Co-cured CFRP Wingbox Stringers for Structural Integration
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Solution Overview
Problem
Designing aircraft wing structures that effectively utilize composite materials while meeting various structural requirements such as bird strikes, lightning strikes, and aerodynamic forces while maintaining cost and manufacturing efficiency remains challenging, as existing designs often rely on metallic structures and complex testing processes.
Innovation Solution
The implementation of a wing box design featuring outboard and center planked stringers made of Carbon Fiber Reinforced Polymer (CFRP) with varying fiber orientations and layer lengths, co-cured with a composite skin to enhance strength and reduce thickness, integrated into a unified monolithic composite part, allowing for efficient load distribution and structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If composite materials are used to reduce weight and increase strength, then weight decreases and strength increases, but manufacturing complexity and testing costs increase
Solution Approach 1:
The wing box is divided into multiple stringers that are individually manufactured and then assembled together with the skin panels. Each stringer can be separately optimized and manufactured, reducing overall manufacturing complexity while maintaining the weight and strength benefits of composite materials.
Solution Approach 2:
The skin panels and stringers are co-cured together in a single manufacturing process to form an integrated monolithic structure. This merging eliminates the need for separate assembly steps and fastening operations, reducing manufacturing complexity and testing requirements while maximizing structural efficiency.
2Strength
If metal designs utilize a large number of fastened components, then structural requirements are met, but weight increases and manufacturing cost increases
Solution Approach 1:
Adjacent stringers are merged into a single integrated stringer component with continuous fiber reinforcement. This eliminates the need for fasteners and joints between stringers, reducing weight while maintaining or improving structural strength through continuous load paths.
Solution Approach 2:
Composite materials with directional fiber reinforcement are used to achieve high strength-to-weight ratio. The fibers are oriented to carry primary loads, providing equivalent or superior strength to metal structures at significantly reduced weight.
3Ease of manufacture
If composite parts are integrated into a unitized design, then manufacturing cost decreases and weight decreases, but modeling and testing complexity increases
Solution Approach 1:
The unitized wing box is segmented into standardized modules (skin panels, stringers, ribs) that can be independently modeled and analyzed. This modular approach simplifies the modeling process while maintaining the manufacturing efficiency benefits of integrated construction.
4Strength
If layers of composite material overlap to create thicker sections, then strength increases, but thickness increases which is not desirable
Solution Approach 1:
Instead of increasing thickness in the vertical dimension to achieve strength, the design uses overlapping layers that extend in the longitudinal dimension along the skin. This distributes the strengthening effect along the length of the structure rather than concentrating it in thickness, maintaining aerodynamic efficiency while achieving required strength.
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 the creation of a lightweight, strong, and cost-effective aircraft wing structure that efficiently distributes loads and maintains structural integrity under various flight conditions, including bending and torsional stresses, without increasing the thickness of the composite skin or stringers.
Implementation Method 1
outboard planked stringers that are laterally oriented within the outboard section and are co-cured with the composite skin at the outboard section; and center planked stringers that are laterally oriented within the center section and are co-cured with composite skin at the center section
Data Source
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AI summary
Systems and methods are provided for integrating structural components of a wing box. One embodiment is a system that includes outboard planked stringers within an outboard section of a wing box and are co-cured with composite skin at the outboard section. Each outboard planked stringer of the outboard section includes planar layers of Carbon Fiber Reinforced Polymer (CFRP) that are parallel with the composite skin at the outboard section, have fiber orientations aligned to bear tension and compression applied to the wing box, and each extend a different distance along the composite skin at the outboard section. The system also includes center planked stringers within the center section and are co-cured with composite skin at the center section. Each center planked stringer of the center section includes planar layers of CFRP that are parallel with the composite skin at the center section, have fiber orientations aligned to bear tension and compression applied to the wing box, and each extend a different distance along the skin at the center section.