PCRT Applications and Capabilities8212;PCRT has been applied successfully to a wide range of NDT applications in the manufacture and maintenance of metallic and non-metallic parts. Examples of anomalies detected are discussed in 1.1. PCRT has been shown to provide cost effective and accurate NDT solutions in many industries including automotive, aerospace, and power generation. Examples of successful applications currently employed in commercial use include, but are not limited to:
(1) Silicon nitride bearing elements
(2) Investment cast steel rocker arms
(3) Cast gas turbine blades
(4) Stamped and brazed steel rocker arms
(5) Cast aluminum knuckles and control arms
(6) Cast ductile iron control arms
(7) Cast cylinder heads and cylinder blocks
(8) Sintered powder metal gears and clutch plates
(9) Machined forged steel steering racks
(10) Machined forged steel transmission gears and shafts
(11) Ceramic oxygen sensors
(12) Silicon wafers
(13) Gas turbine components
General Approach and Equipment Requirements for PCRT via Swept Sine Input:
PCRT systems are comprised of hardware and software capable of inducing vibrations, recording part response to the induced vibrations, and executing analysis of the data collected. Inputting a swept sine wave into the part has proven to be an effective means of introducing mechanical vibration, and can be achieved with a high quality signal generator coupled with an appropriate active transducer in physical contact with the part. Collection of the part’s frequency response can be achieved by recording the signal generated by an appropriate passive vibration transducer. The software required to analyze the available data may include a variety of suitable statistical analysis and pattern recognition tools. Measurement accuracy and repeatability are extremely important to the application of PCRT.
Hardware Requirements8212;A swept sine wave signal generator and response measurement system operating over the desired frequency range of the test part are required with accuracy better than 0.002 %. The signal generator should be calibrated to applicable industry standards. Transducers must be operable over same frequency range. Three transducers are typically used; one Drive transducer and two Receive transducers. Transducers typically operate in a dry environment, providing direct contact coupling to the part under examination. However, noncontacting response methods can operate suitably when parts are wet or oil-coated. Other than fixturing and transducer contact, no other contact with the part is allowed as these mechanical forces dampen certain vibrations. For optimal examination, parts should be placed precisely on the transducers (generally, ±0.062 in. (1.6 mm) in each axis provides acceptable results). The examination nest and cabling shall isolate the Drive from Receive signals and ground returns, so as to not produce (mechanical or electrical) cross talk between channels. Excessive external vibration or audible noise, or both, will compromise the measurements.
Constraints and Limitations:
PCRT cannot ..........
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