Structural Damage Identification Based On Correlation Coefficient Of Lamb Wave Signal

In this paper, the damage identification methods based on the signal correlation coefficient were studied. An effective signal automatic extraction algorithm was proposed. Based on the algorithm, the damage identification methods with baseline and without baseline were developed based on the signal correlation coefficient. Further, the representation method of the damage degree was also explored.Firstly, a method of multiple damage locations identification and imaging based on signal correlation coefficient was studied. The detected key area in the structure is divided into several subregions, and the effective signal containing the structural damage information are automatically extracted from the entire Lamb wave responses received. Subsequently, the damage indexes of every subregion based on the correlation coefficient are evaluated by using effective signal automatic extraction algorithm. Eventually, the damage locations identification and imaging are performed using the reconstruction algorithm for probabilistic inspection of damage(RAPID) technique.Secondly, a reference-free damage identification method based on signal correlation coefficient was studied. By arranging a rectangular array on the structure, several excitation and receiving paths of the same direction are formed. The signal correlation coefficient is calculated by using the extracted effective signal. Compared with the signal correlation coefficient of the paths of the same direction is 1 or closed to 1 to determine the healthy path. After getting a certain direction of the healthy signal. Subtract the healthy signal from the damaged signal and the scattering signal of the damage is obtained. Finally, use the ellipse localization method to locate the damage.Finally, this paper explored the representation method of the damage degree based on the signal correlation coefficient. A pair of sensors are symmetrically arranged on the excited side of the structure, and the A0 mode wave is excited by the reversed phase excitation. Two cases of the same crack sizes, different locations and the same location and sizes, different crack propagation directions were researched.