A Polarity Weighted Vector Total Focus Imaging Method for Quantitative Identification of Crack-like Defects

Abstract

The invention discloses a polarity weighting vector fully focusing imaging method for identifying crack type defects quantitatively and belongs to the technical field of non-destructive testing. The vector fully focusing imaging principle based on polarity weighting comprises the steps of constructing multiple sub arrays in an array transducer, and calculating a unit direction vector and a polarity weighting imaging amplitude matrix thereof, at each imaging point, of each sub array, so that a characteristic vector, at each imaging point, of each sub array is obtained; compositing all the sub array characteristic vectors obtained through calculation, so that a composite characteristic vector is obtained; conducting global treatment on the amplitude of the composite characteristic vector, in other words, making the amplitude of the composite characteristic vector be equal to the amplitude, at any focus point, of obtained polarity weighting imaging of the whole array, wherein the amplitude vector, at any focus point, of the whole array can be obtained; finally, extracting a local vector diagram of a target defect according to the defect position, and determining the direction of the target defect by means of the direction of the direction of the vector in the local vector diagram.

Description

technical field [0001] The invention relates to a method for identifying the direction of crack defects based on polarity-weighted vector total focus imaging. The method relates to the direction identification technology for crack defects and belongs to the technical field of non-destructive testing. Background technique [0002] Metal structures are widely used in aerospace, shipbuilding, machinery manufacturing and other industrial fields, such as spacecraft components, ship and submarine components, large pressure vessels, large forgings, steel plates for bridges, etc. Due to the influence of pressure, temperature, external load impact, stress concentration, chemical corrosion and other factors in the process of processing, manufacturing and using metal structures, it is very easy to produce cracks, holes, corrosion and other defects on the surface and inside of the structure. If there are defects and take corresponding measures, it is likely to cause serious consequences...

AI Technical Summary

Problems solved by technology

[0004] The 2009 journal paper "Phase coherence imaging" analyzed the polarity of the array data (the sign bit of the aperture data), and proposed an ultrasonic array imaging method that suppresses side lobes and grating lobes and improves imaging resolution—polarity Weighted imaging method, which is easy to operate and has better imaging effect, but the polarity weighted imaging method can accurately locate defects such as cracks in the structure, but cannot identify the direction of crack defects

Because the conventional vector total focus imaging method only uses the signal amplitude information, its imaging quality is greatly affected by noise, side lobes and grating lobes, etc., the signal-to-noise ratio and resolution are low, and the quantitative identification ability of defects is limited. Based on the amplitude and phase information of matrix data, a polarity-weighted vector omni-focus imaging method is proposed to realize the direction recognition of crack-like defects in metal structures

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