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Publications & Standards

Read Vibrant’s publications, white papers and ASTM Standards to keep you up-to-date on the latest with PCRT.

Validation of Model-Trained Process Compensated Resonance Testing Inspection for Creep Deformation – A Model – Assisted Probability of Detection Study

A model-assisted probability of detection (MAPOD) validation of Process Compensated Resonance Testing (PCRT) inspection for creep deformation is presented. The PCRT inspection was trained entirely with resonance data from PCRT forward models that predicted the effect of creep deformation on resonance frequencies. The MAPOD validation was conducted with a combination of physical validation specimens and modeled specimens. The modeled specimens included simulations of the effects of uncertainty inherent in the measurement of physical samples. The results validated PCRT forward modeling accuracy for creep deformation, and accurate PCRT classification of acceptable and unacceptable levels of creep.

Fan Blade White Paper

This paper describes ways to apply Vibrant Process Compensated Resonance Testing (PCRT) to Fan Blades to improve Quality and to Reduce Risk.

SX White Paper

This paper describes ways to apply Vibrant Process Compensated Resonance Testing (PCRT) to single crystal parts to verify grain orientation.

Detection of Microtexture Regions in Titanium Turbine Engine Disks using Process Compensated Resonance Testing: A Modeling Study

Titanium alloys used by the aerospace industry, like Ti-64 or Ti-6242, with Microtexture Regions (MTR’s) have been shown to exhibit significantly reduced dwell fatigue lifetimes. Over the last several decades, these titanium alloys have been used for critical components such as turbine engine disks, which are then susceptible to failure well below their expected service life. Current Nondestructive Inspection (NDE) methods are time consuming and can miss MTR’s. Process Compensated Resonance Testing (PCRT) is a fast and accurate full-body NDE method that has been proposed for the detection of MTR’s in titanium turbine engine disks. PCRT excites a part’s resonance frequencies and correlates the resonance spectrum to the part’s material and/or damage state. Turbine engine disks with MTR’s will have different resonance spectra than fully isotropic disks. Both the MTR’s geometric parameters (i.e. size, location, and orientation) and the microstructural parameters (i.e. degree of [...]

Uncertainty Quantification of Resonant Ultrasound Spectroscopy for Material Property and Single Crystal Orientation Estimation on a Complex Part

A case study is presented evaluating uncertainty in Resonance Ultrasound Spectroscopy (RUS) inversion for a single crystal (SX) Ni-based superalloy Mar-M247 cylindrical dog-bone specimens. A number of surrogate models were developed with FEM model solutions, using different sampling schemes (regular grid, Monte Carlo sampling, Latin Hyper-cube sampling) and model approaches, N-dimensional cubic spline interpolation and Kriging. Repeated studies were used to quantify the well-posedness of the inversion problem, and the uncertainty was assessed in material property and crystallographic orientation estimates given typical geometric dimension variability in aerospace components. Surrogate model quality was found to be an important factor in inversion results when the model more closely represents the test data. One important discovery was when the model matches well with test data, a Kriging surrogate model using un-sorted Latin Hypercube sampled data performed as well as the best [...]

Process Compensated Resonance Testing Models for Quantification of Creep Damage in Single Crystal Nickel-Based Superalloys

Process compensated resonant testing (PCRT) is a full body nondestructive evaluation (NDE) method that measures the resonance frequencies of a part and correlates them to the part’s material state, structural integrity, or damage state. This paper describes the quantification of creep damage in a virtual part population via the correlation of PCRT parameters to creep strain using inversion methods and vibrational pattern recognition (VIPR) analysis. Modeled populations were created using the finite element method (FEM) for single crystal (SX) nickel-based superalloy dogbone and turbine engine airfoil geometries. The modeled populations include nominal variation in crystallographic orientation, geometric dimensions, and material properties. Modeled populations also include parts with variable levels of creep strain, allowing for NDE sensitivity studies. FEM model inversion tools quantified creep strain and distinguished it from other variations in the part populations. Resonant [...]

Detection and Quantification of Creep Strain Using Process Compensated Resonance Testing (PCRT) Sorting Modules Trained with Modeled Resonance Spectra

Process Compensated Resonant Testing (PCRT) is a full-body nondestructive testing (NDT) method that measures the resonance frequencies of a part and correlates them to the part’s material and/or damage state. PCRT testing is used in the automotive, aerospace, and power generation industries via automated PASS/FAIL inspections to distinguish parts with nominal process variation from those with the defect(s) of interest. Traditional PCRT tests are created through the statistical analysis of populations of “good” and “bad” parts. However, gathering a statistically significant number of parts can be costly and time-consuming, and the availability of defective parts may be limited. This work uses virtual databases of good and bad parts to create two targeted PCRT inspections for single crystal (SX) nickel-based superalloy turbine blades. Using finite element (FE) models, populations were modeled to include variations in geometric dimensions, material properties, crystallographic [...]

NDT Technology Readiness A P&WC Case Study

Presentation by Pratt & Whitney Canada to A4A NDT Forum describing a P&WC Case Study for application of PCRT. "P&WC was able to rapidly implement a PCRT inspection process that met the expectation of the various aviation regulatory bodies thus allowing the fleet to continue flying"

Resonance Ultrasound Spectroscopy Forward Modeling and Inverse Characterization of Nickel-based Superalloys

The objective of this paper is to investigate Resonance Ultrasound Spectroscopy (RUS) measurement models to more precisely connect changes in the resonance frequencies of nickel-based super-alloy material to the macro/microscopic state. RUS models using analytical solutions and the finite element method (FEM) were developed to address varying elastic properties, grain structures and creep. Experimental studies were performed investigating the effect of exposure to high temperatures and stress for varying part shape and three grain structure classes: single crystals, directionally-solidified and polycrystalline structures. Inversion using both traditional analytical models was enhanced in order to simultaneously estimate varying material properties and changes in part geometry due to creep. Inversion using surrogate models from FEM simulations was also developed, addressing varying crystal orientation and complex geometries. Results are presented comparing the forward model trends [...]

Modern NDT for Aging Aircraft

This technical paper covers the background of the PCRT technology and capabilities as it relates to specific applications for aerospace components. Highlighted are specific details for the application and validation of PCRT for in service testing of JT8D 1st stage high pressure turbine (HPT) blades to improve engine reliability. Experimental information pertaining to high temperature exposure and fatigue are also included. Additional information, related to defect detection in the CF6-80A 1st stage HPT blade and ceramic rolling elements used in hybrid bearings, is included as well.


  • U.S. Patent 10481104, 10718723 for Utilizing RI of in-service parts
  • U.S. Patent 9157788, 10067094 for Part evaluation system/method using both resonances and surface vibration data
  • U.S. Patent 8903675 for Acoustic system and method for NDT of a part through frequency sweeps
  • U.S. Patent 9228981 for Resonance Inspection-based surface defect system/method
  • U.S. Patent 9335300 for SAW mode-based surface defect method
  • U.S. Patent 9927403 for Resonance inspection sorting module array
  • U.S. Patent 10295510 for Part evaluation based upon system natural frequency
  • U.S. Patent 9074927 for Methods for non-destructively evaluating a joined component
  • U.S. Patent 9228980 for Non-destructive evaluation methods for aerospace components
  • U.S. Patent 10746704 for PCRT for process control

ASTM Standards

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