Analysis and application of weak guided wave signal detection based on double Duffing oscillators

In this study, a double chaotic detection system was proposed to identify the weak defect echo signal caused by small defects during ultrasonic guided wave (UGW) nondestructive testing of pipelines. By identifying the amplitude and time of flight (ToF) of defect echoes, minor defects in early damage identification of pipelines were quantitatively detected. First, the Duffing oscillator detection system parameters were determined using the displacement bifurcation diagram and a Poincare map. Thereafter, the UGW signal was added to the driving force of the Duffing system. The influence characteristics of UGWs on Duffing systems were deduced in detail, and the identification method of the UGW amplitude was obtained. Two Duffing chaotic systems with specific frequencies were constructed, and the ToF of the UGW was determined from the compensation phase. Simulation and experimental results showed that this method could identify the size and ToF of UGWs simultaneously. Even when the signal-to-noise ratio (SNR) was-20 dB, the identification error of the amplitude was only 8 %, which indicated that the detection result was acceptable. Pipeline defects identified using this method, in which the identification error of the defect size was below 7 %, and the defect location identification error was below 6 %, indicated that the method could effectively improve the sensitivity of UGWs in the detection of small defects in a pipeline. This provided a guarantee for early damage identification of a pipeline.