Aircraft Door Frame Joint Using Textured Metal-Thermoplastic Welding

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Solution Overview

Problem

Conventional aircraft door frame constructions are heavy and complex, requiring numerous mechanical fasteners that increase weight and reduce assembly efficiency, while also concentrating stress and compromising fatigue strength.

Innovation Solution

A method involving the use of a metal connecting component with textured surfaces for welding to fiber-reinforced thermoplastics materials, reducing the need for mechanical fasteners and enhancing stress distribution through areal connections, thereby improving weight reduction and assembly efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If metal angle pieces with mechanical fasteners (screws or rivets) are used to connect attachment struts to members and fuselage structure, then reliable mechanical connection is achieved, but weight increases and assembly complexity increases

Engineering Contradiction:

Improveconnection reliabilityVSAvoidframe weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The patent replaces the mechanical fastening system (screws or rivets through metal angle pieces) with a welding process. The attachment struts are welded directly to the frame members, eliminating the need for separate fasteners and metal angle pieces. This substitution reduces weight while maintaining connection reliability through the welded joint.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent merges multiple components (metal angle pieces and mechanical fasteners) into a single integrated welding process. The attachment struts are directly welded to the frame members, combining what were previously separate elements into one unified connection method, thereby reducing overall weight and simplifying the structure.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If metal angle pieces and mechanical fasteners are used for fastening attachment struts, then secure connection is achieved, but device complexity and assembly time increase

Engineering Contradiction:

Improvefastening securityVSAvoidassembly complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the complex mechanical fastening system involving metal angle pieces, screws, or rivets with a simpler welding process. The attachment struts are welded directly to the frame members, eliminating multiple components and assembly steps, thereby reducing device complexity while maintaining secure connection.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If mechanical fasteners (screws or rivets) are used to connect frame components, then assembly is achieved, but stress concentration occurs and fatigue strength is compromised

Engineering Contradiction:

Improveassembly capabilityVSAvoidfatigue strength

Core Design Contradiction:

ProductivityVSStrength

Solution Approach 1:

The patent replaces mechanical fasteners (screws or rivets) that create stress concentration points with a welding process. The welded connection distributes stress more evenly across the joint area between attachment struts and frame members, improving fatigue strength while maintaining assembly capability.

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 method results in a lighter, more robust door frame structure with reduced mechanical stress concentrations and improved fatigue strength, achieved through the use of metal connecting components welded to fiber-reinforced thermoplastics, which simplifies assembly and enhances the structural integrity of aircraft door frames.

Implementation Method 1

a first connecting zone is formed on a first assembly surface of a connecting component by generating a surface texture of the assembly surface... by melting of the metal material on the first and on the second assembly surface by a laser beam

Methodology Applied

Scientific EffectLaser heating: Laser

Implementation Method 2

the connecting component and the door frame member are welded, wherein thermoplastics material of the door frame member ingresses into the first connecting zone of the connecting component... thermoplastics material... is, in the region of the surface against which the first assembly surface of the connecting component bears, changed into a plastically deformable state

Methodology Applied

Scientific EffectThermal melting: Melting

Data Source

PatentUS11548659B2Method for producing a frame component for a door frame structure of an aircraft, frame component, and door frame structure

Publication Date: 2023.01.10 AIRBUS OPERATIONS GMBH

AI summary

A method for producing a frame component for a door frame structure of an aircraft. A connecting zone is generated on a first and a second assembly surface of a connecting component in each case by generating a surface texture on the assembly surfaces, wherein the connecting component is formed from a metal material. The assembly surfaces of the connecting component are placed against a door frame member and against an attachment member, wherein the door frame member and the attachment member are each formed from a fiber-reinforced thermoplastics material. Furthermore, the connecting component and the door frame member are welded, and the connecting component and the attachment member are welded. A frame component and a door frame structure are also described.