Flexible Composite Mandrel for Aircraft Stringer Curing
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Solution Overview
Problem
Current composite manufacturing processes using metal mandrels often result in poor laminate quality due to stiffness issues, leading to web wrinkle defects and increased costs, and are ergonomically challenging and time-consuming, especially when forming long aircraft structures like stringers.
Innovation Solution
A composite manufacturing system employing flexible mandrels composed of pre-cured composite planks and layers of flexible material, which deform under pressure to prevent laminate inconsistencies and allow for ergonomic and efficient processing, using a single vacuum bag to reduce manufacturing time and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal mandrels are used for forming composite structures, then the mandrels can withstand manufacturing conditions and provide structural support, but the stiffness of metal mandrels causes gap conditions between composite material layers resulting in poor laminate quality
Solution Approach 1:
The mandrel is constructed as a composite structure with alternating layers of composite planks and flexible material layers. This composite construction allows the mandrel to provide structural support while maintaining flexibility to conform to the composite material being formed, eliminating gap conditions and improving laminate quality.
Solution Approach 2:
The flexible material layers are positioned at specific intervals between the composite planks, creating local flexibility zones that allow the mandrel to adapt to the composite material contours while maintaining overall structural integrity for withstanding manufacturing conditions.
2Strength
If metal mandrels are used for forming long aircraft structures, then structural support is provided, but the process becomes ergonomically challenging and time-consuming
Solution Approach 1:
The composite construction of the mandrel with flexible material layers reduces the overall weight and increases flexibility compared to solid metal mandrels, making them easier to handle, position, and manipulate during the forming process, thereby improving ergonomic conditions.
3Manufacturing precision
If multiple vacuum bags are used for curing composite structures, then complete coverage and proper curing pressure are achieved, but manufacturing time and costs increase
Solution Approach 1:
The flexible material layers within the mandrel structure allow for better distribution of curing pressure and improved conformity to the composite part geometry, enabling effective curing with fewer vacuum bags and reducing manufacturing time while maintaining curing quality.
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 system achieves high-quality laminates by allowing mandrels to flex and twist, reducing inconsistencies, and enables ergonomic handling and faster processing with reduced risk of injury and cost, tailored to specific stiffness needs for aircraft parts.
Implementation Method 1
a vacuum applies pressure to contour the composite material against the tool
Implementation Method 2
layers of flexible material positioned between and bonded to the cured composite planks... During curing, the tool deforms to prevent poor laminate qualities
Data Source
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AI summary
A composite manufacturing system (202) for aircraft structures is provided. The composite manufacturing system comprises a tool (210) for forming a composite structure, a vacuum bag (212), and a tool base (211). The tool comprises cured composite planks (222) and layers of flexible material (224). The cured composite planks (222) run parallel to each other. The layers of flexible material (224) are positioned between and bonded to the cured composite planks (222). The vacuum bag (212) surrounds the tool and is configured to apply pressure to the tool during curing of the composite structure. The tool is configured to deform in response to the pressure and prevent poor quality laminate and/or anomalies from developing in the composite structure during curing. The tool base (211) is configured to hold the tool (210) in place as it deforms.