Aircraft Fuselage Connector for Rivet-Free Frame-Stringer Assembly

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Solution Overview

Problem

Existing aircraft fuselage structures face challenges in simplifying the assembly of frames and stringers, particularly in difficult-to-access intersection areas, and often require riveting or other complex fastening methods.

Innovation Solution

A connector with a coupling structure that engages around the cross-section of a stringer and a second connecting section that attaches to the frame, allowing for a positive connection without riveting, using hook-shaped or L-shaped configurations and optionally adhesive carriers for enhanced support and rigidity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional riveting methods are used to connect frames and stringers, then connection strength is ensured, but assembly complexity and time increase significantly

Engineering Contradiction:
Improveconnection strengthVSAvoidassembly efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent replaces the traditional riveting mechanical system with a snap-fit coupling mechanism. The coupling structure includes a coupling element that engages with a recess in the stringer and a corresponding engagement feature on the frame, allowing for tool-free or minimal-tool assembly while maintaining structural integrity through geometric interlocking rather than mechanical fastening.

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

Solution Approach 2:

The connector is divided into separate functional elements: a coupling structure for engaging the stringer, a connection structure for attaching to the frame, and optionally an adhesive support. This segmentation allows each component to be optimized independently and simplifies the assembly process by enabling modular installation.

Inventive Principle:
Principle #1Segmentation

2Strength

If complex fastening methods are used to ensure structural rigidity, then connection strength is improved, but device complexity increases

Engineering Contradiction:
Improvestructural rigidityVSAvoidconnector complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent merges multiple functions into a single integrated connector component. The coupling structure and connection structure are combined in one piece that simultaneously engages both the stringer and frame, eliminating the need for separate fasteners, alignment fixtures, or multiple assembly steps while maintaining structural rigidity through the unified geometry of the connector.

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If riveting is used in difficult-to-access intersection areas, then reliable connection is achieved, but ease of operation deteriorates

Engineering Contradiction:
Improveconnection reliabilityVSAvoidassembly ease
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The coupling structure is designed to be self-aligning and self-locating. The coupling element engages with the recess in the stringer and the engagement feature on the frame through automatic geometric guidance, eliminating the need for precise manual alignment or specialized tools required in difficult-to-access areas. The snap-fit mechanism provides inherent positioning that ensures reliable connection without operator skill dependency.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP3907129B1Connector and method for connecting a frame and a stringer of a fuselage structure of an aircraft, fuselage structure and aircraft
Publication Date: 2025.07.02 PREMIUM AEROTECH GMBH
  • EP3907129B1 patent drawingFigure 1~2
  • EP3907129B1 patent drawingFigure 3~5
  • EP3907129B1 patent drawingFigure 6~7

AI summary

A connector (1) for connecting a frame (110, 510) with a stringer (115, 120) extending transversely to it of a fuselage structure (100, 500) of an aircraft comprises a base support (2) extending in a longitudinal direction (L1) of the connector, a first connecting section (4) connected to the base support (2) and extending in a first transverse direction of the connector, which has a coupling structure (40, 5340, 534, 60) in an end region (62) facing away from the base support (2) for gripping an end region of a cross-section of the stringer (120), and a second connecting section (4, 6) connected to the base support (2), which is designed for connection with the frame (110).