Welded Aircraft Torsion Box Structure With Hollow Profiles

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Solution Overview

Problem

Aircraft torsion boxes have a high weight and require numerous assembly operations and sealing, leading to high manufacturing costs and low production rates due to their complex structure and high number of parts.

Innovation Solution

A torsion box design featuring hollow profiles and stiffening ribs arranged alternately, with welding techniques such as friction welding or laser welding used to connect the parts, reducing the need for bolts and rivets and eliminating sealing operations, and utilizing extrusion for manufacturing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If traditional assembly methods with bolts and rivets are used to construct torsion boxes, then structural strength and reliability are improved, but device complexity and manufacturing cost increase significantly

Engineering Contradiction:
Improvestructural strengthVSAvoidnumber of parts
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent merges multiple separate components (profiles, stiffening ribs, sealing elements, fasteners) into an integrated welded structure. The hollow profiles and stiffening ribs are welded directly to each other to form a unified torsion box assembly, eliminating the need for separate sealing elements and fasteners, thereby reducing part complexity while maintaining structural integrity

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent replaces mechanical fastening systems (bolts, rivets, seals) with a welding system. Instead of using threaded fasteners and gaskets to join components, the invention uses welding to create permanent bonds between the hollow profiles and stiffening ribs, simplifying the assembly process and reducing the number of parts required

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

2Reliability

If traditional assembly methods with multiple sealing operations are used, then sealing reliability is improved, but productivity and manufacturing speed decrease

Engineering Contradiction:
Improvesealing reliabilityVSAvoidproduction rate
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent replaces mechanical sealing systems with a welding-based sealing approach. The welding process creates both structural joints and sealing interfaces simultaneously, eliminating the need for separate sealing operations and gaskets, thereby improving productivity without compromising sealing reliability

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

Solution Approach 2:

The patent combines structural joining and sealing functions into a single welding operation. The weld joints serve dual purposes: providing mechanical strength and creating sealed interfaces between components, thereby eliminating separate sealing steps and improving manufacturing efficiency

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If numerous fasteners and fixing members are used to assemble torsion boxes, then assembly reliability is improved, but the mass of the structure increases

Engineering Contradiction:
Improveassembly reliabilityVSAvoidmass of torsion box
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The patent replaces heavy mechanical fastening systems with a lighter welding system. By using welding to join the hollow profiles and stiffening ribs, the invention eliminates the need for numerous bolts, rivets, and other fasteners, significantly reducing the overall mass of the torsion box while maintaining assembly reliability through strong welded joints

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

4Strength

If complex assembly operations with many fixing members are used, then structural integrity is improved, but manufacturing cost and time increase

Engineering Contradiction:
Improvestructural integrityVSAvoidmanufacturing cost
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The patent replaces complex mechanical assembly operations with a simpler welding process. The welding system can automatically join multiple components in sequence, reducing the need for manual alignment, fastener installation, and sealing operations, thereby lowering manufacturing costs while maintaining structural integrity

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

Solution Approach 2:

The patent combines multiple manufacturing operations (structural joining, sealing, fastening) into a single welding process. This integration reduces the total number of manufacturing steps, decreases labor requirements, and lowers overall manufacturing cost while ensuring structural integrity through continuous welded joints

Inventive Principle:
Principle #5Merging (Combining)

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 design simplifies the manufacturing process, reduces the mass of the torsion box by 30%, and increases production rates by a factor of 10, while significantly decreasing the number of parts and assembly operations.

Implementation Method 1

welding each of the two sole edges of the sole of each stiffening rib to a corresponding profile edge of a corresponding hollow profile, by means of a welding technique

Methodology Applied
Scientific EffectWelding: Welding

Implementation Method 2

step A has the manufacture of hollow profiles by extrusion

Methodology Applied
Scientific EffectExtrusion: Extrusion

Implementation Method 3

The edge-to-board welding technique is chosen from mixing friction welding and laser welding

Methodology Applied
Scientific EffectFriction welding: Friction Welding

Implementation Method 4

The edge-to-board welding technique is chosen from mixing friction welding and laser welding

Methodology Applied
Scientific EffectLaser welding: Laser Beam Welding

Data Source

PatentEP3536605B1Torsion box for aircraft made up of items welded two by two and method for manufacturing same
Publication Date: 2021.07.21 AIRBUS OPERATIONS (SAS)
  • EP3536605B1 patent drawingFigure 1~2
  • EP3536605B1 patent drawingFigure 3~5
  • EP3536605B1 patent drawingFigure 6~7

AI summary

An aircraft torsion box (60) comprises alternating hollow profiles (10) and stiffening ribs (12), each hollow profile having two opposing profile edges (24A, 24B) and two opposing openings circumscribed by the two profile edges respectively, each hollow profile completely enclosing an internal space connecting the two openings, and each stiffening rib comprising a web and a flange (32) extending from the web all around it, and having two flange edges (38A, 38B) arranged respectively on either side of the web and welded respectively to two of the respective profile edges of two corresponding hollow profiles. The manufacture of such a torsion box proves to be particularly simple, efficient, and inexpensive.