Ultrasonic phased array high-efficiency phase shift imaging method for multilayer structure hole defects

Abstract

The invention provides an ultrasonic phased array high-efficiency phase shift imaging method for hole defects of a multilayer structure. The ultrasonic phased array high-efficiency phase shift imaging method comprises the following steps: (1) converting collected full-matrix data of the multilayer structure into a frequency wave number domain through three-dimensional fast Fourier transform; (2) extrapolating a surface wave field of the multi-layer structure to an upper interface of any non-traversed layer in the multi-layer structure to obtain wave field information of the non-traversed layer; (3) according to the obtained wave field information, focusing imaging is carried out on the non-traversed layer in a frequency wave number domain; and (4) repeating the steps (2) and (3) until all layers are traversed to obtain an imaging result of the multi-layer structure. According to the imaging method, only two operators of superposition and two-dimensional Fourier transform are adopted, and a cross-correlation operator in frequency domain phase shift is not needed, so that the memory requirement and the calculation complexity are greatly reduced, the calculation time is shortened, and the imaging efficiency is improved; and the imaging resolution is high.

Description

technical field [0001] The invention belongs to the technical field of detection methods, and in particular relates to an ultrasonic phased array high-efficiency phase shift imaging method for hole defects in a multilayer structure. Background technique [0002] To combine the advantages of different materials, such as high strength, light weight, corrosion resistance, durability and flexibility, multilayer structures are used in construction, electronics and aerospace. However, due to the complicated manufacturing process and severe service process, internal void defects are very common in these products, which can greatly impair the mechanical properties of the products and shorten the service life. Common non-destructive testing methods for void defects in composite products are infrared (IR) thermal imaging and X-ray tomography. Infrared thermal imaging captures the local high temperature at the void defect to determine the defect location, but cannot determine the depth...

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Problems solved by technology

Compared with RMS-based TFM, EPSM imaging results in improved accuracy and resolution, but at a lower efficiency

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