Guided Wave Beamsteering using MFC Phased Arrays for Structural Health Monitoring: Analysis and Experiment

Phased array beamsteering is an effective tool for damage detection and assessment method in a guided wave structural health monitoring system. Monolithic piezoceramic (PZT) actuators have been widely utilized for beamsteering by assuming omnidirectional point sources for each actuator. However, this assumption can lead to erroneous results for a phased array of actuators with anisotropic actuation, such as macro-fiber composites (MFC). The MFC actuators are investigated in this research for beamsteering considering the main lobe width, main lobe magnitude, and side lobe levels and compared to equivalently sized PZT actuators. Analytical models of the MFC and PZT actuators attached to an isotropic plate structure are presented and the genetic algorithm is used to determine the optimal timing sequences of the phased array elements for beamforming enhancement. The analysis results show that the MFC phased arrays have reduced the main lobe width and side lobe levels compared to the PZT phased arrays for a range of beamsteering angles. The area ratios of the MFC arrays are also found to be greater than the PZT arrays for these beamsteering angles. Experiments using the PZT and MFC phased arrays on an aluminum plate are performed and compared to the analysis results. The experiment results agree with the analysis results and demonstrate improved beamsteering of the MFC phased arrays for specific applications.