A Thickness Estimation Method Under the Condition of Signal Mixing in Ultrasonic Pulse Echo Thickness Measurement

Abstract

The invention discloses a thickness estimation method under the condition of signal aliasing in ultrasonic pulse echo thickness measurement, which comprises: selecting standard test blocks with different thicknesses in the target thickness estimation interval as standard thickness reference points; adopting the ultrasonic pulse echo method multiple times Collect the pulse-echo time-domain signals of standard test blocks of different thicknesses, perform fast Fourier transform after windowing to generate spectrograms; cut the spectrograms of each standard test block into a certain frequency range and use them as training sample sets to input into convolutional neural network The recognition model is formed by training in the method; the frequency spectrum of the echo of the workpiece to be tested is input into the recognition model to obtain the spectral similarity between the workpiece to be tested and each standard test block, which is used as the weight for estimating the thickness of the workpiece to be tested. The present invention is based on the subtle frequency shift changes of the main lobe of the spectrum diagram and the side lobes of each harmonic under different thicknesses of the ultrasonic pulse echo, and uses a convolutional neural network to identify the spectrum diagram, which can realize the echo time domain signal In the case of aliasing, estimate the thickness of the workpiece to be measured.

Description

technical field [0001] The invention discloses a thickness estimation method under the condition of signal aliasing in ultrasonic pulse echo thickness measurement, belonging to the technical field of ultrasonic nondestructive testing. Background technique [0002] In large-scale industries such as machinery manufacturing, aerospace, and automobile manufacturing, the workpieces produced need to be used in harsh environments for a long time, and defects such as damage will pose a serious threat to production safety. Therefore, the requirements for the remaining thickness of workpieces are becoming more and more stringent. , Ultrasonic non-destructive thickness measurement has a wide range of applications. [0003] In the traditional application of ultrasonic thickness measurement, the TOF (Time of Flight) of the acoustic wave is mainly measured. Commonly used methods include threshold method, peak value method, envelope method, curve fitting method and cross-correlation method...

AI Technical Summary

Problems solved by technology

However, in the thickness measurement of thin parts, the time-domain signals of each echo have been seriously aliased due to the poor accuracy of the probe and the sharp drop in the signal-to-noise ratio of the echo after multiple reflections. The traditional TOF measurement method will produce relatively large big error

Images