Laser thermography NDT for the inspection of debonding in titanium based Fibre Metal Laminates

Abstract

Abstract Fibre Metal Laminates (FMLs) describe a number of aerospace-grade layered structural materials where thin metal alloy foils are interleaved with Fibre Reinforced Polymer (FRP) plies. The evaluation of bonding integrity in multilayered primary structures is of great importance, as is generally the case with the specific performance requirements of aeronautical applications. This work describes the successful implementation of an Infrared-NDT approach to evaluate debonds in FMLs panel made of Titanium/Graphite (Ti-Gr). The proposed approach uses a flying laser heat-source, raster scanning the surface, in search of defect signatures arising on the temperature distribution profile left by the moving laser, and acquired from the component surface by an IR camera. A numerical simulation of the above NDT approach is proposed and used to investigate the mechanisms allowing to correlate defects signatures to defect features and material thermal response. The outcomes of the model are also evaluated in order to optimize the experimental setup.