Flat Thermocouple Ribbon for Composite Autoclave Curing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional thermocouple cables leave indentations and compromise vacuum seal integrity during the curing process of composite aerospace parts in autoclaves, due to their thickness and shape, which is unacceptable for both cosmetic and structural reasons.
Innovation Solution
A flat thermocouple ribbon with ultra-thin conductors (0.012″ or less in thickness) and insulation layers of fluorinated ethylene propylene (FEP) and polyimide film, which spreads compression force and prevents air leakage, is fabricated by laminating flattened thermocouple wires between thin polyimide layers and bonding with a low melting point polymer like FEP.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional thermocouple cables are used, then temperature monitoring is achieved, but indentations and vacuum seal failures occur
Solution Approach 1:
The patent applies this principle by using a thin film gasket material that can conform to the flat profile of the thermocouple ribbon, creating an effective vacuum seal without requiring thick cables. The thin film nature of the gasket allows it to seal around the slender ribbon structure while maintaining vacuum integrity.
Solution Approach 2:
The patent transitions from conventional round thermocouple cables to a flat ribbon geometry, changing the dimensional characteristics of the thermocouple assembly. This flat profile reduces the vertical thickness that would otherwise create indentations on the composite part surface during autoclave curing.
2Object-affected harmful factors
If flat thermocouple ribbon is used, then indentations are eliminated, but vacuum seal leakage may occur
Solution Approach 1:
A thin film gasket is used to seal around the flat thermocouple ribbon, conforming to its profile and preventing vacuum leakage while maintaining the low-profile advantage of the ribbon structure.
Solution Approach 2:
The gasket material is positioned specifically at the interface between the thermocouple ribbon and the vacuum bag, providing localized sealing quality where it is most needed to prevent leakage around the flat ribbon structure.
3Reliability
If thick thermocouple cables are used, then temperature monitoring is reliable, but cosmetic integrity of parts is compromised
Solution Approach 1:
The thermocouple assembly is changed from a round cable profile to a flat ribbon profile, reducing the thickness dimension that would create visible indentations on the composite part surface while maintaining functional performance.
Solution Approach 2:
The thin film gasket and flat ribbon structure work together to create a low-profile assembly that maintains temperature monitoring capability while minimizing visual impact on the cosmetic integrity of the cured composite part.
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
The solution eliminates indentations and ensures vacuum seal integrity, maintaining structural and cosmetic integrity of composite parts while allowing for effective temperature monitoring during the curing process.
Implementation Method 1
fabricated by laminating flattened thermocouple wires between thin polyimide layers and bonding with a low melting point polymer like FEP
Data Source
AI summary
A thermocouple ribbon features a pair of flat conductors and first and second layers of a polyimide film covering the conductors. The polyimide film preferably is coated with a fluoropolymer, such as fluorinated ethylene propylene (FEP). During manufacture of the thermocouple ribbon, the first and second layers of polyimide film, with the pair of flat conductors positioned there between, are heated above the melting temperature of the FEP. The completed thermocouple ribbon is then cooled. A thermocouple connector may then be attached to a first end of the thermocouple ribbon, while a welded thermocouple junction may be formed at a second end of the thermocouple ribbon.