Digital Sequence and Virtual Path Construction-Based Impact Imaging Method for Onboard Monitoring of Aerospace Composite Structures

Abstract

Because of the rapidly growing use and poor impact resistance of composite materials, impact monitoring of composite structures has become more and more important, especially for aerospace engineering applications. Among the existing impact monitoring methods, piezoelectric transducer (PZT) network and guided wave-based imaging method has proved to be an effective structural health monitoring (SHM) technology. However, the pursuit of accurate localization of ordinary impact imaging methods comes at a cost, the high requirement for the SHM hardware system making these methods inapplicable for onboard impact monitoring. In order to realize accurate impact monitoring of aerospace composite structures onboard, this paper proposes a digital sequence and virtual path construction-based impact imaging method, which is simple enough to work in a digital impact monitor with a greatly simplified hardware system. The monitor is used to convert the impact response signals of PZTs into digital sequences, based on which the method first recognizes the impact occurring sub-region. Then, the virtual pitch–catch paths of the recognized sub-region are innovatively defined and constructed to estimate the impact-induced influence on these paths so that the path-synthesis imaging algorithm-based impact imaging can be performed with little computation cost. To verify the feasibility and effectiveness of the proposed method, a total of 90 impacts are applied on a composite unmanned aerial vehicle (UAV) wing, and experimental results show the good performance of accurate impact imaging and localization.