Composite Fuselage Frame Wrinkle-Free Manufacturing
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Solution Overview
Problem
Conventional composite material pre-impregnation processes using straight fibers cannot produce arcuate structural components efficiently due to wrinkle formation when fibers are deformed, limiting fiber orientation and cross-sectional complexity, especially for Z-shaped fuselage frames.
Innovation Solution
A method using unidirectional prepreg tapes oriented at various angles, formed on a mandrel with specific bending techniques and promontory formations to prevent wrinkles, allowing for circumferentially oriented fibers and varied cross-sectional thicknesses, enabling the creation of Z-section frames without fiber deviation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If traditional prepregs with straight fibers are deformed to give an arcuate shape, then the component can be formed into curved geometry, but wrinkles inevitably form in the fibers where the radius of bend is smaller
Solution Approach 1:
The invention pre-forms the reinforcing fiber layers into arcuate shapes before impregnation with resin. The layers are shaped to match the desired final component geometry, with fibers already positioned in the correct arcuate arrangement. This preliminary shaping avoids the need to deform straight fibers during or after impregnation, thereby preventing wrinkle formation while achieving the required curved geometry.
Solution Approach 2:
The reinforcing structure is divided into multiple discrete layers that can be independently shaped and positioned. Each layer is formed separately with the appropriate arcuate geometry before being assembled into the final component. This segmentation allows precise control over fiber orientation in each layer without the constraints of continuous fiber deformation.
2Shape
If planar curved braided layers or spiral fabrics are used to make arcuate components, then the fibers can be arranged in curved patterns, but the fibers must be formed within the component geometry before impregnation, and unimpregnated fibers deviate easily from the original direction
Solution Approach 1:
The invention uses composite material structures where reinforcing fibers (such as carbon or glass fibers) are embedded within a resin matrix. The resin impregnation stabilizes the fiber arrangement, preventing deviation from the designed arcuate positions. The composite structure maintains the curved fiber geometry while providing dimensional stability that prevents fiber migration.
3Shape
If overbraiding technology is used to create arcuate preforms, then fibers can be woven in arcuate patterns, but the fiber orientation is restricted to a narrow range and cannot achieve 90° orientation
Solution Approach 1:
The reinforcing structure is divided into multiple discrete layers that can be independently shaped and positioned. Each layer is formed separately with the appropriate arcuate geometry before being assembled into the final component. This segmentation allows precise control over fiber orientation in each layer without the constraints of continuous fiber deformation.
4Shape
If overbraiding technology is used, then arcuate preforms can be created, but expensive supporting mandrels are required for transport and storage from fabric formation to use
Solution Approach 1:
The invention extracts the shaping function from temporary supporting mandrels and integrates it directly into the impregnation process. The component geometry is defined by the mold or tooling used during resin impregnation and curing, eliminating the need for separate fabric-forming mandrels. This removes the requirement for expensive supporting mandrels during transport and storage.
5Shape
If overbraiding technology is used, then arcuate components can be manufactured, but the cross sections are limited to C-type closed cross sections and cannot achieve varied thickness
Solution Approach 1:
The invention applies different fiber orientations, layer configurations, and thicknesses to different local regions of the component. Each section can be independently designed with the appropriate properties - for example, thicker sections where higher strength is required and thinner sections where weight reduction is prioritized. This local customization achieves varied cross-sectional thickness and complex geometries that overbraiding cannot produce.
Data Source
Figure 1~3
Figure 4A~7
Figure 8
AI summary
To manufacture an arcuate structural member (10) of a fuselage frame of composite material, tapes of resin pre-impregnated unidirectional fibres are used. The member (10) includes a web (11) lying in a radial plane and a radially outer cylindrical flange (12). Use is made of an elongate, arcuate forming mandrel (M1) having a flat radial surface (F) forming an angular edge (D) with a radially outer, convex cylindrical surface (S); and a series of promontories (P) radiating outwardly with respect to the cylindrical surface (S) are provided. A plurality of layers of pre-impregnated composite material are laid on the mandrel (M1) so as to form a first flat arcuate laminate (20'), with a part (20") of the laminate projecting radially outwardly beyond the angular edge (D). The mandrel (M1), the laminate (20') and the promontories (P) are covered with a membrane (E). A vacuum is then applied underneath the membrane, causing the membrane to urge the projecting part (20") of the laminate against the cylindrical surface (S) and against the promontories (P). In this way the projecting part, bent by the membrane, partially copies the shape of the cylindrical surface (S) of the mandrel in the intermediate areas between the promontories, whereas these prevent or retard the contact of the projecting part (20") with the cylindrical surface (S) near the promontories. Finally, discrete portions of the projecting part (20") near the promontories are removed, obtaining peripheral cavities (15) spaced apart from one another by flange lengths (22) in the form of cylindrical segments.