Analysis of damage localisation results in GFRP panel for different configurations of air-coupled transducers

In this paper results of the damage assessment of fiber-reinforced composite panels using guided wave propagation phenomenon are presented. For this purpose, non-contact elastic wave generation based on an air-coupled transducer (ACT) is utilised. Elastic wave sensing was based on a scanning laser Doppler vibrometer (SLDV). The problem of ACT slope angle for the effectiveness of elastic wave modes generation is analysed. It was shown that for an excitation frequency of 40 kHz it is possible to generate A₀ wave mode. The authors also investigated the damage sensitivity related to panel coverage area by elastic waves with large energy. An artificial damage in the form of Teflon inserts was utilised. Moreover, the influence of single and multiple acoustic wave sources on artificial damage localisation results was investigated. For this purpose RMS wave energy maps, statistical parameters, and damage indices are utilised. Different locations of ACTs and their influence on damage localisation results are investigated. A damage imaging algorithm based on wavefield irregularity mapping (WIM) has been proposed. In this research low-cost and popular, low-frequency ACT was utilised giving the possibility of realisation of the non-contact damage localisation method.