Optical detection and discrimination of fatigue and damage in engineering materials

Optical detection of material damage, especially fatigue, has obvious importance in many aspects of engineering. Recent work in the area has shown that scanning light scattering is capable of detecting signs of fatigue and foreign-object damage on many types of surfaces; however, the persistent problem with practical implementation of this technique is the presence of background noise signals, false defect counts. Several new approaches to discriminating fatigue damage signals from non-fatigue-related signals have been developed, including filtering of 2-dimensional scattered intensity maps, peak detection and correlation among multiple channels, and exploitation of surface reflectance and scattering properties to control the information received by the sensor. Similar techniques are also shown to enable highly robust detection of foreign object damage (FOD) on turbine blade edges