Flow-Induced Passive Random Guided Wave in a Thin-Plate and its Application on Dispersion Curve Estimation

Flow-induced random vibration propagates a long distance in a thin-plate structure, contains information of the structural properties and states, and thus can be used for the structural health monitoring. This paper shows via experimental data that the flow velocity is essential to excite a sufficiently high frequency of random guided wave. More specifically, spraying compressed air with flow velocity around 30 m/s onto the plate surface generates a broadband random guided wave of A0 mode up to 100 kHz. The group velocity for different frequencies, and thus the dispersion curve of the A0 mode, can be derived by the cross-correlation between two sensors along after performing a band-pass filter. In addition, the sensor distance and the signal length are also important for the group velocity estimation, a quantitative analysis of which is presented in this paper.