Composite Box Structure with Dense Packs for Aircraft Load Management
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Solution Overview
Problem
Existing composite aircraft transport wing and stabilizer box structures require extensive manual labor and time for assembly, use numerous heavy mechanical fasteners that increase weight and fuel costs, and may compromise structural efficiency due to traditional load distribution methods.
Innovation Solution
The development of a bonded box structure using upper and lower composite integrated sandwich panels with dense packs and spars, where facesheets carry torsion and pressure loads in shear, and dense packs carry axial bending loads, reducing the need for internal frameworks and fasteners.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If numerous mechanical fasteners are used to join box sections, then structural strength and stability are improved, but weight increases and fuel efficiency deteriorates
Solution Approach 1:
The patent replaces mechanical fasteners with adhesive bonding to join box sections. The adhesive bonds the composite skin to the internal framework and connects adjacent box sections, eliminating the need for numerous mechanical fasteners while maintaining structural integrity. This substitution reduces weight and improves fuel efficiency while preserving the required structural strength.
2Stability of the object's composition
If numerous mechanical fasteners are used to join box sections, then structural stability is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent replaces complex mechanical fastening systems with simpler adhesive bonding processes. The adhesive is applied to the skin and internal framework, eliminating the need for drilling, inserting, and tightening numerous fasteners. This reduces manufacturing complexity, labor requirements, and assembly time while maintaining structural stability through proper adhesive bonding design.
3Stability of the object's composition
If traditional semi-monocoque load distribution is used with skins and stringers, then structural stability is maintained, but part count and manufacturing complexity increase
Solution Approach 1:
The patent merges the functions of skins and stringers into an integrated composite box structure. The composite skin itself is designed to carry bending and torsional loads, eliminating the need for separate stringer elements. The internal framework provides localized reinforcement where needed, but the overall load distribution is achieved through the integrated box structure design, reducing part count and simplifying manufacturing.
4Strength
If numerous fasteners are installed through outer composite skin panels, then structural joining is achieved, but lightning strike risk increases
Solution Approach 1:
The patent replaces mechanical fasteners that penetrate the composite skin with adhesive bonding that bonds to the skin surface or embedded features without penetration. This eliminates conductive paths through the skin that could facilitate lightning strike damage, while maintaining joining strength through properly designed adhesive bonds that accommodate thermal expansion and structural loads.
Data Source
AI summary
There is provided a box structure for carrying load having upper and lower composite integrated sandwich panels. The panels have facesheets sandwiching one or more core portions and adjacent dense packs oriented in an axial direction. The box structure further has a plurality of spars. Each spar has a web and web attachments and has a spar length in the axial direction. The plurality of spars are connected to the panels with the web attachments located at the dense packs. The facesheets are configured to carry primarily torsion and pressure loads in shear and no significant axial loads. The dense packs are configured to carry all significant box bending in axial tension and compression loads.