Optical Sensor for Detection of Fatigue Damage Precursors

Investigation into fatigue damage precursors over the last decade has demonstrated that surface-evident defects such as cracks and slipbands evolve in a regular manner, which corresponds to the development of fatigue damage. Through examination of the evolution of such damage precursors in a component, this regularity can facilitate prediction of the component?s remaining fatigue life. The proposed Phase 2 work is to develop and characterize a sensor for in-situ examination and historical tracking of the precursor defects and to construct the analytical framework for using that data to predict the onset of catastrophic failure. Since a major application of this technology is for monitoring fatigue damage in aircraft components, the proposed system will be compact, durable, and relatively inexpensive. The Phase I results have confirmed models of precursor evolution on surfaces; and testing of several prototype surface inspection devices has shown that the technology is compatible with the restrictions on light sources, beam scanners, detection systems, and communication interfaces which this application demands. Design analysis and preliminary designs have also been completed for the in-situ sensor modules as well as their supporting communications and control systems, so that this technology is now ready to enter Phase II development.