Engine Titanium Consortium - Center for Nondestructive Evaluation ...

ehavior of the transducers. This effort will begin as part of Task 1.1 and 1.2 which will concentrate
on fixed focus transducers. Two blocks (one for fixed-focus and one for phased array) suitable for
the evaluation of subsurface focused transducers will be manufactured to provide experimental
data with consideration given to samples available in 1.3.1. Based on this exercise, modifications
will be made to model input parameters or to the model code to improve the prediction accuracy.
Attention will also be paid to selection of transducer materials with consistent and measurable
properties, for example the machining of lenses from solid material rather than using cast-in-place
epoxy. Coordination with transducer and system vendors is expected with the objective of ensuring
that results of this effort impact the performance characteristics of future products used in jet engine
inspection.
Surface Finish Effects: The effect of surface finish on inspectability will be determined. Surface
finish requirements are anticipated to be more stringent at the higher sensitivity inspections
necessary for forgings (compared to billet) and will be a focus of study in this subtask. Empirical
and theoretical approaches will be used to assess the relationship between surface finish and
inspectability. Empirical studies will be limited to 100 machining passes spread across five 13”
diameter by 2” thick pancake samples. Results will be implemented in the UT modeling tools.
Transducer Design and Selection: The ultrasonic beam properties (frequency, depth-of-field,
diameter, bandwidth, mode, etc.) required to produce an acceptable 1/128” FBH calibration (FBH
@ 80%, Ti grain noise < 50%) will be defined. Fixed focus transducers for flat entry surfaces will be
designed, manufactured, and evaluated using appropriate ETC test specimens as necessary. An
assessment of the transducers (producing the above determined ultrasonic beam properties)
necessary to inspect the three OEM forgings will be made. Any additional required transducers will
be designed and manufactured. A commercial source for such transducers will be established.
Productivity Improvement: It was shown in Phase I that inspection sensitivity improvements will, in
general, increase the time required for the inspection. Fixed-focus transducer inspection
approaches have the advantage of being expandable (in an economical fashion) to include the
collection of data from multiple transducers simultaneously. This approach has the potential to
offset the productivity losses which will likely occur from the increased inspection sensitivity
required by this task. In order to meet the inspection time goals for this task, a study will be made
of the OEM forgings to determine potential areas of productivity improvement. A maximum
productivity approach will be defined and developed for evaluation in the laboratory demonstration.
Fixed Focus Laboratory Testbed: Laboratory testbed for the development and evaluation of the
fixed-focus inspection approach for a 1/128” FBH calibration forging inspection with digital C-scan
data acquisition and SNR based rejection criterion will be established. Additional transducers
necessary to inspect the OEM forgings will be designed, manufactured and tested. Scan plans for
the selected OEM forgings will be developed with model-based support. A limited number (1-2) of
each of the selected forgings will be inspected per the scan plan. Performance of the fixed focus
inspection approach for forging inspection will be documented. Alternative inspection technologies
will be identified using the experience base of the four partners, as well as NTIAC.
Phased Array Inspection: An evaluation will be made of available phased array technology to
determine which are potentially production-ready and capable. At this time, the digital focused
array transducer system DFATS annular phased array and the R/D Tech 2D array are known as
Quarterly Report – January 1, 2002 –March 31, 2002
print date/time: 6/6/2002 - 8:39 AM – Page 55