Some aspects of electromagnetic testing of composites

The high strength-to-weight ratio of composites make them attractive for the manufacture of items ranging from aerospace products such as helicopter rotor blades to sports equipment. Despite their advantages, composites still need to be monitored for quality and safety reasons during the fabrication process and in-service operations. Detection by NDT of flaws in composites remains difficult due to their heterogeneity, anisotropy and multi-layered structure. Each non-destructive testing technique has its own strength and limitations depending on the material tested and the type of flaw being sought. Among these, electromagnetic techniques for composite examination are a low-cost alternative to more conventional techniques such as ultrasound, and are reviewed in this paper.