Compacted Stringer Packages via Collapsible Foam Mandrel
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional composite stringer manufacturing processes are hindered by large manufacturing footprints, lengthy assembly times, and difficulties in removing forming tools from composite structures with closed cross-sections, which limit production efficiency and increase costs.
Innovation Solution
A method involving a foam mandrel assembly with gas impermeable layers and a release layer, where a supportive foam mandrel collapses during curing under elevated temperature or pressure, allowing for the formation of compacted stringer packages with a hat-shaped cross-section, reducing tool complexity and assembly time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a large cure tool is used to form composite stringers and skin, then the composite structure can be formed, but the manufacturing footprint becomes large, limiting the quantity of cure tools that fit within a manufacturing environment
Solution Approach 1:
The patent divides the composite stringer assembly into multiple separate stringer components that can be manufactured and cured independently on smaller cure tools. Each stringer is formed as a discrete unit rather than requiring a single large cure tool for the entire assembly, thereby reducing the manufacturing footprint while maintaining the ability to form complex composite structures.
2Ease of manufacture
If multiple separate processes are performed to assemble composite stringers on the cure tool, then the composite stringers can be assembled, but the overall manufacturing time increases, limiting production quantity
Solution Approach 1:
The patent performs preliminary actions by pre-assembling and pre-curing individual stringer components before final assembly. The stringers are manufactured and cured as separate units in advance, allowing for parallel processing and reducing the time required for on-tool assembly operations. This preliminary preparation enables faster overall production while maintaining assembly quality.
3Manufacturing precision
If a solid mandrel is used to form composite structures with closed cross-section, then the composite structure can be formed, but the mandrel cannot be removed without a straight line of sight extraction path, making tool removal difficult
Solution Approach 1:
The patent employs a collapsible mandrel that transitions from a rigid support structure during curing to a compressed, removable form after curing. The mandrel is designed to maintain its structural integrity and support function during the curing process, then collapse or decompress to enable easy removal through the cured composite structure without requiring straight line of sight extraction paths.
Solution Approach 2:
The patent changes the physical parameters of the mandrel material or structure during the manufacturing process. The mandrel may undergo phase changes, density changes, or structural transformations that allow it to be rigid during curing and then become compressible or removable afterward. This parameter change enables the mandrel to fulfill its support function during manufacturing while facilitating easy removal afterward.
4Manufacturing precision
If even pressure is applied during curing of thermoset composite material, then fewer inconsistencies are produced in the composite structure, but the curing process requires precise temperature and pressure control
Solution Approach 1:
The patent employs a vacuum bag that serves multiple functions: it applies even pressure during curing, contains the composite material, and facilitates pressure distribution across the entire cured structure. This multi-functional tool simplifies the curing process control by combining several functions into a single system, reducing the complexity of coordinating multiple separate pressure application mechanisms while maintaining consistent pressure distribution.
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 enables more efficient manufacturing by reducing tool complexity, streamlining the assembly process, and facilitating easier extraction of forming tools from composite structures, thereby increasing production capacity and reducing costs.
Implementation Method 1
collapsing a supportive foam mandrel within the foam mandrel assembly during curing, wherein collapsing the supportive foam mandrel comprises drawing a vacuum within the foam mandrel assembly to collapse the supportive foam mandrel within the foam mandrel assembly during curing
Implementation Method 2
applying vacuum pressure to the stringer layup to form a compacted stringer package having a hat-shaped cross-section
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An illustrative embodiment of the present disclosure provides a method. A composite charge (204) is placed over a forming and cure mandrel (210), a first radius filler (207), and a second radius filler (208). Mechanical pressure is applied to shape the composite charge (204) to the forming and cure mandrel (210) and a rigid base (230) to form a stringer layup (232) having a hat-shaped cross-section. Vacuum pressure is applied to the stringer layup (232) to form a compacted stringer package.