Extraction of Weak Pulse in Crack Inspection Based on Stochastic Resonance

Acoustic method is widely used in industrial pipe crack inspection. A series of sound wave transmits through the pipe. When there is a crack at some position of the pipe, a sound pulse containing the position information of the crack will emerge in the received sound wave signal. Due to the environmental noise or the minority of the crack, the amplitude of sound pulse is usually very weak. It is important to extract the weak sound pulse from the noisy signal. Stochastic resonance (SR) is a kind of nonlinear phenomenon occurred in special nonlinear system subjected to noise and other excited signal, which is reported useful in enhancing digital signal transmission and detecting weak periodic signal. In the paper, the model of SR is applied to the weak sound pulse extraction from the received sound signal. We detail the principle and algorithm of SR model for extracting weak a periodic pulse. Simulation scheme and results are presented. Actual crack inspection experiments of PVC pipe with small crack are carried out using SR model to extract the weak sound pulse. The results show that SR provides a novel and effective way for weak sound pulse extraction in pipe crack inspection.