Omnidirectional high-order Lamb wave mode electromagnetic acoustic sensor based on variable-angle magnetic concentrator
A concentrator, variable angle technology, applied in the direction of material analysis, instruments, scientific instruments, etc. using sound waves/ultrasonic waves/infrasonic waves
Active Publication Date: 2020-01-17
BEIJING UNIV OF TECH
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Problems solved by technology
At present, there are few reports on sensors that can excite omnidirectional high-order Lamb wave modes in the plate
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[0029] The present invention will be further described below in conjunction with drawings and embodiments.
[0030] Based on the magnetostrictive effect, an omnidirectional A 1 Modal electromagnetic acoustic sensor, which is used to excite a single circumferentially consistent Lamb wave A on an aluminum plate 1 modal.
[0031] Omnidirectional type A based on variable angle magnetic concentrator 1 The schematic diagram of the structure of the modal electromagnetic acoustic sensor is shown in figure 1 As shown, it includes a semicircular NdFeB magnet 1; a semicircular variable-angle magnetic concentrator 2; The detection object is an aluminum plate with a specification of 1000×1000×1 unit: mm. Figure 6 is the ultrasonic guided wave group velocity and phase velocity dispersion curve of the aluminum plate above. When the wavelength λ is determined, the resulting A can be uniquely determined 1 modal frequency. When the semi-circular turnback coil 3 in the flexible circuit b...
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The invention discloses an omnidirectional high-order Lamb wave mode electromagnetic acoustic sensor based on a variable-angle magnetic concentrator. When the sensor works, a semicircular annular folding coil carrying high-frequency current induces induced eddy current which is distributed in a semicircular annular manner and is opposite in direction in an aluminum plate, permanent magnets providea static magnetic field perpendicular to the aluminum plate, and the direction of the static magnetic field is changed by the semicircular variable-angle magnetic concentrator to generate an alternately distributed Lorentz force in the aluminum plate based on the Lorentz force transduction mechanism, so that the excitation of a single high-order Lamb wave mode in the aluminum plate is realized. It is verified by experiments that the developed electromagnetic acoustic sensor can excite a single high-order Lamb wave in the aluminum plate, the electromagnetic acoustic sensor has relatively goodfrequency response characteristics, the developed electromagnetic acoustic sensor can excite the high-order Lamb wave mode propagated in the circumferential direction, the long-distance defect detection of the plate structure can be realized, and the electromagnetic acoustic sensor has a great application value and potential in the field of structural health monitoring and non-destructive evaluation.
Description
technical field [0001] The invention is an omnidirectional high-order Lamb wave mode electromagnetic acoustic sensor based on a variable-angle magnetic concentrator, which belongs to the field of ultrasonic nondestructive testing, and can excite a single high-order Lamb wave mode propagating along a specific direction in a metal plate structure state. 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 use of metal plate structures, it is necessary to carry out non-destructive testing on them. As a fast and efficient nondestructive testing method, ultrasonic guided wave technology has been widely used in nondestructive evaluation and health monitoring of various engineering structures such as plates, pipes and rods...
Claims
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Login to View More IPC IPC(8): G01N29/24G01N29/34
CPCG01N29/2412G01N29/34
Inventor 刘增华刘泽华李佳奇赵欣张永琛何存富吴斌
Owner BEIJING UNIV OF TECH