Infrared Spectroscopy for Polymer Casing Heating Detection
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Solution Overview
Problem
Current non-destructive testing methods for composite materials in turbine engine casings with reinforcement fibers are inadequate, as they either have limited service life, require costly thermosensitive paints, and provide indirect or imprecise measurements of internal structural integrity under heating conditions.
Innovation Solution
A method utilizing infrared spectroscopy to measure absorbance values and determine spatial frequency intervals, allowing for the calculation of heating temperature and exposure time by comparing data with a reference database, and standardizing measurements using a second peak independent of oxidation state to correct for non-specific absorption variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermosensitive paints are applied to the casing, then visual detection of heating is enabled, but the service life is limited and requires frequent repainting
Solution Approach 1:
The patent replaces the mechanical/chemical system of thermosensitive paints with an optical measurement system using infrared spectroscopy. This substitution eliminates the need for physical coatings that degrade over time, providing permanent detection capability without maintenance.
Solution Approach 2:
The patent creates a digital copy of the polymer's chemical state through infrared spectral analysis, allowing non-contact monitoring of heating effects without physically altering or degrading the casing surface, thus eliminating the service life limitation of physical paints.
2Reliability
If thermosensitive paints are used, then heating detection is possible, but the measurement is indirect and imprecise regarding internal structure
Solution Approach 1:
The patent uses infrared radiation as an intermediary that penetrates the polymer matrix to directly interact with the polymer chains and reinforcement fibers, providing direct measurement of internal structural changes rather than indirect surface indicators.
Solution Approach 2:
The patent measures changes in the polymer's chemical parameters (oxidation state, molecular structure) through infrared spectral shifts, enabling precise quantification of internal structural changes caused by heating rather than relying on indirect color changes.
3Ease of manufacture
If conventional cleaning by pickling is performed, then the casing is cleaned, but the thermosensitive paint is completely removed requiring reapplication
Solution Approach 1:
The patent replaces the chemical pickling process with non-contact infrared spectroscopic measurement, eliminating the need for aggressive chemical cleaning that removes protective coatings and requires reapplication.
4Ease of manufacture
If the casing is made from composite material with reinforcement fibres, then cost is reduced compared to metal, but mechanical integrity under heating is compromised
Solution Approach 1:
The patent implements continuous monitoring of the polymer's oxidation state through infrared spectroscopy, providing feedback on the actual thermal damage level to enable condition-based maintenance decisions that preserve mechanical integrity through timely intervention.
Solution Approach 2:
The patent monitors changes in the polymer's chemical parameters (oxidation state, molecular structure) through infrared spectral analysis to assess the actual mechanical integrity under heating conditions, allowing for condition-based maintenance decisions.
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
This method provides a simple, effective, and economical means to directly assess the polymer structure's state, ensuring the mechanical integrity of composite casings under heat, offering precise quantification and extended service life without the need for frequent repainting.
Implementation Method 1
carrying out a measurement by infrared spectroscopy at a region of said part to be tested and extracting therefrom the absorbance (or transmittance) values according to the spatial frequency
Implementation Method 2
from the absorbance values, determining an interval of spatial frequencies relating to the oxidation of the polymer of said region of the part
Data Source
AI summary
A method for the non-destructive testing of the heating of a part made from polymer material, the method comprising the following steps: a) carrying out a measurement by infrared spectroscopy on a part to be tested and extracting therefrom at least one of absorbance values and transmittance values according to a spatial frequency; and b) from the measurement of at least one of absorbance and transmittance, determining the period of time during which said region of the part to be tested has been subjected to a given heating temperature and determining said heating temperature, using a reference database comprising at least one of absorbance measurements and transmittance measurements, the measurements established over a plurality of reference samples made from polymer material that have been subjected to a given temperature during a given period of time.