Standard Practice for Part-to-Itself Examination Using Process Compensated Resonance Testing Via Swept Sine Input for Metallic and Non-Metallic Parts

Importancia y uso:

5.1 PCRT Applications and Capabilities—PCRT PTI examination has been applied successfully to a wide range of parts in manufacturing and maintenance environments. Examples of manufacturing processes, repair processes, and in-service damage mechanisms evaluated with PTI are discussed in 1.1. PCRT has been shown to provide cost effective and accurate PTI-based NDT, process monitoring, and life monitoring 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) Heat treatment operations:

(a) Aerospace gas turbine engine components (blades, vanes, disks).

(b) Additively manufactured components.

(c) Steel mechanical components.

(d) Industrial gas turbine blades.

(2) Induction hardening and carburization (both case-hardened and through-hardened parts):

(a) Gears.

(b) Ballnuts.

(3) Hot Isostatic Pressing (HIP):

(a) Gas turbine engine components (blades, vanes, disks).

(b) Additively manufactured components.

(4) Shot peening:

(a) Steel mechanical components.

(5) In-service thermal history, aging, creep damage, fatigue:

(a) Gas turbine engine components (blades, vanes, disks).

(b) Industrial gas turbine blades.

(c) Aircraft landing gear wheels.

(6) Maintenance repair/rejuvenation processes:

(a) Gas turbine engine components (blades, vanes, disks).

(b) Industrial gas turbine blades.

(c) Aircraft landing gear wheels.

5.2 General Approach and Equipment Requirements for PCRT via Swept Sine Input: 

5.2.1 PCRT systems comprise hardware and software capable of inducing vibrations, recording the component response to the induced vibrations, and analyzing 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 resonance response is achieved by recording the signal received 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.

5.2.2 Hardware Requirements—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.

5.3 Constraints and Limitations: 

5.3.1 PCRT cannot separate parts based on visually detectable anomalies that do not affect the structural integrity of the part. It may be necessary to provide additional visual inspection of parts to identify these indications.

5.3.2 Excessive variation in part geometry or base material properties may limit the sensitivity of PCRT PTI examination.

5.3.3 A direct measurement of a single geometric dimension of a region undergoing a material state change, such as the case depth (in centimeters or inches) of an induction hardened region, is generally not possible with PCRT PTI. The frequency changes are dependent on the total volumetric effect of the process that causes the material state change. With accurately trained acceptability limits, however, PCRT PTI is very effective at screening populations of components for acceptable and unacceptable processing.

5.3.4 PCRT will only work with stiff objects that provide resonances whose peak quality factor (Q) values are greater than 500. Non-rigid materials or very thin-walled parts will not yield useful Q values.

5.3.5 While PCRT can be applied to painted and coated parts in many cases, the presence of some surface coatings such as vibration absorbing materials and heavy oil layers may limit or preclude the application of PCRT.

5.3.6 While PCRT PTI examination can be applied to parts over a wide range of temperatures, it cannot be applied to parts that are rapidly changing temperature. The part temperature should be stabilized before collecting resonance data.

5.3.7 Misclassified parts in the teaching set, along with the presence of unknown anomalies in the teaching set, can significantly reduce the accuracy and sensitivity of PCRT.

Subcomité:

E07.06

Referida por:

F3704_F3704M-24, E0543-21, E3081-21, E2534-20, E0543-21

Volúmen:

03.04

Número ICS:

17.160 (Vibrations, shock and vibration measurements)

Palabras clave:

damage identification; elastic properties; feature extraction; manufacturing process; material state; nondestructive examination; nondestructive inspection; Part-to-Itself; Process Compensated Resonance Testing; process compensated resonant examination; process monitoring; production variation; quality control; repair process; resonance inspection; resonances; resonant frequency; resonant mode; Resonant Ultrasound Spectroscopy; system health monitoring; vibration characteristics ;