Finite amplitude technology-based metal block closed crack detecting and positioning method

Abstract

The invention relates to a finite amplitude technology-based metal block closed crack detecting and positioning method. A sine wave is generated by a signal generator and is amplified by a power amplifier, the amplified sine wave excites an emission energy transducer to generate large-amplitude ultrasonic waves, inclined incident ultrasonic waves are transmitted to a metal block through a wedge as a detection signal and drive a closed crack in a metal block to periodically open and close in order to make sound wave be distorted and generate higher harmonic waves, most of a detection signal carrying the higher harmonic waves is reflected by a cracked surface, and a detection signal is received by an energy transducer and is displayed and stored through an oscilloscope. The metal block is connected with the energy transducer through the wedge, and the angle of incidence of the ultrasonic waves to the metal block can be changed by using the wedge with different inclined angles, so direct facing of the opening of the crack to the sound wave propagation direction can be avoided, and the crack detection probability is improved; and the transmit and receive energy transducers are arranged at the same side of the metal block, so detection is convenient.

Description

technical field [0001] The invention relates to a method for detecting and locating a closed crack of a metal block based on a finite amplitude method. Background technique [0002] Under the action of stress, the complete metal breaks locally and forms cracks in some weak parts. Cracks usually expand in metal use, which not only directly destroys the continuity of the metal, but also causes stress concentration at the end of the crack, which promotes crack growth in metal components under lower stress conditions, and eventually fractures. failure accident. Therefore, it is necessary to study a technology that can accurately detect the early plastic deformation and fatigue cracks of metal materials. Compared with other non-destructive testing technologies, ultrasonic non-destructive testing technology has many advantages such as accurate defect location, high detection sensitivity, and harmless to human body. However, the traditional linear ultrasonic testing technology ca...

AI Technical Summary

Problems solved by technology

However, due to the limitations of the principle, the traditional linear ultrasonic testing technology can only stay in the qualitative analysis stage, and cannot achieve quantitative evaluation and precise positioning of micro-cracks.

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