Detrended Resonance Spectra for Aircraft Structural Mode Detection

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Solution Overview

Problem

Existing non-destructive testing methods for aircraft propulsion system components are inadequate in accurately identifying structural modes and defects, such as cracks and voids, within the components.

Innovation Solution

A resonance inspection system utilizing a control assembly with a processing system that processes vibratory response signatures to generate multiple resonance spectra waveforms, detrends these waveforms, and identifies structural modes by detecting maximum slope points and peaks within specific frequency ranges, employing piezoelectric transducers to apply vibrations and measure responses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If existing non-destructive testing methods are used to inspect aircraft propulsion system components, then inspection can be performed on installed components, but the accuracy in identifying structural modes and defects (such as cracks and voids) is inadequate

Engineering Contradiction:
Improvedefect identification accuracyVSAvoidstructural mode identification reliability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent segments the complex vibratory response signature into multiple distinct resonance spectra waveforms (magnitude spectra, phase spectra, real spectra, imaginary spectra). Each waveform type provides different characteristics of the structural response, allowing for more precise defect identification by analyzing multiple segmented representations rather than a single composite signal.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from analyzing a single-dimensional vibratory response to examining multi-dimensional resonance spectra by generating and analyzing at least two different types of spectra waveforms (magnitude and phase, or real and imaginary components). This dimensional expansion enables more comprehensive defect detection by capturing different aspects of the structural response simultaneously.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Productivity

If resonance-based inspection is performed on installed aircraft propulsion system components, then minimal downtime and cost are required, but accurate identification of structural modes and defects is challenging

Engineering Contradiction:
Improveinspection efficiencyVSAvoiddefect detection accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent applies detrending processing to the resonance spectra waveforms before analyzing them for defects. This preliminary action removes unwanted trends and baseline variations from the spectra, preparing the data for more accurate defect identification. By performing this preprocessing step, the system maintains inspection efficiency while significantly improving the precision of structural mode and defect detection.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent introduces detrending as an intermediary processing step between data acquisition and defect analysis. This intermediary process mediates between the raw resonance spectra and the final defect identification, removing confounding factors and enhancing the clarity of the structural response signals, thereby improving measurement precision without adding significant time to the inspection process.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Measurement precision

If multiple resonance spectra waveforms are generated and analyzed with detrending, then structural modes can be accurately identified by detecting maximum slope points and peaks, but the processing complexity increases

Engineering Contradiction:
Improvestructural mode identification accuracyVSAvoidsignal processing complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent employs a unified processing approach that handles multiple types of resonance spectra waveforms (magnitude, phase, real, imaginary) through the same detrending and analysis methodology. This universal processing framework reduces the overall system complexity by applying consistent algorithms across different waveform types rather than requiring separate specialized processing paths for each waveform.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The detrending process serves multiple functions simultaneously: it removes baseline drift, enhances peak visibility, and prepares the data for automated maximum slope point detection. This self-service approach allows a single processing step to accomplish multiple objectives, reducing the need for additional separate processing operations and thereby managing complexity while maintaining high measurement precision.

Inventive Principle:
Principle #25Self-service

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables accurate identification of structural modes and defects in aircraft propulsion system components with minimal downtime and cost, facilitating efficient inspection of installed components.

Implementation Method 1

The probe includes at least one piezoelectric transducer electrically connected with the control assembly. The instructions, when executed by the processor, may further cause the processor to control the at least one piezoelectric transducer to apply a vibration to the component

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

The probe includes at least one piezoelectric transducer electrically connected with the control assembly. The instructions, when executed by the processor, may further cause the processor to control the at least one piezoelectric transducer to apply a vibration to the component and measure the vibratory response signature of the component

Methodology Applied
Scientific EffectPiezoelectric effect: Converse Piezoelectric Effect

Implementation Method 3

process resonance data including a vibratory response signature of a component over a portion of a frequency range of the vibratory response signature to generate a plurality of different resonance spectra waveforms

Methodology Applied
Scientific EffectResonance: Resonance

Data Source

PatentEP4647757A1Resonance inspection system and method for using same
Publication Date: 2025.11.12 RTX CORP
  • EP4647757A1 patent drawingFigure 1
  • EP4647757A1 patent drawingFigure 2
  • EP4647757A1 patent drawingFigure 3

AI summary

A resonance inspection system (94) configured to process resonance data including a vibratory response signature of a component (66) over a portion of a frequency range of the vibratory response signature to generate a plurality of different resonance spectra waveforms of the vibratory response signature. The plurality of different resonance spectra waveforms includes a first resonance spectra waveform (1030) and a second resonance spectra waveform (1032). The processing system is further configured to detrend the first resonance spectra waveform (1030) and the second resonance spectra waveform (1032) and identify a presence or an absence of a structural mode of the component (66) using the first resonance spectra waveform (1030) and the second resonance spectra waveform (1032). The presence of the structural mode is identified by determining the first resonance spectra waveform (1030) includes a maximum slope point (1038) at a first frequency of the portion of the frequency range and the second resonance spectra waveform includes a second peak at a second frequency of the portion of the frequency range.