generation, fluid using vibration, etc., can solve the problem that the transducer cannot achieve a single mode excitation, etc.

Active Publication Date: 2021-05-25
BEIJING UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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, it is possible to simultaneously excite a single S in the plate 0 Modal vs Single A 0 Rare reports on modal Lamb wave electromagnetic acoustic transducers

Method used

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  • A variable-mode magnetic concentrator Lamb wave electromagnetic-acoustic transducer
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  • A variable-mode magnetic concentrator Lamb wave electromagnetic-acoustic transducer

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Embodiment Construction

[0035] The present invention will be further described below in conjunction with drawings and embodiments.

[0036] Based on the Lorentz force effect, a variable-mode magnetic concentrator type electromagnetic acoustic transducer is designed, and the transducer is used to excite a single-mode A on the aluminum plate. 0 Mode Guided Wave S 0 Modal guided waves.

[0037] The structure diagram of the variable-mode magnetic concentrator Lamb wave electromagnetic acoustic transducer is as follows: figure 1 , where a) the excitation mode is A 0 Schematic diagram of the transducer structure, b) the excitation mode is A 0 Schematic diagram of the time transducer structure; including a NdFeB magnet 1, a class A magnetic concentrator 2, a class B magnetic concentrator 3, and a double-layer variable-pitch folding coil 4 in a flexible circuit board. The detection object is an aluminum plate with a specification of 1000×1000×1 (unit: mm). Figure 6 is the ultrasonic guided wave group v...

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Abstract

The invention discloses a variable-mode magnetic concentrator-type Lamb wave electromagnetic acoustic transducer, which comprises a neodymium-iron-boron magnet, a class A magnetic concentrator, a class B magnetic concentrator, and a flexible circuit board. Double layer variable pitch return coil. Place the coil on the surface of the aluminum plate, and the upper surface of the magnetic concentrator and the NdFeB magnet are attracted and fixed directly above the coil. When a class A magnetic concentrator is selected, the lower surface of the magnetic concentrator is controlled to be placed on the center of the coil with a distance of d 1 On the coil, the main mode that can be excited is A 0 Modal guided wave; when the class B magnetic concentrator is selected, the lower surface of the control magnetic concentrator is placed on the center of the coil with a distance of d 2 On the coil, the excitable main mode is S 0 Modal guided waves. Through the frequency characteristic test, it is verified that the developed variable-mode magnetic concentrator Lamb wave electromagnetic acoustic transducer has good frequency response characteristics, and at the same time, the rationality of the transducer design is verified, and the structural health of the plate structure is realized. monitor.

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...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B06B1/04G01N29/34
CPCB06B1/04B06B1/045B06B2201/54G01N29/34
Inventor 刘增华邓黎明张永琛何存富吴斌
Owner BEIJING UNIV OF TECH
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