Piezoelectric Paint Based 2-D Sensor Array for Detecting Damage in Aluminum Plate

A damage detection method based on an innovative 2-D phased sensor array made of piezoelectric paint (piezopaint) is proposed in order to find interaction of guided Lamb waves with various damage types in a thin isotropic plate structure. The fundamental flexural (or transverse), A0 mode, of the guided Lamb waves is used for this study. To enhance the damage detection technique using the 2-D phased sensor array, Empirical Mode Decomposition (EMD) and Hilbert-Huang Transform (HHT) are applied. New damage detection algorithm including threshold setting and damage index (DI) calculation is developed and evaluated for detecting simulated damages, in the form of holes and a crack. In this study, a 2-D phased sensor array with spiral configuration is fabricated by piezopaint and applied for detecting simulated damages in a 2024-T3 aluminum plate. Array responses were generated using a directional filtering algorithm based on phased array signal processing for damage cases and agree with actual damage locations. The characteristic Damage Indices consistently increase as damage size grows. In addition, the HHT amplitude results provide additional information for damage location and size estimation.