Colorimetric Casing Testing via CIELAB Delta-a Thresholds

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Current non-destructive testing methods for composite casings with reinforcing fibers in turbomachines are inefficient and costly, as they rely on heat-sensitive paints that have limited service life and provide indirect, non-precise measurements of internal structural integrity, leading to increased downtime and maintenance costs.

Innovation Solution

A method using colorimetry measurements in the CIELAB color space to determine overheating risks by comparing a tested area to a reference zone, calculating Δa, Δb, and ΔL values, and establishing thresholds to assess mechanical integrity without requiring physico-chemical analysis, allowing for on-site decision-making.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If heat-sensitive paints are applied to the crankcase for non-destructive testing, then temperature indication is improved, but the service life is limited and requires frequent repainting

Engineering Contradiction:
Improvetemperature indicationVSAvoidservice life of paint
Core Design Contradiction:
Measurement precisionVSDuration of action of stationary object

Solution Approach 1:

The patent replaces the mechanical/chemical heat-sensitive paint system with an optical detection system using a camera and image processing. The method captures thermal information through optical means and processes images to detect temperature variations, eliminating the need for physical paint application and extending the duration of the testing capability indefinitely.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an intermediary system consisting of a camera, image processing unit, and reference database that mediates between the crankcase and the analysis system. This intermediary captures and processes thermal information without requiring direct contact with heat-sensitive materials, providing a durable and reusable testing method.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Illumination intensity

If heat-sensitive paint is used for testing, then temperature visualization is improved, but the indirect measurement reduces precision of structural condition assessment

Engineering Contradiction:
Improvetemperature visualizationVSAvoidstructural condition assessment
Core Design Contradiction:
Illumination intensityVSMeasurement precision

Solution Approach 1:

The patent substitutes the indirect visual indication of heat-sensitive paint with direct optical detection using a camera system. The image processing unit directly analyzes thermal patterns and structural characteristics, providing both visualization and precise structural assessment in a single integrated system.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Ease of manufacture

If conventional cleaning by stripping is performed on the engine, then the crankcase is cleaned, but the heat-sensitive paint is completely removed requiring repainting

Engineering Contradiction:
Improvecleaning efficiencyVSAvoidpaint layer durability
Core Design Contradiction:
Ease of manufactureVSDuration of action of stationary object

Solution Approach 1:

The patent extracts the testing function from the paint layer itself. Instead of relying on the paint to provide the testing capability, the system uses external optical detection to capture thermal information. This separation allows the paint to serve only its protective and cosmetic functions while the testing capability is provided by the reusable camera and image processing system.

Inventive Principle:
Principle #2Taking out (Extraction)

4Measurement precision

If laboratory physicochemical analysis is performed to assess overheating, then precise structural condition is determined, but the part must be removed from the mechanical assembly increasing downtime

Engineering Contradiction:
Improvestructural condition determinationVSAvoidaircraft downtime
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces the mechanical removal and laboratory analysis process with an in-situ optical detection system. The camera and image processing unit can assess structural conditions directly on the mounted crankcase, eliminating the need for disassembly and laboratory testing while maintaining high measurement precision through advanced image analysis.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent performs preliminary assessment using the optical detection system on the mounted crankcase before any disassembly occurs. This preliminary action provides sufficient information to determine whether further laboratory analysis is needed, reducing the frequency of time-consuming removal operations.

Inventive Principle:
Principle #10Preliminary action

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 rapid, reliable assessment of overheating risks and mechanical integrity, reducing unnecessary maintenance and downtime by providing a precise, non-destructive testing method that can be performed on-site, thereby minimizing aircraft downtime and operational costs.

Implementation Method 1

perform at least one colorimetric measurement on the said area determined to be checked and obtain the value a p of parameter a of the CIELAB color space

Methodology Applied
Scientific EffectColorimetry:

Data Source

PatentEP3585982B1Method for non-destructive testing of a casing by colorimetry
Publication Date: 2021.04.21 SAFRAN AIRCRAFT ENGINES SAS
  • EP3585982B1 patent drawingFigure 1~2
  • EP3585982B1 patent drawingFigure 3~4
  • EP3585982B1 patent drawingFigure 5~6

AI summary

The invention relates to a method for non-destructive testing of the heating of a predetermined zone (24) to be tested of a part (10) made of polymer material, the method including the following steps: a) taking at least one colorimetry measurement on said predetermined zone (24) to be tested and obtaining the value ap of the parameter a of the colorimetric space CIELAB; b) taking at least one colorimetry measurement on a reference zone (26) of said part (10) and obtaining the value ap/ref of the parameter a of the colorimetric space CIELAB; c) calculating Δap = ap— ap/ref; and d) establishing a risk of heating of said predetermined zone (24) to be tested if Δap is higher than a threshold value A1.