Time-domain Analyses and Correlations of Lamb Wave Signals for Damage Detection in a Composite Panel of Multiple Stiffeners

The propagation characteristics of Lamb waves activated and collected by an active piezoelectric sensor network in a carbon fibre (CF)/epoxy (EP) composite panel of five stiffeners were investigated. In particular, attenuation and dispersion of Lamb waves induced by reinforced stiffeners were evaluated, and angular dependence of propagating velocity of Lamb waves in the composite structure was studied. The interaction between Lamb wave modes and damage (a through-thickness hole) was subsequently examined. An inverse algorithm based on correlations between the digital damage fingerprints (DDFs) of wave signals in the benchmark and damaged structures was developed for damage identification. DDFs extracted from the captured wave signals were used to achieve efficient data compression for the calculation of correlation coefficients. Different combinations of actuator-sensor paths were used to estimate the location of damage. The results confirm that the proposed algorithm is able to identify damage in such a complex composite structure.