Vibrant provides non-destructive testing (NDT) services for the most demanding aerospace and power generation applications. Vibrant’s proprietary inspection technology, Process Compensated Resonance Testing (PCRT), tests thousands of components for aircraft, aircraft engine, and power system OEMs and maintainers every year.
PCRT enhances safety of flight and operating economics by detecting process variation and structural defects that other methods cannot detect. It can replace destructive sampling, which may miss critical defects or needlessly scrap serviceable parts, with high-throughput NDT for 100% of the population. Vibrant’s PCRT services enable the customer to focus its internal NDT resources on characterization and analysis of defective parts to find and fix the causes of defects.
PCRT testing systems are configurable for a very broad variation of part geometries and materials. Systems are scalable for customer part volumes, with varying levels of automation from hand-loading to fully automated part handling.
Vibrant PCRT services include:
- Screening for Process Outliers
- Targeted Defect Detection
- Manufacturing Process Control (for existing and emerging processes)
- PCRT Life Monitoring
- Material Property Characterization
How does PCRT work?
PCRT is an NDT method based on the resonance frequencies of a part, which correlate directly to the part’s structural integrity. Material variations, geometric variations, and defects that affect structural integrity will affect the part resonance frequencies and be detectable with PCRT. PCRT features automated pattern recognition analysis of resonance spectra and statistical scoring of frequency data. The pattern recognition and scoring tools return an automated PASS/FAIL result that requires no operator interpretation. The frequency, scoring data and part/lot serialization are stored digitally for traceability and process monitoring and control. These data can also be used to monitor parts throughout their service life and detect the accumulation of fatigue.
Screening for Process Outliers
Outlier screening is the basic PCRT method for PASS/FAIL testing for production and in-service components. Resonance frequency data are recorded and automatically analyzed by Vibrant’s Vibrational Pattern Recognition (VIPR) algorithms and Mahalanobis-Taguchi System (MTS) statistical scoring. MTS scores parts on their similarity to the known good population and returns a PASS/FAIL result that requires no operator interpretation.
Targeted Defect Detection
For applications with specific defects of interest, a PCRT sort can be trained with examples of parts with those defects. VIPR will select resonance spectra patterns that identify both process outliers and parts with targeted defects. The statistical scoring algorithms will score parts on their similarity to both the good and known bad training populations and return automated PASS/FAIL results in production testing.
Manufacturing Process Control
PCRT data provide a unique way to characterize, monitor and control manufacturing processes. Resonance frequencies, and the MTS/Bias statistical scoring PCRT performs on those frequencies, can be used to establish process control limits, track process output vs. time and compare part populations to each other. PCRT process monitoring is used to characterize and qualify new manufacturing processes and add new control capability for existing processes. It can also be used to compare and qualify suppliers.
PCRT Life Monitoring
PCRT can track serialized parts throughout their service lifetime and detect the onset of fatigue failure.
PCRT spectra are extremely sensitive to changes within the same component. Spectra can be collected from a given part and compared each time it visits the shop. Part variation due to repair does not cloud part comparisons, because the part is always compared only to itself.
Resonance changes detected are due to changes in the part’s structural integrity, and can be used to evaluate the accumulation of fatigue, damage, or other life-limiting conditions. This offers opportunities for life extension for parts that are currently constrained by either a soft or hard hour limitation.
PCRT life monitoring can provide either a simple Pass/Fail result or a more in-depth review of the resonance data.
- For OEM’s, PCRT offers real world data on part performance over time
- For maintainers, PCRT offers a tool to predict the remaining life of individual components
- PCRT provides early warning of manufacturing or field performance issues
This example shows a PCRT part life monitoring study performed on aluminum 6061-T6 sample coupons. The screenshot shows spectra for the same part as it accumulated mechanical fatigue cycles. The spectrum shifts to the left as fatigue accumulates, with an accelerated shifting and pattern changes at the onset of cracking. Similar experiments have been performed for bolts, and while these are not as scientifically rigorous, the trends are similar, leading to high confidence that bolts that have accumulated significant fatigue, or stress from over-torque will be readily identified in a population of acceptable bolts.
Material Property Characterization
Vibrant’s RUSpec capability enables measurement of engineering material properties using a part’s resonance frequencies. These measurements provide an ideal tool for monitoring material processes or for material laboratory experiments.