Structural Profile Joining by Thermal Expansion and Interference Fit

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Solution Overview

Problem

Current methods for joining structural profiles in aircraft and other applications require numerous mechanical fasteners and tools, leading to increased assembly effort and weight, and often struggle with manufacturing tolerances.

Innovation Solution

A method involving the expansion or contraction of structural profiles to achieve a form fit or interference fit without the need for mechanical fasteners, using thermal or mechanical deformation to align mating contours, allowing for assembly without physical contact or tools, and optionally using interface sealants or surface structures for enhanced load transfer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If mechanical fasteners and tools are used to join structural profiles, then the connection strength is ensured, but the assembly effort and weight increase

Engineering Contradiction:
Improveconnection strengthVSAvoidassembly complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent replaces mechanical fastening systems (screws, rivets, clamps) with a thermal field-based joining method. By heating the structural profiles to enable expansion and subsequent cooling for contraction, the invention eliminates the need for mechanical fasteners and assembly tools, thereby reducing device complexity while maintaining connection strength through controlled thermal deformation

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

Solution Approach 2:

The invention changes the temperature parameter of the structural profiles to alter their physical dimensions. By heating the profiles above a transition temperature, they expand and can be easily joined; upon cooling below the transition temperature, they contract to create a secure fit. This parameter change enables joining without mechanical fasteners, reducing assembly complexity

Inventive Principle:
Principle #35Parameter changes

2Reliability

If mechanical fasteners are used to join structural profiles, then the connection reliability is ensured, but the weight of the structure increases

Engineering Contradiction:
Improveconnection reliabilityVSAvoidstructure weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The patent substitutes mechanical fasteners with a thermal field-based joining method. By controlling the temperature of structural profiles to induce expansion and contraction, the invention achieves reliable connections without adding the weight of screws, rivets, brackets, and other mechanical fastening components, thereby reducing overall structure weight while maintaining connection reliability

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

3Manufacturing precision

If structural profiles are joined with tight tolerances using conventional methods, then the manufacturing precision is improved, but the assembly effort increases

Engineering Contradiction:
Improvemating contour precisionVSAvoidtooling complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The invention changes the temperature parameter of structural profiles to dynamically adjust their dimensions. By heating profiles above a transition temperature, they expand to accommodate slight variations in mating contours; upon cooling below the transition temperature, they contract to achieve precise fits. This thermal parameter control enables manufacturing precision without requiring complex alignment tools or procedures

Inventive Principle:
Principle #35Parameter changes

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 the need for mechanical fasteners and tools, simplifies the assembly process, and enhances the structural integrity of joined components by creating a secure fit that can be reinforced with additional clamping forces or adhesives, while minimizing weight and cost.

Implementation Method 1

changing a size of at least one of the structural profiles at least at the respective mating contour by expansion or contraction of the respective structural profile

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

reversing the size change of the respective structural profiles by contraction or expansion such that at least one of a form fit or an interference fit is formed

Methodology Applied
Scientific EffectThermal contraction: Thermal Contraction

Implementation Method 3

changing a size of at least one of the structural profiles at least at the respective mating contour by expansion or contraction of the respective structural profile

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP4129817A1Method for joining structural profiles
Publication Date: 2023.02.08 AIRBUS OPERATIONS GMBH
  • EP4129817A1 patent drawingFigure 1~2
  • EP4129817A1 patent drawingFigure 3~4
  • EP4129817A1 patent drawingFigure 5~8

AI summary

A method for joining structural profiles (1a, 1b), in particular curved or angular structural profiles of an aircraft, comprises forming a first structural profile (1a) with a first mating contour (2a) at a first opening end (3a) and a second structural profile (1b) with a second mating contour (2b) at a second opening end (3b), the first mating contour being complementary formed to the second mating contour; changing a size of at least one of the structural profiles (1a, 1b) at least at the respective mating contour by expansion or contraction of the respective structural profile; sliding both structural profiles into each other at their respective opening ends while changed in size such that the structural profiles overlap at the mating contours; and reversing the size change of the respective structural profiles by contraction or expansion such that at least one of a form fit or an interference fit is formed between the structural profiles at their mating contours.