Accession Number:

ADA128819

Title:

Demonstration of the Electric Current Perturbation Technique for Fatigue Crack Characterization in TF-33 Turbine Disk Tiebolt Holes.

Descriptive Note:

Final rept.,

Corporate Author:

SOUTHWEST RESEARCH INST SAN ANTONIO TX

Report Date:

1979-11-01

Pagination or Media Count:

54.0

Abstract:

The Electric Current Perturbation ECP technique was evaluated to demonstrate its capability to detect and characterize low-cycle fatigue cracks in tiebolt holes of TF-33, third-stage turbine disks. Examinations were performed on one hundred tiebolt holes in ten scrap disks. Signatures were correlated with twelve cracks which were metallurgically examined and sectioned to determine crack size, shape and orientation. Correlation of ECP signatures with the metallurgical results confirmed detection in one case of a very small and relatively isolated crack of approximately 0.30 mm 12 mils surface length by 0.14 mm 5.4 mils deep. Smaller cracks were also detected however, their signals were complicated by influences from adjacent cracks. Calculations indicate that the ECP method is capable of detecting cracks approximately 0.25 mm 10 mils long by 0.08 mm 3 mils deep at a signal-to-background ratio of approximately two with the present probe design. An overall appraisal indicates that the ECP method offers high sensitivity even to very small fatigue cracks the potential to discriminate between single and multiple cracks and the potential to obtain crack characterization parameters. Author

Subject Categories:

  • Test Facilities, Equipment and Methods
  • Electricity and Magnetism
  • Mechanics
  • Jet and Gas Turbine Engines

Distribution Statement:

APPROVED FOR PUBLIC RELEASE