Thin Thermostructural Composite Structure With Multilayer Spread Yarns
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Solution Overview
Problem
Existing methods for producing thin thermostructural composite material parts, such as those for aviation and space applications, face challenges in achieving uniform fiber preforms with sufficient mechanical properties and smooth surface finishes, often resulting in material loss and residual porosity due to the need for thick initial structures and irregular surface states.
Innovation Solution
A method involving multilayer weaving with a high number of layers and spreading yarns to reduce thickness, maintaining a fiber volume ratio of 25-45%, and using ceramic or carbon matrices to create parts with thicknesses less than 2 mm, while ensuring sufficient mechanical strength and surface quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If fiber preform is made by needling superposed layers to achieve thin thickness, then thickness is reduced, but uniform fiber distribution and mechanical properties deteriorate
Solution Approach 1:
The fiber reinforcement is segmented into multiple thin fabric layers (at least 5 layers) woven together to form a multilayer structure. This segmentation allows achieving thin overall thickness while maintaining uniform fiber distribution and mechanical properties through the woven architecture of each layer and their stacking sequence.
Solution Approach 2:
The invention uses a composite structure combining multiple fabric layers with different orientations (e.g., 0°, 45°, 90° plies) woven together. This composite multilayer fabric structure provides both the required thin thickness and sufficient mechanical strength through the synergistic arrangement of different fiber orientations and layers.
2Strength
If thick initial fiber structure is used to ensure uniform properties, then mechanical properties are improved, but material loss increases due to removing outer portions
Solution Approach 1:
The uniform fiber distribution and mechanical properties are built into the fiber preform during the multilayer weaving process itself, rather than requiring subsequent removal of material. The preliminary weaving action creates the desired uniform structure directly, eliminating the need to start with a thick structure and remove portions.
3Strength
If multilayer fabric with many layers is used to improve mechanical properties, then strength is improved, but thickness increases above 2 mm
Solution Approach 1:
The invention changes the parameters of the fabric construction by using at least 5 thin fabric layers with optimized areal weight and fiber arrangement. This parameter optimization allows achieving the required mechanical strength with a total thickness of at least 2 mm, resolving the contradiction between strength and thickness.
4Ease of manufacture
If conventional weaving is used to create fiber preform, then manufacturing is simplified, but surface finish becomes irregular
Solution Approach 1:
The invention applies different fabric layer configurations and weaving patterns to different regions of the preform as needed. By optimizing the local arrangement of fabric layers (e.g., different orientations, stacking sequences) in different areas, both manufacturing simplicity and surface finish quality are achieved through localized optimization rather than uniform construction throughout.
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 enables the production of thin composite parts with improved mechanical properties and reduced porosity, achieving thicknesses as low as 1 mm with a smooth surface finish, suitable for high-temperature applications like gas turbine afterbody parts and rocket engine exhaust cones.
Implementation Method 1
spreading yarns to reduce thickness
Implementation Method 2
polymerizing and pyrolyzing the resin in order to obtain a carbon or ceramic residue
Implementation Method 3
admitting a reaction gas into the enclosure under determined conditions in particular of pressure and temperature so that the gas diffuses into the preform and enables a deposit of the matrix material to be obtained as a result of one or more ingredients of the gas decomposing or as a result of a reaction between a plurality of its ingredients
Data Source
AI summary
A thermostructural composite material part including carbon or ceramic fiber reinforcement densified by a matrix having at least one thin portion in which: the thickness of the part is less than 2 mm, or indeed less than 1 mm; the fiber reinforcement is made as a single thickness of multilayer fabric made of spread yarns having a weight of not less than 200 tex; the fiber volume ratio lies in the range 25% to 45%; and the ratio between the number of layers of the multilayer fabric and the thickness in millimeters of the part is not less than four.