Composite Wing Box Assembly With Bonded Overlapping Spars

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Solution Overview

Problem

Conventional aircraft wing assembly methods are time-consuming, heavy, and require numerous fasteners, which increase weight and assembly complexity, especially in hard-to-reach internal locations.

Innovation Solution

The use of unitary shell structures made from composite materials, bonded together with adhesive sections, forming overlapping spars and flanges to create a lightweight, durable wing structure, allowing for integrated equipment spaces and simplified assembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional drilling and riveting methods are used to join wing components, then structural strength is achieved, but the wing weight increases due to numerous fasteners and assembly complexity increases

Engineering Contradiction:
Improvestructural strengthVSAvoidwing weight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The patent replaces the mechanical fastening system (drilling holes and installing rivets) with a bonding system using adhesive. This substitution eliminates the need for numerous fasteners and their associated holes, thereby reducing wing weight while maintaining structural strength through the bonding action of the adhesive between shell structures and spars

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent employs composite material construction for the shell structures and spars, which inherently provides high strength-to-weight ratio. The combination of composite materials with adhesive bonding creates a lightweight yet structurally sound wing assembly, resolving the contradiction between achieving structural strength and minimizing wing weight

Inventive Principle:
Principle #40Composite materials

2Ease of operation

If manual joining methods are used for internal locations, then accessibility constraints are overcome, but assembly time increases significantly

Engineering Contradiction:
Improveaccessibility to internal locationsVSAvoidassembly time
Core Design Contradiction:
Ease of operationVSLoss of time

Solution Approach 1:

The patent replaces manual drilling and riveting operations with adhesive bonding, which can be applied more efficiently and requires less manual intervention in hard-to-reach areas. The bonding process can be performed with simpler equipment and less stringent accessibility requirements, thereby reducing assembly time while maintaining ease of operation for internal locations

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent divides the wing into modular shell structures that are assembled together through bonding. This segmentation allows for pre-assembly of components in accessible locations and simplifies the final assembly process, reducing the time required for manual joining operations in internal locations

Inventive Principle:
Principle #1Segmentation

3Reliability

If multiple discrete components are assembled with many fasteners, then structural integrity is achieved, but manufacturing complexity and production time increase

Engineering Contradiction:
Improvestructural integrityVSAvoidproduction time
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent replaces the multi-step mechanical fastening process (drilling, countersinking, installing rivets, tightening) with a single bonding operation using adhesive. This substitution maintains structural integrity through the bonding interface while dramatically reducing the number of assembly steps and production time required to manufacture the wing

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 solution results in a lightweight, strong, and easily assembled wing structure with reduced fastener use, enabling quicker production and integration of aircraft systems, while maintaining structural integrity and aerodynamic performance.

Implementation Method 1

The shell structures are bonded together via a plurality of discrete adhesive sections

Methodology Applied
Scientific EffectAdhesive bonding: Adhesive

Implementation Method 2

each shell structure comprising a partial front spar, a partial rear spar, a further partial spar and a wing skin... each further partial spar of each shell structure are arranged to overlap to form at least one further spar

Methodology Applied
Scientific EffectComposite materials: Composite Materials

Data Source

PatentEP4361025B1Aircraft wing structure
Publication Date: 2026.02.18 AIRBUS OPERATIONS LTD
  • EP4361025B1 patent drawingFigure 1~2
  • EP4361025B1 patent drawingFigure 3a~3b
  • EP4361025B1 patent drawingFigure 4~5

AI summary

An aircraft wing structure comprises first and second unitary shell structures 7, 8, preferably formed from a fibre-reinforced composite material. Each shell structure 7, 8 comprises a partial front spar, a partial rear spar and a wing skin. The partial front spars of each shell structure and the partial rear spars of each shell structure are arranged to overlap to form front and rear spars respectively. A wing box structure 6 constructed according to the invention is lightweight, strong and durable, with a lower overall part count than has been conventionally achievable. Aircraft systems equipment may be attached to the shell structures 7, 8 prior to, or after, assembly into a wing box.