Laser sonic surface wave stress test system

A surface acoustic wave and stress testing technology, which is applied in the analysis of solids using sound waves/ultrasonic waves/infrasonic waves, can solve the problems of high cost, low sensitivity of optical interferometers, and the inability to measure the two-dimensional distribution of surface stress, etc., and achieve simple structure , system cost reduction, and the effect of improving detection sensitivity

Inactive Publication Date: 2008-10-08
NANJING UNIV OF SCI & TECH
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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 di...

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  • Laser sonic surface wave stress test system

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Embodiment Construction

[0009] The specific structure of the present invention will be described in further detail below in conjunction with the accompanying drawings.

[0010] Referring to the accompanying drawings, the laser surface acoustic wave stress testing system made according to the present invention mainly consists of a pulse laser 1, a beam splitter 2, a triangular prism 4 and a cylindrical convex lens 5 to form an ultrasonic surface wave excitation part, and consists of a PVDF piezoelectric film 9 and a high frequency The preamplifier 10 constitutes an ultrasonic surface wave detection section. Pulse laser 1 is a short pulse laser with an output wavelength of 1064 nm, a pulse width of 10 ns, and a single pulse output energy of 70 mJ. The beam splitter 2, the triangular prism 4 and the cylindrical convex lens 5 are sequentially arranged on the same optical path; a photodiode 11 is arranged on the reflection optical path of the beam splitter 2, which receives a small part of the reflected l...

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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...

Claims

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Application Information

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IPC IPC(8): G01N29/07
Inventor 沈中华石一飞倪晓武倪辰荫严刚
Owner NANJING UNIV OF SCI & TECH
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