Flexible Mandrel Forming for 3D Wing Skin Stiffeners
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Solution Overview
Problem
Current methods for creating mandrels to form stiffeners for three-dimensional vehicle panels, such as aircraft wing skins, are inadequate due to the use of stiff materials that are difficult and expensive to manufacture, leading to incomplete or suboptimal stiffeners being used, especially for complex shapes.
Innovation Solution
A method involving flexible mandrels made of materials like silicone rubber, inserted into channels of a tool with a three-dimensional contour, hardened using substances like fiberglass resin, and then wrapped with stiffener material to form discrete three-dimensional stiffeners, such as I-, J-, and blade stiffeners, using a vacuum bag and hardening process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal or stiff materials are used to make mandrels, then the mandrels have high strength and rigidity, but they are difficult and expensive to manufacture into complex three-dimensional shapes
Solution Approach 1:
The patent changes the material parameter from stiff metal to flexible material (such as silicone rubber), enabling the mandrel to be easily formed into complex three-dimensional shapes while maintaining sufficient strength through the flexible material's properties and the vacuum bagging process
Solution Approach 2:
The patent uses composite construction where a flexible material forms the mandrel body, and a hardening substance is injected to create a composite structure that combines the ease of forming flexible material with the strength of hardened material, resolving the contradiction between manufacturability and strength
2Stability of the object's composition
If metal or stiff materials are used to make mandrels, then the mandrels maintain their shape well, but they are impossible to use for certain complex stiffener shapes
Solution Approach 1:
The patent changes the flexibility parameter of the mandrel material, allowing it to be inserted and conform to complex three-dimensional contours that rigid metal mandrels cannot accommodate, while the vacuum bagging process ensures the mandrel maintains its shaped configuration
Solution Approach 2:
The patent makes the mandrel dynamically adaptable by using flexible material that can be inserted into and conform to various complex shapes, then stabilized through the hardening process, enabling the same mandrel system to handle multiple complex geometries
3Ease of manufacture
If flexible mandrels are used, then the mandrels can be easily formed into complex shapes and are cost-effective, but they require additional hardening processes
Solution Approach 1:
The patent merges the mandrel forming process with the hardening process by injecting the hardening substance directly into the flexible mandrel while it is in position, combining two separate operations (forming and strengthening) into one integrated process that reduces overall complexity
4Strength
If traditional metal mandrels are used, then the manufacturing cost is high, but the mandrels provide sufficient strength for stiffener formation
Solution Approach 1:
The patent employs disposable or reusable flexible mandrels made from inexpensive materials like silicone rubber, which can be easily manufactured or replaced, significantly reducing the cost compared to expensive metal mandrels while providing sufficient strength through the combined flexible material and hardening substance structure
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 allows for the cost-effective creation of mandrels suitable for forming complex three-dimensional stiffeners, improving tolerance and enabling the use of optimal stiffeners on contoured sections of vehicle panels, reducing manufacturing costs and enhancing the quality of stiffener production.
Implementation Method 1
A vacuum bag is placed over the flexible mandrels and the tool, with the mandrels disposed between the vacuum bag and the tool, and vacuum pressure is applied between the vacuum bag and the tool
Implementation Method 2
A hardening substance is inserted into each of the plurality of flexible mandrels and then may be hardened while the plurality of mandrels are inserted in the one or more channels of the tool
Data Source
AI summary
In one embodiment, a stiffener may be formed by inserting a plurality of flexible mandrels into a channel of a tool having a three-dimensional contour, placing a vacuum bag over the flexible mandrels and the tool, with the mandrels disposed between the vacuum bag and the tool, and applying vacuum pressure between the vacuum bag and the tool. A hardening substance may be inserted into each of the plurality of flexible mandrels and then may be hardened while the plurality of mandrels are inserted in the one or more channels of the tool. Finally, the mandrels may be wrapped with a stiffener material with stiffeners being formed from the stiffener material.