Polyurethane Filling Element for Aircraft Composite Preforms
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Solution Overview
Problem
Aircraft parts manufacturing faces challenges in preventing premature failure of filling elements and interfaces under high deployment loads, particularly due to mechanical incompatibility and lack of consideration in stress analysis, leading to potential mechanical failure.
Innovation Solution
A filling element made of polyurethane or silicone, optionally with bonding strips, is used between preforms, providing a flexible and compatible interface that supports shape maintenance and prevents contamination, made by extrusion, injection molding, or lamination, and is compatible with epoxy resins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional epoxy resin filling elements are used, then they provide structural support, but they are prone to premature failure under high deployment loads due to mechanical incompatibility
Solution Approach 1:
The patent changes the material parameters of the filling element from traditional epoxy resin to polyurethane or silicone materials. These materials exhibit superior flexibility and elastic properties, allowing them to withstand high deployment loads without premature failure. The material parameter change directly addresses the mechanical incompatibility issue by selecting materials with appropriate stress-strain characteristics for the application.
Solution Approach 2:
The invention uses polyurethane or silicone as composite filling materials that combine flexibility with structural integrity. These materials can be formulated with specific properties to match the mechanical characteristics of adjacent preforms, creating a composite system that prevents failure at the interface while maintaining overall structural strength under deployment conditions.
2Shape
If rigid filling materials are used to maintain shape during manufacturing, then shape support is provided, but mechanical failure occurs under operational loads
Solution Approach 1:
The patent employs dynamic materials (polyurethane or silicone) that can adapt their mechanical properties based on operational conditions. During manufacturing, these materials maintain shape through their viscoelastic properties. During operational deployment, they dynamically respond to loads by deforming elastically rather than failing rigidly, thus preventing mechanical failure while maintaining shape integrity.
Solution Approach 2:
The invention uses flexible polyurethane or silicone filling elements that can deform under load without failing. These flexible materials provide shape support during manufacturing through their structural integrity, then accommodate deployment loads through elastic deformation, preventing the rigid-failure mode that occurs with traditional materials.
3Strength
If filling elements are made to be flexible, then mechanical performance improves, but they may not provide adequate support during manufacturing
Solution Approach 1:
The patent selects polyurethane or silicone materials with specific mechanical parameters that balance flexibility and structural support. These materials have appropriate modulus values and tensile strengths that enable them to provide shape support during manufacturing while maintaining the flexibility needed to withstand deployment loads without failure.
Data Source
Figure 1~2
AI summary
The filling element for the manufacture of aircraft parts comprises a filling body (1) made of polyurethane or silicone, and may also comprise joining tapes (4), e.g., made of polyurethane. It allows to improve the mechanical performance of the aircraft part manufactured with such a filling element, as its material is more flexible than traditional epoxy resins, to fill the gap between preforms with a material that prevents any contamination during the manufacturing of the part or its operational life, to avoid mechanical failures, as it is bakeable and compatible with epoxy resins, and to provide support and maintain the shape during the manufacturing of the part, for example against the pressure required to evacuate volatiles in composite elements.