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Method for calculating laser surface acoustic wave frequency dispersion curve

A surface acoustic wave and dispersion curve technology, applied in the field of non-destructive testing, can solve the problems of inaccurate dispersion curve, low resolution of CWT time-frequency map, etc., and achieve the effect of high accuracy

Inactive Publication Date: 2020-03-06
TIANJIN UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

But the resolution of the CWT time-frequency diagram is low, and it is easy to expand in the frequency direction, so the resulting dispersion curve is still inaccurate

Method used

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  • Method for calculating laser surface acoustic wave frequency dispersion curve
  • Method for calculating laser surface acoustic wave frequency dispersion curve
  • Method for calculating laser surface acoustic wave frequency dispersion curve

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[0024] Certain terms are used, for example, in the description and claims to refer to particular components. Those skilled in the art should understand that hardware manufacturers may use different terms to refer to the same component. The specification and claims do not use the difference in name as a way to distinguish components, but use the difference in function of components as a criterion for distinguishing. As mentioned throughout the specification and claims, "comprising" is an open term, so it should be interpreted as "including but not limited to". "Approximately" means that within an acceptable error range, those skilled in the art can solve the technical problem within a certain error range and basically achieve the technical effect.

[0025] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "horizontal" etc. are based on t...

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Abstract

The invention belongs to the technical field of nondestructive testing, and particularly relates to a method for calculating a laser surface acoustic wave frequency dispersion curve. The method comprises the following steps of exciting complex frequency surface acoustic wave on a surface layer of a film / matrix by using pulse laser, picking up vertical displacement signals of the surface acoustic wave at different positions, performing synchronous compression wavelet transform on the vertical displacement signals to obtain a time-frequency distribution graph, and extracting time information ofenergy peak values at different frequencies in the time-frequency distribution graph so as to calculate and obtain the laser surface acoustic wave dispersion curve. The method has high accuracy of calculating the laser surface acoustic wave frequency dispersion curve.

Description

technical field [0001] The invention belongs to the technical field of nondestructive testing, and in particular relates to a method for calculating the dispersion curve of laser surface acoustic waves. Background technique [0002] Surface acoustic waves (SAW) were discovered by Rayleigh in 1885 while studying seismic waves. It is an elastic wave that propagates along a surface with a penetration depth of about one wavelength. The generation of a large number of piezoelectric materials in the 20th century provided the necessary material basis for the study of surface acoustic waves, and gradually gained practical application. The generation and development of lasers have broken through the limitation that only piezoelectric materials can generate surface acoustic waves. Since then, Laser Surface Acoustic Wave (LSAW) has been gradually applied to the study of surface properties, and has become a research hotspot in nondestructive testing. [0003] The relative change of s...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N29/04G01N29/44G01L1/25
CPCG01N29/041G01N29/4472G01L1/255G01N2291/0423
Inventor 林滨刘再蔚梁小虎杜安尧
Owner TIANJIN UNIV