Three-Sheet Panel With Differential Thermal Expansion
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Solution Overview
Problem
Multilayer structures, such as three-sheet panels, face challenges with thermally induced stress due to thermal gradients, particularly in aerospace applications like thrust reversers, where temperature differences between face sheets cause stress that can lead to delamination and increased maintenance costs.
Innovation Solution
The solution involves creating a three-sheet panel with face sheets made of materials having different thermal expansion coefficients, specifically using INCOLOY Alloy 909 and INCONEL Alloy 625, where the core sheet is intercoupled between these face sheets, allowing for differential thermal expansion to manage stress and maintain structural integrity at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a three-sheet panel is used in a thrust reverser with thermal gradients, then the panel can withstand high temperature operation, but thermally induced stress causes delamination and structural degradation
Solution Approach 1:
The patent applies local quality by using different materials for the inner and outer face sheets, each selected for its specific thermal expansion properties. The inner face sheet is made of a material with lower thermal expansion coefficient to minimize expansion under heat, while the outer face sheet uses a material with higher thermal expansion coefficient to accommodate expansion, thereby reducing thermally induced stress and preventing delamination while maintaining structural integrity at high temperatures.
Solution Approach 2:
The patent employs composite materials by constructing the three-sheet panel with different alloy materials for each layer. The core sheet is made of INCONEL Alloy 625, the inner face sheet is made of INCOLOY Alloy 909, and the outer face sheet is made of INCONEL Alloy 625. This composite structure allows each layer to respond differently to thermal gradients, with the INCOLOY 909 inner sheet providing thermal stability and the INCONEL 625 sheets providing ductility and stress accommodation, thereby preventing delamination and maintaining reliability under high temperature operation.
2Ease of manufacture
If face sheets are made of the same material, then manufacturing is simplified, but thermal gradients cause stress and delamination
Solution Approach 1:
The patent applies local quality by using different materials for the inner and outer face sheets, each selected for its specific thermal expansion properties. The inner face sheet is made of a material with lower thermal expansion coefficient to minimize expansion under heat, while the outer face sheet uses a material with higher thermal expansion coefficient to accommodate expansion, thereby reducing thermally induced stress and preventing delamination while maintaining structural integrity at high temperatures.
Solution Approach 2:
The patent employs parameter changes by selecting materials with different thermal expansion coefficients for the face sheets. Specifically, the inner face sheet uses INCOLOY Alloy 909 with a lower thermal expansion coefficient, while the outer face sheet uses INCONEL Alloy 625 with a higher thermal expansion coefficient. This parameter change in material selection allows the panel to accommodate thermal gradients and prevent delamination, despite the increased manufacturing complexity.
3Ease of manufacture
If the core sheet is made of the same material as face sheets, then fabrication is easier, but thermal stress distribution is不均匀
Solution Approach 1:
The patent employs composite materials by constructing the three-sheet panel with different alloy materials for each layer. The core sheet is made of INCONEL Alloy 625, the inner face sheet is made of INCOLOY Alloy 909, and the outer face sheet is made of INCONEL Alloy 625. This composite structure allows each layer to respond differently to thermal gradients, with the INCOLOY 909 inner sheet providing thermal stability and the INCONEL 625 sheets providing ductility and stress accommodation, thereby preventing delamination and maintaining reliability under high temperature operation.
Solution Approach 2:
The patent applies local quality by using different materials for the inner and outer face sheets, each selected for its specific thermal expansion properties. The inner face sheet is made of a material with lower thermal expansion coefficient to minimize expansion under heat, while the outer face sheet uses a material with higher thermal expansion coefficient to accommodate expansion, thereby reducing thermally induced stress and preventing delamination while maintaining structural integrity at high temperatures.
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 approach reduces thermally induced stress, enabling the panel to withstand temperatures up to 1000°F without degradation, thus reducing maintenance needs and maintaining weight efficiency, as the differential expansion mitigates thermal gradients and prevents delamination.
Implementation Method 1
Each of the first and second face sheets is made of a material having a thermal expansion that is different from the thermal expansion of the other face sheet
Implementation Method 2
Superplastic forming is a metal forming process that takes advantage of the superplasticity of certain materials, such as titanium alloys, aluminum alloys and nickel alloys, at elevated temperatures
Data Source
AI summary
A panel comprises a first face sheet and a second face sheet spaced apart from the first face sheet. The panel further comprises a core sheet intercoupled between the first face sheet and the second face sheet. Each of the first and second face sheets is made of a material having a thermal expansion that is different from the thermal expansion of the other face sheet.