Fibrous Preform Impregnation via Deformable Membrane Pressure
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Solution Overview
Problem
Current methods for impregnating fibrous preforms, such as the 'poly-flex' and resin transfer molding (RTM) processes, face challenges in controlling the profile and definition of both sides of the part, leading to potential surface roughness and microporosity issues, which can affect the mechanical strength and completeness of impregnation.
Innovation Solution
A process using rigid supports and walls to shape and impregnate fibrous preforms with an impregnating composition, where a fluid is applied to maintain pressure and ensure complete infiltration, reducing the risk of incomplete impregnation and porosity, and allowing for the control of both sides' profiles during the densification process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the poly-flex process is used to impregnate fibrous preform, then the process is simple and can be implemented with a deformable membrane, but the surface definition and profile control on one side of the part deteriorates leading to rougher surface
Solution Approach 1:
The tool is segmented into two distinct parts: a rigid support for one face and a deformable membrane for the other face. This segmentation allows each part to perform its specific function - the rigid support provides precise surface definition while the deformable membrane allows for simple resin injection and adaptation to the preform shape.
Solution Approach 2:
Different qualities are applied to different parts of the tooling system. One face uses a rigid support with high dimensional stability for precise surface control, while the other face uses a deformable membrane for ease of operation. This local differentiation resolves the contradiction between simplicity and precision.
2Ease of operation
If resin is injected at distinct points in RTM process, then the injection process is controlled, but the impregnation completeness deteriorates as resin may not infiltrate entire preform
Solution Approach 1:
The invention transitions from point-based injection (zero-dimensional) to surface-based injection (two-dimensional). The deformable membrane allows resin to be injected across the entire surface area, ensuring complete infiltration of the preform while maintaining operational control.
Solution Approach 2:
The deformable membrane acts as an intermediary between the injection system and the preform. It distributes the resin uniformly across the preform surface while maintaining pressure control, ensuring complete impregnation without sacrificing injection control.
3Manufacturing precision
If autoclave cooking is used for consolidation of pre-impregnated laminates, then the densification is effective, but the manufacturing cost increases
Solution Approach 1:
The system uses the pressure from the deformable membrane itself to achieve densification during the curing process, eliminating the need for external autoclave equipment. The membrane maintains constant pressure on the preform throughout curing, providing effective densification at lower cost.
Solution Approach 2:
The invention replaces the complex mechanical autoclave system with a simpler deformable membrane system that uses fluid pressure to achieve the same densification effect. This substitution maintains densification quality while reducing manufacturing complexity and cost.
4Strength
If resin crosslinks in RTM process, then the structural strength is developed, but the shrinkage causes pressure loss and microporosity formation affecting mechanical strength
Solution Approach 1:
The deformable membrane is positioned and pre-loaded before resin injection and curing. This preliminary setup ensures that the membrane is ready to maintain constant pressure throughout the resin crosslinking process, preventing pressure loss and microporosity formation while the structural strength develops.
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 effectively controls the definition of both sides of the impregnated preform, reduces microporosity, and enhances the mechanical strength of the final composite material, while also allowing for the use of relatively viscous resins and potentially reducing manufacturing costs by avoiding autoclave curing.
Implementation Method 1
the application of the fluid on the wall on the side opposite the chamber does not modify the shape of the face of the wall located facing the rigid support and generates sufficient pressure on the wall to move it towards the support and reduce the internal volume of the chamber
Implementation Method 2
impregnating a fibrous preform with an impregnating composition
Data Source
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AI summary
A method for impregnation of a fibrous preform (10) by an impregnation composition (20), the method comprising the following step: • a) application of a liquid (30) onto a structure, the structure comprising: • - a chamber (2) in which a fibrous preform (10) to be impregnated is present, the chamber (2) being defined between a rigid support (3) on which the fibrous preform (10) is placed and a wall (4), the wall (4) comprising a face (4a) located facing the fibrous preform (10), and • - an impregnation composition (20), intended to impregnate the fibrous preform (10), the impregnation composition being present in the chamber (2), the liquid (30) being applied on the wall (4) of the opposite side of the chamber (2), the wall (4) being configured so that the face (4a) located facing the fibrous preform (10) retains its shape during application of the liquid (30), the applied liquid (30) enabling creation of a sufficient pressure to displace the wall (4) towards the rigid support (3) and impregnating the fibrous preform (10) with the impregnation composition (20).