Composite Reinforcement Repair Using Contour Pressure Mat Curing
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Solution Overview
Problem
Current methods for reworking or replacing reinforcement elements in fibre composite structures, such as aircraft components made from carbon-fibre-reinforced plastics, require autoclaves and additional equipment, leading to increased costs, time, and potential for non-uniform pressure distribution and material deformation.
Innovation Solution
A method and device that uses a contour-adapted pressure mat supported by a fixing frame to apply pressure and heat directly to the reinforcement element, allowing for precise curing without an autoclave, using a pressure medium and integrated heating elements for uniform pressure and heat distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If an autoclave is used to apply pressure for curing fibre layers during reworking, then the curing pressure can be achieved, but the device complexity and cost increase, and additional space and time are required
Solution Approach 1:
The invention divides the pressure application system into modular components: a pressure mat divided into multiple pressure zones, a fixing frame with adjustable supports, and a heating device with separate heating zones. This segmentation allows the system to achieve autoclave-level pressure without requiring a full autoclave, reducing device complexity while maintaining curing effectiveness.
Solution Approach 2:
The pressure mat acts as an intermediary between the pressure source and the fibre layers, distributing pressure uniformly across the workpiece. The fixing frame serves as an intermediary structure that holds the pressure mat and applies mechanical support. These intermediary components enable pressure application without direct contact with the fibre composite structure, eliminating the need for a complex autoclave system.
2Device complexity
If mechanical clamping mechanisms are used to apply pressure, then pressure can be applied without an autoclave, but the pressure distribution becomes non-uniform causing pores and thickness fluctuations
Solution Approach 1:
The pressure mat is designed with differentiated local properties: different regions of the mat have different stiffness characteristics to match the local geometry and curing requirements of the fibre composite structure. The fixing frame includes adjustable supports that can be independently positioned to apply pressure uniformly across complex geometries. This local quality differentiation ensures uniform pressure distribution even on non-planar surfaces.
Solution Approach 2:
The pressure mat is designed with a flexible, conformable structure that can adapt to curved and complex surfaces. The mat's flexibility allows it to follow the contour of the workpiece, ensuring continuous contact and uniform pressure distribution across three-dimensional geometries, unlike rigid clamping mechanisms that create point contacts and non-uniform pressure.
3Stress or pressure
If a pressure-tight hood-type mat is used for reworking, then pressure can be applied, but the stability becomes inadequate leading to potential deformation
Solution Approach 1:
The fixing frame is designed with asymmetric, geometry-specific support structures that adapt to the particular shape and size of the workpiece. The frame includes adjustable legs and supports that can be positioned to provide optimal stability for each specific reworking operation, preventing deformation while maintaining pressure application. The asymmetric design allows customization to match the unique requirements of different fibre composite structures.
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
Enables high-quality, precise reworking or replacement of fibre composite structures with uniform pressure distribution, avoiding material deformation and the need for additional equipment, while using the same material and layer structure as the original component, thus reducing costs and time.
Implementation Method 1
A pressure mat (4) adapted to the contour of the reinforcement element (10) is then arranged over the at least one fibre layer (11) and/or the at least one replacement portion of the reinforcement element (10), the at least one pressure mat (4) being supported and fixed in a desired position by means of a fixing frame (3) adapted to the contour of the reinforcement element (10). A pressure medium is then applied to the at least one pressure mat (4) in order to press it against the reinforcement element (10) and the fixing frame (3).
Implementation Method 2
At least one heating element (6) adapted to the contour of the reinforcement element (10) is then arranged over the at least one pressure mat (4). The at least one heating element (6) is used to heat the at least one fibre layer (11) and/or the at least one replacement portion of the reinforcement element (10) to a curing temperature.
Data Source
AI summary
The invention relates to a method for at least partially reworking or replacing a reinforcement element of a fibre composite structure. In a first method step, at least one fibre layer is arranged on a surface section of the reinforcement element and/or at least one replacement section of the reinforcement element of the same material and same layer structure is arranged on a surface reinforcement section of the fibre composite structure. In a second method step, at least a pressure mat adjusted to the contour of the reinforcement element is disposed above the at least one fibre layer and/or the at least one replacement section of the reinforcement element, wherein the at least one pressure mat is supported and fixed in a nominal position by a fixing frame adjusted to the contour of the reinforcement element. In a third method step, the at least one pressure mat is then acted upon by a pressure medium in order to press the same against the reinforcement element and the fixing frame. In a fourth method step, a hardening of the at least one fibre layer and/or the at least one replacement section of the reinforcement element is carried out. The invention further relates to a corresponding connecting device for carrying out the method.