Method for non-contact wave velocity extraction of Lamb wave of single-layer board

Abstract

The invention discloses a method for the non-contact wave velocity extraction of a Lamb wave of a single-layer board, and the method belongs to the technical field of nondestructive examination. The requirement of a novel material cannot be met by adopting a method destructing mechanical properties for an ultra-thin glass plate, a thin-layer ceramic material and the like. In the nondestructive examination for mainly measuring the wave velocity of an acoustic wave, a V(z) curve formed by the interference of a leaky Lamb wave and a directly reflected wave, namely a longitudinal wave, comprises much information at the characteristic aspect of the material, such as a thickness, a density, a Young modulus, a shear modulus and the like. The method is based on a defocusing measurement system; a wide-frequency pulse is utilized as an excitation source; an ultrasonic wave comprising a plurality of frequency components is received; and the V(z) curve of the material and an oscillating period thereof are obtained through an improved two-dimensional Fourier transform technique, so as to achieve the wide-frequency continuous extraction of the wave velocity of the Lamb wave. By using the method, the quick and accurate wave velocity extraction can be carried out on the Lamb waves of different materials; a multimode wave velocity can be extracted; the wave velocity can be extracted in a wide frequency range; and a single-frequency point-by-point way is replaced.

Description

technical field [0001] The invention belongs to the field of non-destructive testing, and in particular relates to a wave velocity extraction method for a single-layer plate Lamb wave. Background technique [0002] With the continuous development of material science, various functional materials are emerging, such as thin film materials and ultra-thin plate materials, which often show brittle characteristics. Therefore, traditional destructive mechanical performance testing methods such as traditional tensile Will not be able to meet the demand for new materials. In the non-destructive testing that mainly measures the acoustic wave velocity, the V(z) curve formed by the interference of the leaked Lamb wave and the direct reflected wave contains a lot of information on the microstructure of the material, and the ultrasonic microscope is used as a wave velocity measurement tool. It can be applied to the mechanical properties of materials such as elastic modulus, residual stre...

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to solve the problem of extracting Lamb wave broadband continuous wave velocity of isotropic thin plate materials, and propose an advanced material wave velocity extraction method

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