Composite Control Surface Crossbeam Supports for Torsional Stiffness
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Solution Overview
Problem
Existing methods for forming composite control surfaces in aircraft do not adequately address the need for sufficient structural integrity to withstand operational forces, particularly in the fore and aft directions, and require improvements in stiffness and torsional strength.
Innovation Solution
A method involving the use of fiber-reinforced materials with thermoset resin, where stiffening structures are sandwiched between skin members, and a triangular prism-shaped mandrel is used to form a fiber-reinforced control surface, allowing for heat and pressure application to consolidate the parts, and triangular mandrels are removed after curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If skin members are used to transmit load and provide stiffness in fore and aft direction, then the control surface can be formed using RPM, but the structural integrity and torsional strength are insufficient to withstand operational forces
Solution Approach 1:
The control surface is divided into multiple discrete stiffening structures (crossbeam supports) positioned at specific locations between the skin members, rather than using a continuous internal framework. Each stiffening structure is formed separately using individual mandrels and then assembled into the final structure, allowing for simplified manufacturing while providing distributed structural reinforcement throughout the control surface.
Solution Approach 2:
The stiffening structures are constructed using fiber-reinforced composite materials (such as carbon fiber or glass fiber reinforced polymers) that provide high strength-to-weight ratio and superior torsional stiffness. These composite stiffening structures are embedded between the skin members and bonded together with resin, creating a multi-material composite structure that significantly enhances structural integrity without excessive weight or complexity.
2Strength
If multiple fiber-mandrel sections are stacked to form stiffening structures, then torsional strength is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The manufacturing process segments the formation of stiffening structures into independent steps, where each stiffening structure is formed around its own mandrel separately. This allows for standardized, repeatable manufacturing of individual components that can then be assembled, reducing overall process complexity despite the multi-step nature of the manufacturing.
Solution Approach 2:
Mandrels serve as temporary intermediary structures that simplify the manufacturing process by providing a form around which fiber plies can be easily deposited and shaped. The mandrels are removed after curing, leaving behind the desired stiffening structure geometry. This intermediary approach makes the complex task of forming hollow, structurally optimized stiffening structures much easier to execute.
3Strength
If fiber plies are deposited around mandrels to form stiffening structures, then stiffness and torsional integrity increase, but the number of manufacturing steps increases
Solution Approach 1:
The manufacturing process is segmented into independent, parallelizable steps where multiple fiber-mandrel assemblies can be prepared simultaneously. Each stiffening structure is formed separately around its mandrel, allowing for concurrent manufacturing of multiple components before final assembly, thereby maintaining productivity despite the detailed multi-step process.
Solution Approach 2:
The fiber plies are deposited around the mandrels in advance, forming pre-assembled stiffening structure packages that are then cured and later integrated into the final control surface. This preliminary formation of stiffening structures allows for optimized fiber placement and resin infusion before final assembly, improving manufacturing efficiency by preparing components separately and assembling them in a controlled manner.
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 method enhances the structural integrity and increases the stiffness and torsional integrity of the composite parts, and torsional strength of the control surfaces, thereby improving their ability to withstand operational forces.
Implementation Method 1
consolidate the first fiber ply with the plurality of stiffening structures and the second fiber ply
Implementation Method 2
curing the part layup may comprise crosslinking a first resin of the first fiber-mandrel section with a second resin of the second fiber-mandrel section
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A control surface (100) for an aircraft comprise a first skin (110), a second skin (112) bonded to the first skin (110), and a stiffening structure (114) located between the first skin (110) and the second skin (112). The stiffening structure (114) may be formed by forming a plurality of fiber-mandrel sections (420, 422, 424, 426), stacking the plurality of fiber-mandrel sections (420, 422, 424, 426) to form a fiber-mandrel assembly (430), and depositing an outer fiber ply (320a, 320b, 320c) around a perimeter of the fiber-mandrel assembly (430). The control surface (100) may be formed by forming a part layup (210) over a first mold surface (206), contacting the part layup (210) with a second mold surface (214), and curing the part layup (210). Forming the part layup (210) over a first mold surface (206) may include locating a first fiber ply (202) over the first mold surface (206), locating a plurality of stiffening structure assemblies (200) over the first fiber ply (202), and locating a second fiber ply (208) over the plurality stiffening structure assemblies (200).