Y-Shaped Composite Stringer for Aircraft Panel Buckling

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Solution Overview

Problem

Existing stringers in the aerospace industry, such as 'double T'-section and 'omega'-section stringers, have limited momentum of inertia, are prone to buckling and post-buckling, and exhibit poor torsional behavior, while also facing challenges in weight savings and cost reductions.

Innovation Solution

A Y-shaped composite material stringer is proposed, featuring a structural cross-section with a Y-shape, comprising two structural elements: an open triangular shape structure and a web, which increases the momentum of inertia and enhances structural efficiency, buckling resistance, and torsional behavior.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If traditional double T-section or omega-section stringers are used, then manufacturing is simpler, but momentum of inertia is limited and buckling resistance is poor

Engineering Contradiction:
Improvebuckling resistanceVSAvoidcross-section complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent applies asymmetry by transitioning from symmetric double T-section or omega-section stringers to an asymmetric Y-shaped cross-section. The Y-shape with its branching geometry provides superior moment of inertia and buckling resistance while maintaining manufacturing feasibility through composite material forming processes.

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The invention introduces a new dimensional configuration by adopting a Y-shaped cross-section that extends in multiple directions from a central web, rather than the traditional linear or symmetric configurations. This dimensional change optimizes the distribution of material to maximize moment of inertia and buckling resistance.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Strength

If traditional stringer sections are used, then structural simplicity is maintained, but torsional behavior is poor

Engineering Contradiction:
Improvetorsional resistanceVSAvoidstructural complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The asymmetric Y-shaped cross-section inherently provides superior torsional resistance compared to symmetric traditional sections. The branching geometry creates a more efficient torsional stiffness distribution, resisting twisting loads more effectively while maintaining structural integrity.

Inventive Principle:
Principle #4Asymmetry

3Strength

If more material is added to increase momentum of inertia, then buckling resistance improves, but weight increases

Engineering Contradiction:
Improvemoment of inertiaVSAvoidstringer weight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The invention optimizes the geometric parameters of the cross-section by adopting a Y-shape that maximizes moment of inertia per unit weight. The branching configuration distributes material more efficiently, achieving higher stiffness-to-weight ratio compared to traditional sections that would require more material to achieve the same structural performance.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The use of composite materials enables the Y-shaped stringer to achieve high moment of inertia with reduced weight. Composites provide high strength-to-weight and stiffness-to-weight ratios, allowing the optimized Y-geometry to deliver superior structural performance without the weight penalty of adding more material.

Inventive Principle:
Principle #40Composite materials

4Manufacturing precision

If high bending angles are used in manufacturing, then structural efficiency improves, but wrinkles appear during manufacturing

Engineering Contradiction:
Improvestructural efficiencyVSAvoidmanufacturing defects
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent optimizes the bending angle parameter during manufacturing to balance structural efficiency and defect prevention. By controlling the forming process parameters, the Y-shaped cross-section achieves high structural efficiency while minimizing wrinkles and manufacturing defects through optimized tooling and process parameters.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP4552971A1Y-shaped stringers made of composite material
Publication Date: 2025.05.14 AIRBUS OPERATIONS SL
  • EP4552971A1 patent drawingFigure 1~2
  • EP4552971A1 patent drawingFigure 3
  • EP4552971A1 patent drawingFigure 4~5

AI summary

A Y-shaped stringer (100) made of composite material for a panel (1010) of an aircraft, the Y-shaped stringer (100) comprising a stringer web (110) having a cross-section in a I-shape, first and second flanges (130a, 130b) configured to be connectable to the composite panel of the aircraft, an open triangular shape structure (120) comprising first and second lower vertices (120a, 120b) respectively joined to the first and second flanges (130a, 130b) and an upper vertex (120c) connected to a first end of the stringer web (110), wherein the open triangular shape structure (120) and the stringer web (110) form a cross-section in a Y-shape.