Lamb wave based multistage damage detection method

Abstract

A multi-stage damage detection method based on Lamb waves is proposed for plate-like structures, which is not only for locating the damage position accurately, but also for estimating the damage size precisely. Considering a layout of PZT wafers in a square grid arrangement, the multi-stage damage detection method is based on the same PZT layout to achieve the damage detection in multiple stages with improving accuracy. Firstly, an aluminum plate with a hole is identified numerically by finite element method based on the multi-stage method. After the group velocity of Lamb wave in an aluminum plate is obtained numerically by the time of flight (ToF) and cross-correlation method, the position and size of holed-damage can be assessed by the first stage detection. The second stage is carried through one more data obtained by the same layout of PZT wafers, and the size of hole can be estimated more precisely. The third stage only depends on the need of improving detection results of the second stage. An experimental verification is carried through the multi-stage detection method applied in an aluminum plate with a hole. Therefore, the proposed method based on PZT wafers can conduct a multi-stage damage detection in the same PZT layout, and it can reach to a more accurate assessment quantitatively without requiring more PZT wafers. The method is simple and straightforward, and very cost effective in damage detection of plate-like structures.