Ultrasonic detection has been widely used as an important means of rail flaw detection.However,the signal-to-noise ratio(SNR)of flaw detection data obtained using traditional ultrasonic transmitting and receiving methods is often low due to ghost echo and transducer mutual interference.To address this issue,the influence mechanism of ghost echo and transducer mutual interference is discussed according to the characteristics that the frequency of ultrasonic excitation of piezoelectric wafers in ultrasonic transducer coincides with that of the high-voltage pulse excitation of piezoelectric wafer in the loaded transducer.The double-beat orthogonal code technology is studied,high voltage pulse excitation signal with orthogonal frequency is applied to piezoelectric wafer of ultrasonic transducer to generate ultrasonic transmitting signal with orthogonal frequency.The corresponding decoding method is employed to suppress ghost echoes and the transducer mutual interface,thereby enhancing the SNR of detection data.An experimental platform for the ultrasonic system is built,and the A-display and B-display test data from national standard flaw detection are analyzed.The results show that for A-display data,the suppression of ghost echoes and the transducer mutual interference by the double-beat orthogonal code is more effective than that of the damaged signal,with an average suppression ratio of 10.39 dB.For B-display data,the damage detection rate is 100％when using the double-beat orthogonal code mode,and the ghost wave and the transducer mutual interference elimination is 100％.Compared with traditional ultrasonic transmitting and receiving methods,the double-beat orthogonal code ultrasonic transmitting and receiving technology can eliminate the influence of ghost echoes and the transducer mutual interference,improve the SNR of ultrasonic signal,and reduce the misjudgment and missed detection of injury,all without compromising the damage detection rate.
维普
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