Laser sonic surface wave stress test system

Abstract

The invention discloses a laser acoustic surface wave stress test system, which is mainly comprises an ultrasound surface wave excitation part composed of a short-pulse laser, a spectroscope, a triple prism and a cylindrical convex lens, and an ultrasound surface wave detection part composed of a PVDF piezoelectric film and a high-frequency pre-amplifier. The invention uses the short-pulse laser to generate a high-frequency ultrasound surface wave on the surface of the samples to be tested, a stress value is obtained according to the principle of acoustic elasticity, the PVDF piezoelectric film is served as the receiver of the ultrasound surface wave, fast two-dimensional scanning is realized on the surface of the samples in the way that the PVDF piezoelectric film is fixed, the excitation source and the samples to be tested are in two-dimensional translation motion, the obtained ultrasound surface wave signals are transmitted to an electronic computer, and the measurement of the stress distribution on the surface and the sun-surface of the samples is realized through fast computing and processing by programming according to the principle of acoustic elasticity. The system has the advantages of simple structure and low cost, which can be widely used in the stress distribution measurement on the surface and the sun-surface of metal materials.

Description

a technical field [0001] The invention relates to a stress test system, in particular to a laser surface acoustic wave stress test system applied to the stress distribution test on the surface and subsurface of metal materials. 2. Background technology; [0002] The method of measuring the stress of materials by ultrasonic method has been developed since the 1940s. According to the principle of acoustoelasticity, that is, when there is a stress distribution in the material, the propagation speed of the ultrasonic wave is related to the magnitude of the stress, and the stress value can be indirectly measured by measuring the propagation speed of the ultrasonic wave. The traditional ultrasonic method uses an acoustic transducer as the ultrasonic excitation and receiving device. The ultrasonic frequency excited by this method is low, so the spatial resolution is low, and only the integral effect of the stress on the ultrasonic propagation path can be given, and the acoustic Th...

AI Technical Summary

Problems solved by technology

However, this system only scans one-dimensionally in the depth direction of the sample, and can only obtain the distribution of stress in the depth direction, but cannot measure the two-dimensional distribution of surface stress. At the same time, the optical interferometer used for detection has low sensitivity and high cost. , which is not conducive to the promotion and application of the test system

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