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Application of an electromagnetic sensor for detection of impact damage in aircraft composites

This paper presents a comprehensive experimental study of barely visible impact damage detection for carbon-fibre reinforced polymer (CFRP) composites using an electromagnetic sensor: coupled spiral inductors. A multi-frequency inspection is performed, where the resultant images indicate its great potential for the evaluation of damage propagation. The accuracy and efficiency are compared with the open-ended waveguide imaging, near-field microwave microscopy and microwave time-domain reflectometry. Advantages, disadvantages and applications of these methods used for impact damage detection are described. It is found that the phase can also be used for evaluation other than the magnitude. The experimental results demonstrate that the sensor could offer an alternative method for the structural monitoring and maintenance of aircraft composite structures.