Variable Cross-Section Composite Preform Weaving
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Solution Overview
Problem
Existing methods for manufacturing dry woven preforms for composite materials, such as those used in aeronautical structural elements, face challenges like loss of fibers, deformation, and reduced mechanical strength due to the complexity of handling and cutting narrow folds, as well as the need for post-polymerization machining, which is costly and difficult to achieve precise dimensions.
Innovation Solution
A process that weaves fibers in a longitudinal direction with a constant number of warp threads over the length, allowing for simultaneous reduction or increase in width and height, using a change in weave pattern and comb tooth spacing to maintain continuity and mechanical strength, enabling a single operation to produce a preform with a finished, progressively varying section.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If flat folds of fabric are draped and deformed by twisting to change the plane, then the cross-section can be changed, but fiber loss at edges and significant deformation of folds occur
Solution Approach 1:
The loom is configured in advance with a variable tooth spacing comb that pre-establishes the desired cross-sectional evolution. The weaving process directly creates the evolved cross-section without subsequent deformation operations, preventing fiber loss that would occur during post-manufacturing twisting and folding operations.
Solution Approach 2:
The mechanical deformation process (twisting and folding after fabrication) is replaced by a weaving process that directly creates the evolved cross-section. The variable tooth spacing comb guides the warp threads to naturally form the desired shape during weaving, substituting post-manufacturing mechanical operations with an integrated fabrication approach.
2Shape
If flat folds of fabric are deformed by twisting to change the plane, then the cross-section can be changed, but significant deformation of folds and local disorientations of fibers occur
Solution Approach 1:
The loom configuration with variable tooth spacing pre-determines the final fiber orientation and cross-sectional shape during the weaving process itself. This eliminates subsequent deformation operations that would cause uncontrolled local disorientations of fibers, ensuring precise fiber orientation throughout the evolved section.
Solution Approach 2:
The tooth spacing of the comb is varied as a controlled parameter during the weaving process to directly achieve the desired cross-sectional evolution. This parameter change approach allows precise control over the final shape and fiber orientation, replacing uncontrolled mechanical deformation with a controlled fabrication process.
3Shape
If multiple narrow and slender folds of fabric are cut and handled, then the cross-section can be changed, but loss of rovings at edges and significant deformations occur
Solution Approach 1:
The final evolved cross-section is pre-configured in the loom setup with variable tooth spacing, allowing the preform to be manufactured in a single continuous weaving operation. This eliminates the need for subsequent cutting and handling of multiple narrow folds, greatly simplifying the manufacturing process and preventing edge losses.
Solution Approach 2:
The shape-changing operation is merged with the fabrication process itself. The variable tooth spacing comb integrates the cross-sectional evolution directly into the weaving operation, combining what would otherwise be separate manufacturing steps (weaving followed by cutting/deforming) into a single unified process.
4Shape
If warp threads are added successively to locally and progressively increase the number of layers, then the cross-section can be changed, but the absence of continuity of added wires greatly reduces mechanical strength
Solution Approach 1:
The weaving process maintains continuous warp threads throughout the entire evolution of the cross-section. The variable tooth spacing comb continuously guides the same warp threads as the cross-section changes, ensuring uninterrupted fiber continuity and maintaining high mechanical strength throughout the evolved section.
Solution Approach 2:
The tooth spacing parameter is continuously varied during weaving to achieve cross-sectional evolution while maintaining continuous warp thread paths. This continuous parameter change approach allows the cross-section to evolve without breaking or discontinuing the reinforcing fibers, preserving mechanical strength.
5Area of stationary object
If the number of weft yarns is reduced to increase the width, then the width increases, but the number of layers decreases
Solution Approach 1:
The tooth spacing of the comb is varied as a controlled parameter to directly control the cross-sectional evolution. By adjusting tooth spacing, the loom can simultaneously achieve width increase and maintain or adjust the number of layers, providing independent control over these geometric parameters during the weaving process.
Data Source
Figure 1~3
Figure 4A
Figure 4B
AI summary
The invention relates to a method for manufacturing a preform made of reinforcement fibers woven in a longitudinal direction. Said preform is provided so as to be impregnated with resin in order to form an elongate element having a variable transverse cross-section (20), simultaneously including a reduction (or increase) in width and an increase (or reduction) in height. Said variable cross-section comprises, along the length thereof, a consistent number (c) of continuous warp threads arranged in layers. Said method for reducing width comprises carrying out a change in weave, adding additional weft threads, and simultaneously drawing the teeth of the longitudinal beater reed closer together so as to increase the number of layers.