Investigations into the vibrational response of an aero-engine turbine blade under thermosonic excitation

Gabriel Nnamdi Bolu, Gareth Pierce, Anthony Gachagan, Tim Barden, Gerry Harvey

Research output: Contribution to journalConference Contributionpeer-review


Thermosonics is a rapid and potentially cost-saving non-destructive testing (NDT) screening technique that can be applied to the identification of cracks in high pressure compressor turbine blades in turbofan engines. The reliability of the thermosonic technique is not well established for inspecting these complex components; in particular the vibrational energy generated within a component during a thermosonic test is often highly non-uniform, leading to the possibility of missing critical defects. The aim of this study was to develop a methodology, using a combination of vibration measurements and finite element analysis (FEA), to model the vibrational energy within a turbine blade in a typical thermosonic inspection scenario. Using a laser vibrometer, the steady-state vibration response (i.e. frequency response) at several locations on a blade was measured and used to identify the prominent peaks in the frequency spectra. These were then used to generate an excitation function for the finite element modelling approach. Acceptable correlation between the measured and simulated vibration response at a number of specific locations on the blade allowed the forcing function to simulate the vibration response across the whole blade. Finally, the predicted displacement field was used to determine the vibrational energy at every point on the blade which was mapped onto a CAD representation of the blade, thereby highlighting areas on the blade that were below the defect detection threshold.
Original languageEnglish
Pages (from-to)184-192
Number of pages9
JournalKey Engineering Materials
Publication statusPublished - 2012
Event2nd International Workshop on Smart Diagnostics of Structures - Krakow, Poland
Duration: 14 Nov 201116 Nov 2011


  • thermosonics
  • nde
  • ndt
  • investigations
  • vibrational response
  • aero-engine turbine blade
  • thermosonic excitation


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