Co-cured Duct Stringer Manufacturing via Mandrel Expansion
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Solution Overview
Problem
Existing duct stringer manufacturing methods for aircraft wings are inefficient and costly, particularly in providing a fluid transport system that effectively combines structural integrity with fluidic connections, such as venting and fuel transport, without adequate cost reduction and material optimization.
Innovation Solution
A method involving a hat-shaped structural member and a U-shaped channel member with co-bonded or co-cured joints, using a co-infusion process with dry-fibre preforms and a mandrel expansion mechanism to form a closed cross-section duct stringer, which is then adhered to a composite skin for enhanced structural and fluid transport capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional manufacturing methods are used for duct stringer, then structural integrity can be maintained, but manufacturing cost is high and efficiency is low
Solution Approach 1:
The patent combines the structural member and channel member into a single integrated component through co-curing or co-bonding processes. This merging eliminates the need for separate manufacturing and assembly operations, reducing manufacturing cost while maintaining structural integrity through unified construction.
Solution Approach 2:
The patent employs composite materials in the construction of both the structural member and channel member. This allows for optimized structural properties and fluid transport capabilities while reducing overall material cost and improving manufacturing efficiency through modern composite fabrication techniques.
2Ease of operation
If flanges are inserted without mandrel expansion, then assembly is simpler, but flanges snag on webs causing wrinkling
Solution Approach 1:
The mandrel is inserted into the channel member before the flanges are attached to the structural member. This preliminary positioning action ensures that the flanges are properly aligned and supported during assembly, preventing snagging and wrinkling while maintaining assembly simplicity through pre-established geometry.
Solution Approach 2:
The mandrel acts as an intermediary tool that facilitates the assembly process. By providing temporary support and defining the correct geometry during assembly, the mandrel enables both simple operation and high manufacturing precision without requiring complex alignment procedures.
3Ease of manufacture
If co-infusion process is used, then manufacturing cost is reduced, but process complexity increases
Solution Approach 1:
The co-infusion process merges the manufacturing of the structural member and channel member into a single integrated operation. Although the process itself is complex, combining the operations eliminates the need for multiple separate manufacturing steps, tooling setups, and assembly operations, ultimately reducing overall manufacturing cost.
Solution Approach 2:
The patent utilizes parameter changes in the infusion process, such as controlling resin flow rate, pressure, and temperature, to optimize the co-infusion of structural and channel members. By carefully managing these parameters, the process achieves cost reduction through integration while controlling the complexity through standardized process control.
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 reduces manufacturing costs and enhances the structural integrity and fluid transport efficiency of duct stringers, allowing for effective venting and fuel transport while preventing wrinkling and snagging issues during assembly.
Implementation Method 1
wherein a vacuum is applied so that the bladder is sucked by the vacuum into the concave sides of the support core, and the vacuum continues to be applied as the mandrel is inserted between the opposed inner faces of the webs; and wherein after insertion the mandrel is expanded by releasing the vacuum or applying a positive pressure so that the bladder is pushed away from the concave sides of the support core
Data Source
AI summary
A duct stringer is disclosed including a structural member with a hat-shaped cross-section. The structural member has a crown, a pair of webs and a pair of feet. A channel member with a U-shaped cross-section has a base and a pair of flanges. The flanges of the channel member are co-cured to opposed inner faces of the webs of the structural member. The structural member and the channel member together provide a duct with a closed cross-section which is adapted to transport fluid, for instance in an aircraft wing to provide a vent function in an aircraft fuel system.