3D-Printed Inflatable Mandrel for Complex Composite Inner Shapes
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Solution Overview
Problem
Manufacturing composite parts with complex inner shapes is labor-intensive and difficult due to the limitations of existing mandrel-based methods, particularly in creating features like undercuts and complex manifold shapes.
Innovation Solution
A single-use mandrel is manufactured via additive processes using a thermoplastic material with a glass transition temperature, coated with an elastomer, which is expanded within a mold to press fibers against the mold surface, allowing complex shapes to be formed, and then melted or dissolved for removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional elastic/thermoplastic tube-like cores are used for hand-laying carbon fibers, then the manufacturing process can be performed with simple equipment, but the process becomes labor-intensive and time-consuming with large effort required
Solution Approach 1:
The patent replaces the manual mechanical process of hand-laying carbon fibers with an automated resin infusion process. The mandrel is pressurized to force resin through the fiber preform, automatically impregnating the fibers without manual intervention. This substitution of mechanical automation for manual labor significantly reduces labor intensity and manufacturing time while maintaining process simplicity.
2Ease of manufacture
If traditional tube-like cores are used for vacuum bagging, then the process can be performed with standard equipment, but complex manifold shapes and undercuts are very hard or impossible to realize
Solution Approach 1:
The patent changes the physical state and properties of the mandrel material through temperature and pressure parameters. The mandrel is heated above the glass transition temperature of the thermoplastic material, causing it to soften and become more compliant. This parameter change allows the mandrel to expand and conform to complex mold geometries, enabling the production of parts with undercuts and complex manifold shapes that would be impossible with rigid traditional cores.
Solution Approach 2:
The patent uses a composite mandrel structure combining a thermoplastic core material with an elastomeric coating. The thermoplastic core provides structural integrity and pressure containment, while the elastomeric coating allows for expansion and conformability to complex shapes. This composite material approach enables the mandrel to achieve complex geometries while maintaining structural functionality.
3Manufacturing precision
If the mandrel is heated to expand and press fibers against the mold, then complex shapes can be formed, but the mandrel material must withstand the heating without deforming prematurely
Solution Approach 1:
The patent utilizes the glass transition phase transition of the thermoplastic mandrel material. The mandrel is heated to a temperature above the glass transition temperature but below the melting temperature, causing the material to transition from a rigid glassy state to a more compliant rubbery state. This phase transition enables the mandrel to expand and conform to the mold geometry while maintaining sufficient structural stability to contain pressure and support the fiber preform during the forming process.
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
Enables the production of composite parts with intricate inner structures by eliminating the need for vacuum bags and reducing mold preparation time, while allowing for the creation of features like undercuts and complex manifold geometries.
Implementation Method 1
a thermoplastic material that exhibits a glass transition at a glass transition temperature
Implementation Method 2
removing the mandrel by melting the mandrel wall
Data Source
AI summary
A mandrel is 3D-printed from a thermoplastic material that exhibits a glass transition. The mandrel has a mandrel wall made from the thermoplastic material and a cavity. The mandrel is coated with an elastomer coat and a fiber material is arranged on the elastomer coat. A composite part is formed from the fiber material by inserting the mandrel into a mold, pressurizing the mandrel, and heating the mold to a mold temperature greater than the glass transition temperature without melting the mandrel wall. The mandrel expands and presses the fiber material against the mold. The composite part is cured by increasing the mold temperature and simultaneously melting the mandrel wall.