Eddy Current Modeling in Composite Materials

The production of carbon fiber reinforced polymers, which are widely used both in civil and military applications, is an elaborate process un-free from faults and problems. Problems during the manufacturing, such as plies' overlapping, can cause flaws in the resulting material, this way compromising its integrity. Compared with metallic materials, carbon epoxy composites show a number of advantages: Higher tensile strength, lower density and coefficient of thermal expansion, absence of fatigue state related phenomena, possible manufacturing of large layered structures. Within this framework, this work aims to propose a design of ferrite core probe for eddy current non destructive evaluation, in order to investigate the presence of defects in carbon fiber epoxy composite materials. The effect of the ferrite core is analyzed in order to focus magnetic flux density on the investigated specimen. Eddy currents generated by high speed ferrite core probe movement were investigated by using numerical simulation. Particularly, a Finite Element Approach has been exploited in order to characterize the transducer to specially emphasize the presence of defects in a multi-layer carbon fiber epoxy structure.