Non-destructive characterization of delaminated areas at interfaces between plies in carbon fiber/epoxy laminates with Foucault currents

Carbon fiber epoxy laminates are extensively used in the aerospace industry as they offer a combination of high performance with relatively low weight . However, damage may occur in these materials, either at the manufacturing level or during use, which may affect their structural integrity. Among th e type of damage which may occur, delamination is a common defect which cau ses a reduction in compressive strength and thus limits the life of laminat ed composites. If undetected, delamination may propagate during use due to mechanical loads and in the worst case may cause fracture of the material. Therefore, delamination in composite materials needs to be efficiently dete cted and accurately quantified for safety and economic reasons. Because cf their heterogeneity, multi-layered structure and anisotropy, the inspection of composite materials remains difficult with conventional NDT methods. A method making use of Foucault currents, and relying on the principle of ele ctromagnetic induction, can be adapted for the detection and characterizati on of damage in composite materials. The use of Foucault currents in charac terizing delaminated areas at interfaces between plies in carbon fiber/epox y laminates is addressed in this paper. It is demonstrated that Foucault cu rrents can accurately detect and quantify delamination in CFRP materials. F urthermore, the potential of this technique for monitoring defect propagati on in composite materials is discussed.