Composite Stiffener Geometry Control via Local Rigid Tooling
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Solution Overview
Problem
Existing techniques for manufacturing composite parts with stiffeners and skins face challenges in controlling the geometry of the stiffener and its bond to the skin, particularly in ensuring mechanical stability and preventing deformation during the manufacturing process.
Innovation Solution
An assembly structure comprising preforms and toolings, where a skin preform and an omega-shaped stiffener preform are positioned with local rigid stiffener toolings and a flexible envelope, allowing for precise control of geometry and mechanical stability through vacuum infusion and resin injection, ensuring accurate positioning and bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the omega stiffener is molded separately and joined to the skin in a second operation, then the geometrical control of the stiffeners is good, but the docking of the prefabricated part on the skin structure is difficult and the process is expensive
Solution Approach 1:
The patent merges the stiffener and skin into a single integrated molding operation. The assembly structure positions the stiffener preform on the skin preform within a single mold cavity, allowing both components to be formed and joined simultaneously. This eliminates the separate docking operation while maintaining geometric control through the rigid tooling and positioning mechanisms.
Solution Approach 2:
The patent introduces an intermediary assembly structure that includes positioning elements and tooling components. This intermediary structure facilitates the integration of stiffener and skin by providing precise positioning during molding, acting as a mediator between the separate components and the final integrated part.
2Ease of manufacture
If the stiffener is formed on the skin by surrounding a core, then the manufacturing process is simplified, but the control of the geometry of the stiffener and the geometry of the bond to the skin is difficult
Solution Approach 1:
The patent segments the tooling into distinct components: a rigid skin tooling for the skin preform and a local rigid stiffener tooling for the stiffener preform. This segmentation allows each component to be controlled independently with appropriate precision, while still forming them in an integrated operation. The segmented tooling provides better geometric control than a single core surrounding the entire assembly.
Solution Approach 2:
The patent applies local rigid tooling specifically to the stiffener region where precise geometric control is needed, while using a flexible envelope for the skin region. This local quality approach provides enhanced geometry control for the stiffener and its bond to the skin without requiring the entire mold to be rigid, thus simplifying the overall manufacturing process while maintaining precision where critical.
3Device complexity
If a flexible envelope is used to cover the stiffener tooling and skin preform, then the assembly is simplified, but the geometric control and fiber orientation in the connection area may be compromised
Solution Approach 1:
The patent combines flexible and rigid tooling components in a hybrid assembly structure. The flexible envelope provides simplicity and adaptability for the overall assembly, while local rigid stiffener tooling is positioned specifically in the connection area to maintain geometric control and proper fiber orientation. This local quality approach resolves the contradiction by applying rigidity only where precision is critical while maintaining overall assembly simplicity.
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 enhances the geometric control of composite parts, maintains the stiffener's shape, and reduces deformation risks, resulting in improved mechanical stability and surface quality.
Implementation Method 1
allowing for precise control of geometry and mechanical stability through vacuum infusion and resin injection
Implementation Method 2
through vacuum infusion and resin injection, ensuring accurate positioning and bonding
Data Source
AI summary
The invention relates to an assembly structure (10) for manufacturing a composite part. The structure comprises:—a skin preform (Pp) and a generally omega-shaped stiffener preform (PT) each having first and second opposing surfaces, the stiffener preform extending along and opposite the first surface of the skin preform. longitudinally and transversely in the form of a stiffener preform cross-section,—a rigid skin tooling (Op) disposed opposite the entire second surface (Sp2) of the skin preform,—a local rigid stiffener tooling (Or1, Or2) extending transversely around the stiffener preform cross-section with a transverse dimension smaller than the transverse dimension of the first surface of the skin preform.