An Acoustic Travelling Wave System for High-Cycle Fatigue Analysis - Summary Report

Joshua Grant

Abstract


An acoustic travelling wave excitation system (TWS) has been developed by Defence
Science and Technology Group for the investigation of high-cycle fatigue issues related to
gas turbine engine bladed disks (blisks). To date, a simple research blisk has been tested
and used to validate the ability of the TWS to extract the modes and natural frequencies of
blisks. This study outlines the verification and validation of the TWS for use on a real, in-
service blisk. The natural frequencies and problematic ranges of harmonic excitation were
found with an error of 3% from FEM predictions. Furthermore, the system was found to be
robust towards any errors in the experimental set-up process, suggesting operation of the
acoustic TWS is much simpler than other methods of blisk excitation. Promising results
were also found for application of this system in evaluating the effect of mistuning and
blending repairs on the change in harmonic response. Finally, potential was identied for
use of the TWS in non-destructive investigation of material properties by the application
of FEM model calibration.

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