A nonlinear ultrasonic testing method for wind tower welds

Abstract

The invention discloses a non-linear ultrasonic detection method for a wind tower weld seam, relates to the technical field of non-destructive detection, and solves the technical problem that the existing easy-to-implement method has poor detection effect. The method of the present invention is to perform ultrasonic multi-point scanning on the target welding seam first, and collect the detection echo at each scanning point, and then perform short-time Fourier transform on the detection echo of each scanning point to obtain the echo of each scanning point Real-time spectrum curve; then calculate the spectrum similarity coefficient of the scanning points adjacent to the physical position, construct the spectrum similarity matrix according to the physical position relationship of each scanning point, and then obtain the spectrum similarity curve of the target weld; then according to the spectrum of the target weld Similarity curve to determine whether the target weld has defects. The method provided by the invention has the advantages of accurate positioning, high sensitivity, good intuitiveness of defect determination and the like.

Description

technical field [0001] The invention relates to non-destructive testing technology, in particular to a non-linear ultrasonic testing method for wind tower welds. Background technique [0002] The height of the wind tower of the grid-connected wind turbine is more than 40 meters, and the load nacelle weighs dozens of tons. The wind tower is welded by tower tubes of different diameters and flange bases, and the number of welds is as many as hundreds. The key technical issue to ensure the reliability and stability of the wind tower support is to ensure the reliability and consistency of the wind tower weld seam welding. Since welding is a special physical metallurgical process, the control of process parameters, changes in material properties and human factors in the process will cause different degrees and types of defects in welded components, which will have a very adverse impact on the service life. Therefore, before the wind tower is put into use, it is necessary to condu...

AI Technical Summary

Problems solved by technology

However, due to the small amplitude of high-order harmonics, nonlinearities such as system equipment and coupling media, and random noise have a great impact on measurement accuracy

According to the current relevant literature, with the help of high-energy pulse amplifiers and high-precision filters, the amplitude of the second or higher harmonics excited by defects can only be accurately measured under laboratory conditions, which restricts the use of nonlinear parameters to detect material defects. and the practical application of distortion, this detection method is basically impossible to implement under normal conditions

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