基于Chirp激励信号频散补偿的高分辨率兰姆波检测

he dispersion of ultrasonic guided waves causes the energy of a signal to spread out in space and time as it propagates. This decreases the performance for damage detection significantly. There are a lot of signal processing methods proposed on how to obtain each mode under serious dispersion for this reason. In this paper, with the application of the well-established chirp technique, a new scheme is established to alleviate the dispersion effects by performing dispersion compensation on the desired narrowband excitation signals, and thus the time duration of received wave packet can be compressed during the extracting process. Furthermore, under broadband chirp excitation, multiple narrowband responses can be extracted from a single chirp response, which makes the optimal design of the excitation waveform much more efficiently. Numerical simulation and experiment are then carried on aluminum specimens to investigate the behavior of the proposed method and the strategy for parameters selection. By using this method, the structural features distributed closely can be recognized with ease in time domain.