3D Reusable Curing Caul for Composite Edge Compaction
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Solution Overview
Problem
Conventional flexible cauls often result in non-conforming cure at the edges of stringers or stiffeners during the curing of integrated composite components due to improper edge ply compaction.
Innovation Solution
A three-dimensional shape-retentive curing caul formed from a one-piece resiliently fiber-reinforced body with a stiffened perimetrical edge region and a vertically spaced stiffened ridge region, coated with room temperature vulcanizing (RTV) silicone rubber, which expands during high-temperature curing to exert additional pressure and prevent edge non-conformance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional flexible caul is used during curing, then the caul can conform to the component shape, but edge ply compaction is insufficient causing non-conforming cure at stringer edges
Solution Approach 1:
The caul is constructed as a composite material system combining a flexible elastomeric base material with an integrated fiber-reinforced stiffening structure. The fiber reinforcement (such as glass fiber or carbon fiber) is embedded within the elastomeric matrix to create a hybrid structure that simultaneously provides flexibility for conforming to component shapes and rigid edge regions for effective ply compaction at stringer edges during curing
Solution Approach 2:
The caul features non-uniform structural properties with specifically designed stiffened edge regions that have different mechanical characteristics from the central flexible regions. The edge regions contain concentrated fiber reinforcement and may include raised profiles or beads that provide localized structural support and compaction force, while the central areas remain highly flexible to accommodate complex component geometries
2Manufacturing precision
If a fiber-reinforced elastomeric caul is used, then edge ply compaction is improved, but the caul structure becomes more complex
Solution Approach 1:
The manufacturing process combines multiple functions into a single integrated caul component. The fiber reinforcement, elastomeric matrix, stiffening structures, and sealing surfaces are all merged into one monolithic part formed in a single molding operation. This eliminates the need for separate flexible caul sheets, edge compression devices, and sealing elements that would otherwise be required as separate components
Solution Approach 2:
The caul utilizes changes in material parameters during the curing process. The elastomeric material exhibits temperature-dependent properties, becoming more compliant at curing temperatures to allow for better conformability, while the fiber reinforcement maintains structural integrity. The caul may also undergo controlled expansion or pressure changes during curing to optimize compaction forces at different stages
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
The curing caul effectively reduces or eliminates post-cure edge non-conformance of stringers or stiffeners by providing consistent pressure and maintaining the structural form, improving the quality of fiber-reinforced composite components.
Implementation Method 1
The elastomeric resin is a room temperature vulcanizing (RTV) silicone rubber... which expands during high-temperature curing to exert additional pressure
Implementation Method 2
The elastomeric resin is a room temperature vulcanizing (RTV) silicone rubber
Data Source
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AI summary
Curing cauls (10) formed of a one-piece three-dimensional resiliently shape-retentive fiber-reinforced body are provided, whereby the body includes a fibrous sheet (24) coated with at least one layer (22,26) of a cured elastomeric resin. The fibrous sheet (24) may be embedded within the cured elastomeric resin, with the body having a stiffened perimetrical edge region (12) and a stiffened ridge region (14) vertically spaced from the edge region (12).