Air-coupled ultrasonic testing method for determining elastic modulus of material

Abstract

The invention discloses an air-coupled ultrasonic testing method for determining the elastic modulus of a material. The air-coupled ultrasonic testing method comprises the following steps: solving according to a guided wave frequency dispersion relational expression of a symmetric mode and an anti-symmetric mode, thus obtaining a first theoretical frequency dispersion curve of guided waves; experimentally testing a guided wave wavelength in a to-be-tested board under a given frequency thickness product by using the first theoretical frequency dispersion curve, thus obtaining a first actually measured frequency dispersion curve of the guided waves; obtaining a change rate curve of a guided wave phase velocity along with the elastic modulus and a change rate curve of the guided wave phase velocity along with a poisson ratio by calculation; screening out multiple pairs of calculation point pairs according to the change rate curves of the guided wave phase velocities; aiming at every point in the calculation point pairs, repeating step one and step two by utilizing the elastic modulus and the poisson ratio which correspond to every point, thus obtaining a second actually measured frequency dispersion curve; solving the elastic modulus of a to-be-tested material by utilizing minimum square of phase velocity deviation and an optimization algorithm according to the second actually measured frequency dispersion curve. According to the air-coupled ultrasonic testing method disclosed by the invention, nondestructive measurement on the elastic modulus of the material can be realized, and a measurement result is accurate.

Description

technical field [0001] The invention relates to the technical field of ultrasonic nondestructive testing, in particular to an air-coupled ultrasonic testing method for determining the elastic modulus of materials. Background technique [0002] Nondestructive Testing (NDT) is a technology that detects its performance, quality, and internal defects without destroying or damaging the object under test. Among the existing non-destructive testing methods, conventional methods include radiography (RT) method, ultrasonic testing (UT) method, penetrant testing (PT) method, magnetic particle testing (MT) method, eddy current testing (ET) method, and of course Microwave detection method, potential detection method, etc. [0003] Ultrasonic testing (UT) is to use the ultrasonic wave to propagate in the material to be tested, the acoustic characteristics of the material and the change of the internal structure have a certain influence on the propagation of the ultrasonic wave, and to u...

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Problems solved by technology

[0005] The technical problem to be solved by the present invention is to overcome the defect of the method for measuring the elastic modulus of the material through the guided wave dispersion characteristic in the prior art that is not mature, and propose a method for determining the elastic modulus of the material air-coupled ultrasonic testing method

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