Unitary Composite Grids with T-Shaped Cross-Sections
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Solution Overview
Problem
The challenge in aircraft manufacturing lies in efficiently forming composite structures with I-shaped cross-sections, particularly with unitized composite grids, which face issues of weight, manufacturing time, and complexity in tooling, as well as the need to avoid trapping tooling during curing, while minimizing the number of manufacturing steps and ensuring adequate bonding strength.
Innovation Solution
The solution involves forming a first and second unitary structure with T-shaped cross-sections, co-curing them to create a grid, and then forming joints between these grids using resin infusion and machining to create openings and protrusions for adhesive application, allowing for tool removal and improved bonding without trapping tooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If stiffeners are cured individually before fastening, then each stiffener achieves proper curing, but manufacturing time and resource consumption increase
Solution Approach 1:
The patent combines multiple stiffeners and skin panels into a single composite structure that is cured as one unit. The mold assembly includes multiple skin panels and stiffeners positioned together, allowing simultaneous curing of all components. This eliminates the need to cure each stiffener separately and then fasten them, thereby reducing manufacturing time while maintaining proper curing quality through the unified curing process.
2Strength
If fasteners are used to join stiffeners, then structural connection is achieved, but aircraft weight increases
Solution Approach 1:
The patent merges the stiffeners and skin panels into a single cured composite structure, eliminating the need for separate fasteners to join the stiffeners. The stiffeners are integrally formed with the skin panels through co-curing, which provides structural connection without adding the weight of fasteners. This weight reduction directly improves aircraft performance while maintaining structural integrity.
3Productivity
If unitized composite grids are formed, then manufacturing steps are reduced, but tooling complexity and trapping issues increase
Solution Approach 1:
The patent segments the mold into multiple removable skin panels that can be taken away independently after curing. This segmentation allows the mold to be disassembled without trapping any components, simplifying the tooling design while still enabling the formation of unitized composite grids. The stiffeners are designed with features that facilitate easy removal from the segmented mold, reducing tooling complexity.
Solution Approach 2:
The patent employs a dynamic mold design where skin panels can be moved and removed after curing. The mold includes features that allow for dynamic disassembly, enabling the removal of skin panels without trapping the cured composite structure. This dynamic approach simplifies tooling complexity while maintaining the productivity benefits of unitized manufacturing.
4Strength
If more manufacturing steps are used to ensure bonding strength, then joint strength is improved, but manufacturing time increases
Solution Approach 1:
The patent combines the bonding process with the curing process by using adhesive films that are applied to the bonding surfaces before co-curing. The adhesive bonds the stiffeners to the skin panels during the same curing cycle, eliminating the need for separate bonding steps. This integrated approach ensures adequate adhesive bond strength while minimizing manufacturing time by performing bonding and curing simultaneously.
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 method reduces weight, manufacturing time, and tooling complexity, while ensuring strong adhesive bonds and minimizing shear loads, thus enhancing the efficiency and performance of composite structure formation.
Implementation Method 1
forming a first and second unitary structure with T-shaped cross-sections, co-curing them to create a grid, and then forming joints between these grids using resin infusion
Data Source
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AI summary
Apparatus (700), and methodfor forming such apparatus, comprising a first unitary structure (602) , a second unitary structure (502), and a number of joints between the first unitary structure and the second unitary structure, wherein each of the first and second unitary structures has a plurality of T-shaped cross-sections.