Monitoring crack propagation in turbine blades caused by thermosonic inspection

Bolu, G. and Gachagan, A. and Pierce, G. and Harvey, G. and Choong, L. (2010) Monitoring crack propagation in turbine blades caused by thermosonic inspection. In: REVIEW OF PROGRESS IN QUANTITATIVE NONDESTRUCTIVE EVALUATION. American Institute of Physics, p. 1654. ISBN 978-0-7354-0748-0

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Abstract

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.