离散解析互相关的Lamb波频散特性估计方法

A discrete analytic cross-correlation method for the estimation of the dispersion characteristic of Lamb waves is proposed to deal with the problem that conventional experimental estimation of the dispersion characteristics of Lamb waves is often realized by means of sensor array or intensive sampling in a space. A transducer serving as the receiver is placed at two adjacent positions to collect signals of Lamb wave response by using the pitch-catch technique. The group delay and phase delay of wave packets are estimated by calculating the discrete analytic cross-correlation between two response signals and between the original excitation signals and the response signals. On this basis, dispersion curves of both the group velocity and phase velocity of desired modes are simultaneously obtained. Numerical and experimental results show that when the signal-to-noise ratio is above 15 dB, the maximum relative error of A₀ mode and S₀ mode estimated by the discrete analytic cross-correlation method is about 1%. In the case that the prior knowledge of geometric parameters and material properties of the structure to be inspected is unknown, the method accurately estimates the Lamb wave dispersion characteristics with only two tests. It is the high efficiency of test and calculation that the discrete analytic cross-correlation method fully satisfies the engineering demand.