Application of Wave Propagation and Vibration‐based Structural Health Monitoring Techniques to Friction Stir Welded Plate and Sandwich Honeycomb Panel

Wave propagation and vibration‐based structural health monitoring methodologies are presented to detect, locate and quantify dent/crack, thermal debond, and corrosion damage in a solid aluminum friction stir weld plate and a sandwich honeycomb thermal protection panel. A wave propagation based method can identify small defects because propagating waves typically consist of small wavelengths while a vibration‐based scheme is better equipped to quantify damage over wide areas of large structures. Near‐real time online diagnostics is achieved by using localized sensing (wave propagation) and distributed sensing (vibration‐based) in an active measurement array. Sensor/actuator arrays have been developed to implement these techniques and portable health management systems have been developed based on the combination of damage detection algorithms, active sensing, and graphical user interfaces. Propagating waves are shown to have a heightened sensitivity to damage located at the anti‐nodes of a friction stir we...