Wing-Box Structure With Captive Rib Retention for Fastener-Free Assembly
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Solution Overview
Problem
Conventional wing-box assembly methods for aircraft are labor-intensive, require complex drilling and bolting, and are a barrier to high-rate production, with challenges in managing tolerances and lightning strike compatibility.
Innovation Solution
A wing-box structure that uses captive features on spars and covers to mechanically hold ribs in place during assembly, allowing for adhesive or weldable bonding without fasteners, enabling faster assembly and reduced weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional drilling and bolting methods are used to attach ribs to spars and covers, then structural connection strength is improved, but assembly complexity and labor intensity increase significantly
Solution Approach 1:
The patent replaces the mechanical drilling and bolting system with a captive feature retention system. The rib is retained by captive features formed as integral parts of the spar or cover, eliminating the need for separate fasteners. This substitution reduces assembly complexity while maintaining structural connection through the retention mechanism and bonding materials.
Solution Approach 2:
The patent merges the retention function into the spar or cover structure itself through captive features. Instead of using separate bolts and fasteners, the retention capability is integrated directly into the existing structural components, reducing the total number of parts and simplifying the assembly process while maintaining connection strength.
2Reliability
If thousands of fasteners are used to connect ribs to covers, then connection reliability is improved, but industrial lead time and production cost increase
Solution Approach 1:
The patent extracts and eliminates the fasteners from the assembly process. By using captive features that retain the rib without requiring separate fastening components, the system removes the source of production delays and cost increases associated with thousands of fasteners, while maintaining connection reliability through the retention mechanism.
Solution Approach 2:
The captive features are pre-formed as integral parts of the spar or cover during primary manufacturing. This preliminary preparation eliminates the need for subsequent fastening operations, reducing industrial lead time and enabling higher production rates while maintaining reliable connections through the pre-configured retention system.
3Strength
If fastener holes are drilled in covers and spars, then structural attachment is achieved, but lightning strike protection and weight are compromised
Solution Approach 1:
The patent replaces the mechanical fastening system with a captive feature retention system that does not require drilling holes through the cover or spar. This substitution eliminates the creation of conductive pathways through the structure, thereby maintaining lightning strike protection while achieving structural attachment through the retention mechanism and bonding.
4Manufacturing precision
If complex automated drilling and bolting equipment is used, then fastening precision is improved, but manufacturing cost and device complexity increase
Solution Approach 1:
The patent replaces the complex automated drilling and bolting equipment with a simpler captive feature retention system. The precision requirements are reduced because the rib is retained by features formed as integral parts of the spar or cover, eliminating the need for precision drilling and fastening operations, thereby reducing both equipment complexity and manufacturing cost.
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 assembly time, weight, and fuel burn emissions by eliminating fastener holes and complex tooling, while improving lightning strike protection and enabling higher production rates.
Implementation Method 1
adhesive or weldable material for bonding the rib to the forward and rearward spars and/or the upper and lower covers
Implementation Method 2
adhesive or weldable material for bonding the rib to the forward and rearward spars and/or the upper and lower covers
Data Source
AI summary
A wing-box structure for an aircraft is disclosed having an upper cover, a lower cover, longitudinal forward and rearward spars, and a plurality of transverse ribs. One of the transverse ribs is retained by a pair of opposed captive features disposed on an interior side of either the forward and rearward spars or the upper and lower covers. The rib is bonded rib to the forward and rearward spars and/or the upper and lower covers at a location where the rib is retained.