Engine Titanium Consortium - Center for Nondestructive Evaluation ...

A report documenting the relative effectiveness of conventional and Multizone systems for the
ultrasonic inspection of billet.
Revised estimates of POD for larger diameter titanium billet (10″ to 14″).
POD and PFA estimates for nickel billet, including comparison with POD results from existent
methodologies.
Estimates of POD and PFA for titanium billet based on use of the random defect block, CBS data,
and data reported to JETQC, including comparison with POD results from existent methodologies.
Metrics:
A procedure for incorporating the properties of naturally-occurring defects into a model-based POD
methodology will have been defined in a formal report which becomes the basis for industrial
practice, providing a consistent basis for future implementation of the POD methodology.
The success of the new POD methodology developed in Phase I will be critically reviewed in terms
of attainment of the original goals, using the following criteria:
• POD results are more accurate than those of existing methodologies. They should be close
(e.g., flaw size for a given probability within ±40%) to those from existing (R e and â-versus-a)
methods when the requirements of those methods are satisfied and provide sensible
predictions in cases in which the existing methods cannot produce answers.
• PFA results are estimated as a function of threshold and these estimates are validated by
independent experiments.
• The method provides a means to predict the effect on POD and PFA of changing (as a
minimum) transducer beam properties (diameter, focal length, water path, beam orientation);
transducer frequency; scan index; flaw properties (location, dimensions, acoustic impedance,
orientation relative to the sound beam); material properties (acoustic impedance,
grain-boundary noise), with experimental validation that the response agrees with that predicted
by the model, as a result of changing any one of these parameters, within accuracies typical of
ultrasonic measurement, i.e., about ±3 dB (or ±40%).
Modifications will be developed that will enhance the speed, simplicity of use, and range of
applicability of the POD software developed in Phase I; the ease of operation will be demonstrated
by successful transfer of the software to one or more OEMs.
Estimates of the POD of hard-alpha defects in titanium billets will be extended to cover billet
diameters up to 14″. Success of this enhanced capability for assessing the quality of one of the
materials used in manufacture of aircraft engines will be indicated by incorporation of these
estimates in life management calculations by the FAA, members of ETC and the Rotor Integrity
Subcommittee of AIA.
Estimates of the POD of hard-alpha defects in titanium billets, and of white spots in nickel billets,
will be updated periodically. Success will be indicated by incorporation of these estimates in life
management calculations by the FAA, members of ETC, and the Rotor Integrity Subcommittee of
AIA.
Quarterly Report – January 1, 2002 –March 31, 2002
print date/time: 6/6/2002 - 8:39 AM – Page 96