Research And Application Of Ultrasonic Nondestructive Testing And Detection Algorithm For Metallic Materials

With the rapid development of science and technology,metal castings have been used in many fields,such as aviation,aerospace,railways,and petroleum.In the fields of aerospace and other fields,the evaluation of the safety and availability of metal aluminum castings has become indispensable.A job.Ultrasonic non-destructive testing as a detection method has been widely used due to its good penetration and directivity.Ultrasonic non-destructive testing produces structural noise and unstructured noise during the flaw detection process,forming a non-stationary ultrasonic signal.This non-stationary ultrasonic signal has a certain influence on the extraction of useful information in the detection signal and affects the subsequent detection work.According to the characteristics of ultrasonic detection signals,the paper processed and analyzed the ultrasonic signals obtained by actual measurement,and compared them by wavelet transform and empirical mode decomposition.Compared with wavelet transform,compared with wavelet transform,the empirical mode decomposition denoising algorithm has less waveform distortion when processing signals and is more suitable for denoising of echo signals of metal castings.The empirical mode decomposition of the interval-threshold noise reduction algorithm is studied and analyzed.In the process of noise reduction,the empirical mode decomposition method will be used to eliminate useful small information,especially in the interval threshold noise reduction process,the soft interval threshold is used.In the function,there is a constant error in the detail information before and after processing;when the hard interval threshold function is processed,oscillation occurs at the discontinuity point,and an improved interval threshold function noise reduction algorithm is proposed.The research analysis and simulation verification results showthat when Gaussian white noise with more than 10 dB is added to the test signal,the signal after processing by the improved algorithm is improved compared with the signal before and after improvement,the signal-to-noise ratio is improved by approximately 1dB,the root mean square error is improved,and the signal waveform is also relatively high.Smooth,less distortion.Finally through the test,the defect is located and calculated,and the error is analyzed,and the minimum emission voltage is determined.The experimental results show that the improved algorithm can meet the requirements of engineering applications.