Correlative sensor array and its applications to identification of damage in plate-like structures

Lamb waves, the guided elastic waves in thin plate/shell structures, have been the core of intensive research for developing cost-effective damage identification techniques over decades. In this regard, appropriate and optimal allocation of actuators and sensors in a sensor array/network is a pivotal concern for achieving sufficient information to describe the damage and meanwhile for minimising interferences of multiple wave modes and complex wave reflection from structural boundaries. An active sensor array comprising a number of miniaturised piezoelectric wafers aligned strategically was developed in the study, named correlative sensor array (CSA) to reflect its mechanism based on signal correlation processing. Using the time differences of different Lamb waves captured by individual array members, a CSA is able to facilitate awareness of structural damage and subsequently to locate it. To ascertain time difference accurately, a signal processing algorithm capitalising on signal correlation and moving-window-based likelihood searching was integrated with the array. The CSA with integrated signal processing algorithm was then numerically and experimentally applied to the identification of a through-thickness hole in an aluminium plate, and the identification results have shown the feasibility and effectiveness of the CSA for pinpointing damage in plate-like structures. As supplement, limitations of CSA-based damage detection in terms of the effective detection area and sensitivity were explored.