Curved Composite Profile Production via Single-Phase Bending
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Solution Overview
Problem
Current methods for producing curved composite material frames, such as aircraft fuselage sections, face challenges including low productivity, difficulty in achieving perfect contact between layers, fiber undulation, and increased external radii with decreased internal radii, leading to defects like bridging and increased production time and cost.
Innovation Solution
A method involving stacking layers of pre-impregnated fibers on a deformable mandrel and winding them around a bending tool along an axis of rotation, with a neutral fiber positioned between the last 0° sheet and the axis of rotation, allowing all layers to be bent and polymerized in a single phase, thereby reducing fiber undulation and improving contact between layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If multiple bending phases are carried out successively to produce curved profile from stacked strips, then the curved profile can be formed, but productivity is reduced due to the multitude of bending phases
Solution Approach 1:
The patent combines multiple bending operations into a single bending phase by stacking multiple strips with different fiber orientations onto one mandrel and bending them simultaneously. This merging of operations reduces the number of sequential bending phases from multiple steps to a single step, thereby improving productivity while maintaining the desired curved profile shape.
Solution Approach 2:
The patent applies preliminary action by pre-positioning multiple strips with different fiber orientations onto the mandrel before the bending operation. The strips are arranged and secured on the mandrel in advance, allowing all strips to be bent simultaneously in a single phase rather than requiring multiple sequential bending operations for each strip individually.
2Shape
If pre-impregnated fiber strips are stacked and bent sequentially, then curved profile can be formed, but relative positioning between bands becomes difficult to achieve
Solution Approach 1:
The patent merges multiple positioning operations into a single operation by stacking all strips onto one mandrel and bending them simultaneously. This eliminates the need for multiple sequential positioning operations and allows all strips to achieve their correct relative positions in a single bending phase, improving manufacturing precision.
Solution Approach 2:
The mandrel serves as an intermediary tool that facilitates the simultaneous positioning and bending of multiple strips. The mandrel provides a stable base that holds all strips in their correct relative positions during the single bending operation, enabling precise relative positioning between bands without requiring multiple adjustment operations.
3Quantity of substance
If strips are stacked with increasing external radii and decreasing internal radii, then more layers can be added, but bridging defect occurs where strips are not tightly pressed against each other
Solution Approach 1:
The patent changes the geometric parameters of the mandrel to maintain optimal contact conditions. By carefully designing the mandrel's cross-sectional dimensions and curvature radius, the patent ensures that all strips remain tightly pressed against each other and the mandrel surface, preventing bridging defects even when multiple layers are stacked. The mandrel's geometry is optimized to accommodate the increasing number of layers while maintaining uniform contact pressure.
4Shape
If strips are bent after compacting, then curved profile can be formed, but slippage between sheets occurs causing undulations or folds
Solution Approach 1:
The patent applies preliminary action by securing all strips to the mandrel before the bending operation. The strips are fixed in their positions on the mandrel in advance, which prevents slippage during the bending process. This preliminary securing of strips eliminates the occurrence of undulations or folds that would otherwise result from slippage during bending.
Solution Approach 2:
The mandrel acts as an intermediary that provides mechanical support and constraint during the bending operation. The mandrel's surface and structure prevent the strips from sliding relative to each other, maintaining stable fiber orientation throughout the bending process. The mandrel serves as a intermediary that transmits bending forces uniformly across all strips while preventing slippage and undulation.
5Temperature
If plies of first strip remain in contact with heated tool longer than plies of last insert strip, then heating can be maintained, but differential thermal exposure occurs causing quality variations
Solution Approach 1:
The patent merges the heating process into a single unified operation that simultaneously heats all strips to the same temperature. By bending and heating all strips at the same time in a single phase, the patent eliminates differential thermal exposure that would occur with sequential processing. All plies receive equal thermal exposure, ensuring uniform quality while maintaining efficient heating.
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 enhances productivity by bending all layers in a single phase, reduces defects like bridging and fiber undulation, and allows for larger web sizes, while maintaining precise fiber orientation and controlling resin aging, resulting in a more efficient and cost-effective production process.
Implementation Method 1
a deformable mandrel capable of deforming between a straight position and a curved position
Implementation Method 2
brought into contact against a heated tool having at the periphery radial sections with a profile complementary to the cross sections of the mandrel. Thus during bending, the strip is compressed and undergoes an increase in temperature
Implementation Method 3
polymerizing the assembly thus formed
Data Source
Figure 1~3
Figure 4~6
Figure 7~8
AI summary
The object of the invention is a method for producing a curved profile from a straight preform of pre-impregnated fiber webs, said method consisting of stacking webs on a deformable mandrel (22) and winding said mandrel and the stacked webs onto a bending tool around an axis of rotation, characterized in that said deformable mandrel comprises an extension (38) a portion of which is closer to the axis of rotation than the last layer of 0° oriented fibers stacked when the preform is placed on the mandrel and a neutral fiber (40) disposed at the level of this portion so that the neutral fiber is disposed between the last layer of 0° oriented fibers stacked when the preform is placed on the mandrel and the axis of rotation.