Stringerless Sandwich Fuselage Panels With Foam-Filled Edge Transitions
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Solution Overview
Problem
Traditional manufacturing of stiffened stringer panels for aircraft is labor and tooling intensive, requiring extensive factory space and time, and involves complex processes for handling and aligning large support structures, which increases costs and reduces manufacturing efficiency.
Innovation Solution
The use of sandwich fuselage panels with a foam adhesive core structure, comprising an outer and inner skin member with a honeycomb core, where the foam adhesive expands to fill the cavity, eliminating the need for support structures like stringers and reducing tooling requirements, by providing structural integrity and weight optimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional stiffening members (stringers) are used in aircraft fuselage construction, then structural strength is improved, but manufacturing complexity and labor requirements increase significantly
Solution Approach 1:
The patent removes the traditional stringer stiffening members from the fuselage structure and replaces them with a sandwich panel construction consisting of outer and inner skins with a foam core. This extraction eliminates the need for separate stiffening components while maintaining structural integrity through the sandwich panel design itself.
Solution Approach 2:
The invention employs composite material construction by combining different materials (outer skin, inner skin, and foam core) into a sandwich panel structure. This composite approach provides the necessary structural strength and stiffness without requiring additional metal stringers, thereby reducing manufacturing complexity.
2Manufacturing precision
If traditional manufacturing processes with extensive tooling are used, then structural precision is maintained, but production time and factory space requirements increase
Solution Approach 1:
The foam core material is applied in its uncured state between the outer and inner skins before final assembly. The foam then expands and cures in place, automatically conforming to the cavity shape and providing precise structural geometry without requiring extensive post-manufacturing tooling or adjustments.
Solution Approach 2:
The foam adhesive undergoes parameter changes during curing, transitioning from a liquid or semi-liquid state to a solid expanded foam structure. This phase change allows the material to expand and fill the cavity completely, achieving precise dimensional accuracy and structural fit without requiring complex manufacturing tooling.
3Weight of moving object
If foam adhesive is used to fill the cavity between skins, then structural integrity is maintained with reduced weight, but adhesive application precision must be increased
Solution Approach 1:
The foam adhesive material possesses self-service characteristics by automatically expanding to fill the entire cavity between the outer and inner skins. This self-expanding property eliminates the need for precise manual application or complex dispensing equipment, as the foam naturally conforms to the available space and provides uniform structural support.
Solution Approach 2:
The foam adhesive undergoes a phase transition from a low-viscosity liquid or semi-liquid state during application to an expanded solid foam structure during curing. This phase change enables the adhesive to automatically fill the cavity and achieve the required structural integrity without demanding high precision in the initial application process.
4Ease of manufacture
If stringers and support members are eliminated, then manufacturing cost and labor are reduced, but alternative structural solutions must be developed
Solution Approach 1:
The invention merges the functions of the outer skin, inner skin, and foam core into a unified sandwich panel structure. This integration combines the structural roles of traditional skin and stiffening members into a single composite component, eliminating the need for separate stringers and support members while simplifying manufacturing.
Solution Approach 2:
The sandwich panel structure performs multiple functions simultaneously: the outer and inner skins provide aerodynamic surfaces and structural boundaries, while the foam core provides stiffening, insulation, and load distribution. This multi-functionality replaces the specialized roles of traditional stringers and support members, reducing overall structural complexity.
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 time, increases production rate, and maintains structural strength by eliminating the need for support structures, while allowing for precise fit and variable density distribution within the panel, enhancing edge strength and reducing material handling challenges.
Implementation Method 1
A cured foam adhesive occupies a center portion of the cavity. The density of the cured foam adhesive in the first transition portion gradually increases from the center portion to the first edge, and a density of the cured foam adhesive in the second transition portion gradually increases from the center portion to the second edge.
Data Source
Figure 1
Figure 2A
Figure 2B~2C
AI summary
Provided are sandwich panel assemblies. Specifically, a sandwich fuselage panel comprises an outer skin member (302) and an inner skin member (304) coupled to the outer skin member (302) at a first edge (230-A) and a second edge (230-B), forming a cavity (220) comprising a center portion (222), a first transition portion (224-A) extending from the center portion (222) to the first edge (230-A), and a second transition portion (224-B) extending from the center portion (222) to the second edge (230-B). A cured foam adhesive (532) occupies each of the first transition portion (224-A) and the second transition portion (224-B) of the cavity (220). A core structure (610), such as a honeycomb structure may occupy the center portion (222) of the cavity (220). Alternatively, the cured foam adhesive may occupy the center portion of the cavity. The density of the cured foam adhesive (532) in the transition portions may gradually increase from the center portion to the respective edge. The cured foam adhesive may comprise a polymer foam adhesive.