SBIR-STTR Award

Reliable diagnosis of stress corrosion cracking (SCC) in aircraft components at an early stage is critical for maintaining mission readiness and safety. One of the primary challenges associated with maintenance management for aircraft components is that SCC does not grow at a steady rate over the life of the component, but rather the majority of the remaining useful life is spent before macroscale SCC initiates. Many traditional inspection technologies failed to effectively detect microscopic SCC in aircraft components. FBS proposes a novel nonlinear ultrasonic guided wave inspection approach and device for detecting microscopic SCC at an extremely early stage along with guided wave imaging capability of accurately identifying and characterizing macroscale SCC. Nonlinear guided waves are sensitive to microstructure change of the material and can be utilized to evaluate material properties even before the initiation of macroscale SCC. Linear guided wave scan can be used to generate damage imaging of SCC at a later stage. Another benefit of guided wave inspection is that it is able to perform long-distance inspection of hidden or inaccessible regions of the aircraft, and the sensors can be completely contained within the airframe.

Sudden structural failure caused by stress corrosion cracking (SCC) in aircraft components is becoming a severe safety threat to Air Force aircraft and other aviation vehicles. Detection of SCC often occurs late in the damage development cycle, in which fast-growing macroscale cracking has already developed. This significantly increases depot maintenance cost and can negatively impact aircraft availability and integrity. Therefore, early detection of SCC in an aircraft component is a key element of fleet maintenance operations that has a tremendous impact on mission readiness, safety, and life cycle cost. Earlier planning of maintenance operations will allow for more effective logistics and maximization of mission readiness. Guidedwave proposes a nonlinear ultrasonic guided wave technology for detection of SCC. A hand-held probe will be used for small and wide area identification of early-stage SCC on both flat and curved surfaces of aircraft components. The probe will detect early-stage SCC so that it can be repaired prior to macrocrack formation. The probe will then verify that the repaired area is free from SCC damage. Phase II will focus on development of a prototype portable SCC detection system for demonstration on multiple Air Force platforms.