Hybrid Composite Curing Tool for Aggressive Thickness Transitions
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Solution Overview
Problem
Conventional metallic tools are inadequate for manufacturing composite material structures with abrupt thickness reductions, leading to porosity issues due to gaps and misalignments, which compromise the quality of CFRP components like stringers and torsion boxes in aircraft.
Innovation Solution
A hybrid tool with a metallic surface and an elastic surface is used, where the elastic surface is integrated with the metallic portion to match the shape of the composite material part, allowing for precise adaptation and reducing porosity by expanding to fill gaps during the curing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional metallic tools are used to cure composite material parts with abrupt thickness reductions, then manufacturing simplicity is maintained, but porosity problems occur due to gaps and misalignments between the tool and composite plies
Solution Approach 1:
The patent applies a flexible membrane element made of elastomeric material that can deform and adapt to the complex geometry of the composite part, including abrupt thickness reductions. This flexible membrane eliminates gaps between the tool and composite plies while maintaining structural integrity, resolving the contradiction between surface matching precision and tool complexity.
Solution Approach 2:
The tool combines rigid metallic portions for structural support with flexible elastomeric portions for surface adaptation, creating a hybrid composite tool structure. This composite approach allows the tool to maintain both structural rigidity and surface conformity, achieving high manufacturing precision without excessive complexity.
2Reliability
If metallic tooling is used for parts with thickness reductions steeper than 1:200, then device simplicity is maintained, but porosity and resin flow into gaps occur compromising part quality
Solution Approach 1:
The flexible membrane element conformally adapts to steep thickness transitions in the composite part, eliminating gaps where resin could flow and cause porosity. The membrane's flexibility allows it to follow aggressive thickness changes while maintaining continuous contact with the composite plies, ensuring part quality without requiring complex adjustable mechanisms.
Solution Approach 2:
The elastomeric membrane acts as an intermediary between the rigid metallic tool structure and the composite material, providing a compliant interface that eliminates gaps and prevents resin leakage while transmitting the necessary curing pressure and shape to the composite part.
3Manufacturing precision
If the tool contact surface is made entirely of rigid metallic material, then ease of manufacture is improved, but the tool cannot adapt to aggressive thickness changes causing gaps and porosity
Solution Approach 1:
The tool contact surface is segmented into distinct rigid metallic portions and flexible elastomeric portions, each performing different functions. The metallic portions provide structural support and are easier to manufacture, while the elastomeric portions provide surface conformity and adaptability, resolving the contradiction between manufacturing ease and contact surface conformity.
Solution Approach 2:
Different portions of the tool contact surface have different material properties: rigid metallic areas for structural stability and flexible elastomeric areas for surface adaptation. This local differentiation allows the tool to achieve high contact surface conformity without requiring the entire tool to be complex or difficult to manufacture.
4Measurement precision
If conventional metallic tooling is used, then device simplicity is maintained, but positioning tolerances and slippage cause misalignments between tool and ply stacks
Solution Approach 1:
The flexible membrane element eliminates slippage and misalignment by conformally adhering to the composite plies through its elastomeric properties. The membrane's ability to deform and maintain continuous contact ensures precise positioning accuracy without requiring complex positioning mechanisms or adjustment systems.
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 hybrid tool enables the successful manufacturing of composite structures with aggressive thickness changes, such as stringers, by preventing resin flow into gaps and ensuring high-quality production, even with significant thickness reductions, and can be reused without readjustment.
Implementation Method 1
an elastic portion provided on a surface of the metallic portion... the elastic surface is integrated with the metallic portion to match the shape of the composite material part, allowing for precise adaptation and reducing porosity by expanding to fill gaps during the curing process
Data Source
AI summary
A hybrid tool for curing composite structures for aircrafts, such as stringers, torsion boxes, skin panels, wing surfaces, horizontal tail or vertical stabilizers, etc. The hybrid tool comprises a metallic portion and an elastic portion arranged on a surface of the metallic portion. The elastic portion and the metallic portion are permanently joined to each other so that the metallic portion and the elastic portion together define a surface having a shape which copies at least part of a surface of a piece of composite material to be cured. The tool is capable of satisfactorily curing pieces of composite material which have a minimum thickness and/or a very aggressive change of thickness.