超声检测数字信号处理方法研究

Research on Digital Signal Processing Method of Ultrasonic Testing

以钛阶梯试块为研究对象采集超声信号,以不同的信号处理方法分别从时域和时频域处理采集信号,通过短时傅里叶时频二次分析和小波时频分析分别做出频率集中处的能量分布图,并根据始波和一次底波能量峰值的采样点数差值计算其时间间隔,根据已知声速测量试块的厚度;通过小波去噪和经验模态分解对去噪后的信号找出始波和一次底波峰值,并根据其采样点数差值计算其时间间隔,根据已知声速测量试块厚度。通过对信号处理后的波形测量试块厚度比较不同超声信号处理方法。

The ultrasonic signal is collected from a titanium step test block,and the signal is processed in the time domain and the time-frequency domain by different signal processing methods,and the energy distribution at the frequency concentration is made by short-time Fourier time-frequency secondary analysis and wavelet time-frequency analysis respectively,and the time interval is calculated according to the difference in the number of sampling points between the peak of the initial wave and the peak of the primary bottom wave,and the thickness of the test block is measured according to the known sound speed.The initial and bottom wave peaks are identified by wavelet denoising and empirical modal decomposition of the denoised signal,and the time interval is calculated from the difference between their sampling points and the thickness of the test block is measured according to the known sound velocity.The thickness of the test block is measured by the waveform after signal processing and compared with different ultrasonic signal processing methods.