Impact monitoring in stiffened composite aerospace panels by wave propagation

Abstract

The technique of piezoelectric rosettes has been developed for the location of acoustic emission sources. Since the rosette-based acoustic emission source location algorithm is not dependent on the wave velocity, the method lends itself to monitoring complex composite structures where the velocity can change with wave propagation direction (due to anisotropy) or along the wave propagation path (due to tapered and multilayered geometries). This article presents the acoustic emission source location results from “blunt” impact tests conducted on a curved carbon fiber–reinforced plastic composite panel with co-cured stiffeners and bolted shear ties of overall dimensions of 0.9 m × 0.9 m. The results of these tests are of interest to follow the evolution of damage during the impact event. In addition, an impact force identification procedure is presented. The procedure is a model-based approach that minimizes the difference between predicted and experimental acoustic emission waves generated by the impact. The numerical procedure is tested favorably against the output of a hammer impact on a stiffened carbon fiber–reinforced plastic panel.