In Situ Fastener-Integrated Crack Detection for Aircraft Fatigue Monitoring

KCF will develop a compact sensor which can detect fatigue cracks in aircraft structures around fastener through-holes without removing fasteners or significantly modifying the fastener or structure. The proposed sensor will induce a minor impact and analyze the local vibration modes and acoustic resonance of the structure to exploit changes in the free vibration of the fastener/structure combination when a fatigue crack is present. The principle of this inspection method has a long history as an NDT method, commonly referred to as a coin tap test, however the application of this method has remained relatively primitive and subjective. KCF will advance this tried and tested inspection method with modernized, high-sensitivity vibration and acoustic sensors coupled with a miniature piezo or solenoid impactor and our ultra-high bandwidth wireless data system. We will also investigate the feasibility of other NDT methods in novel packages by performing a survey of modern NDT modalities and assess their potential to solve the installed inspection requirements.