Defect defecting method based on wide frequency band ultrasonic phase array

Abstract

The invention discloses a defect defecting method based on a wide frequency band ultrasonic phase array, which is applied to an ultrasonic phase array transducer consisting of multiple array elements. The defect defecting method comprising the steps of: exciting by multiple array elements by adopting modulation codes, transmitting modified big-timewidth and big-bandwidth linear frequency modulation signals at a transmitting end, gathering the linear frequency modulation signals at a focal point and reflecting the signals; receiving the reflected signals at a receiving end by each array element and distributing the delayed and corrected signals within a same time window range; and implementing matched-filtering within a frequency domain according to the reflected signals received by each array element, coherently combining the matched-filtered signals within the frequency domain to obtain bandwidth signals within the frequency domain, and implementing inverse fast Fourier transform, thus obtaining time domain pulse compression signals. By virtue of the method, the bandwidth of the transmitted signals can be increased and the pulse compression signals with high resolution can be obtained, so that micro defects can be accurately detected.

Description

technical field [0001] The invention relates to acoustic detection technology, in particular to a defect detection method based on a broadband ultrasonic phased array. Background technique [0002] The ultrasonic phased array transducer is an array composed of multiple independent piezoelectric chips. According to certain rules and timing, the electronic system is used to control and excite each chip unit to adjust the position of the focus and the direction of concentration. The most notable feature of the transducer is that it can flexibly, conveniently and effectively control the sound beam shape and sound pressure distribution. The propagation of ultrasonic waves in the inspection medium attenuates exponentially relative to the distance. The ultrasonic signal received by the target far away from the array element is weak, and the signal-to-noise ratio of the echo signal carrying the defect signal is low, which leads to serious noise interference in the imaging of distant...

AI Technical Summary

Problems solved by technology

[0003] The purpose of the present invention is to solve the problems of narrow frequency band and low resolution of detection signals in traditional phased array signals, and improve the signal-to-noise ratio and resolution by increasing the bandwidth of the transmitted signal

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