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 Contribution

Abstract

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.

Fingerprint

Turbomachine blades
Turbines
Turbofan engines
Vibration measurement
Nondestructive examination
Frequency response
Compressors
Computer aided design
Screening
Inspection
Cracks
Finite element method
Defects
Lasers
Costs
Defect detection

Keywords

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

Cite this

Bolu, Gabriel Nnamdi ; Pierce, Gareth ; Gachagan, Anthony ; Barden, Tim ; Harvey, Gerry. / Investigations into the vibrational response of an aero-engine turbine blade under thermosonic excitation. In: Key Engineering Materials. 2012 ; Vol. 518. pp. 184-192.
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abstract = "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.",
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Investigations into the vibrational response of an aero-engine turbine blade under thermosonic excitation. / Bolu, Gabriel Nnamdi; Pierce, Gareth; Gachagan, Anthony; Barden, Tim; Harvey, Gerry.

In: Key Engineering Materials, Vol. 518, 2012, p. 184-192.

Research output: Contribution to journalConference Contribution

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AU - Pierce, Gareth

AU - Gachagan, Anthony

AU - Barden, Tim

AU - Harvey, Gerry

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