Monitoring crack propagation in turbine blades caused by thermosonic inspection

High power acoustic excitation of components during a thermosonic (or Sonic IR) inspection may further propagate existing cracks. Monitoring such changes through destructive or non-destructive means is no trivial task. Process Compensated Resonance Testing (PCRT) technology offers the capability to monitor the growth of fatigue-induced cracks (and other progressive defects) through statistical analysis of changes in a components resonant spectra over time. This technique can be used to detect changes in material properties by comparing a components spectra to itself at regular intervals after systematic exposure to high power excitation associated with thermosonic inspection. In this work, the resonant spectra of 6 cracked and 6 uncracked turbine blades are captured prior to batch of inspections. Next, these spectra are analysed using proprietary software for changes in resonant behaviour. Results from this work indicate that a typical thermosonic inspection of a turbine blade for crack detection does not cause crack propagation or degrade a blades structural integrity.