Stringer-less Composite Fuselage Structure Design

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Solution Overview

Problem

Traditional fuselage construction techniques optimized for metallic skins are not effective for composite materials, leading to suboptimal structural performance and increased complexity in manufacturing composite aircraft fuselage structures.

Innovation Solution

A stringer-less fuselage structure using a composite skin with integral tear straps and metallic frames, where the composite skin is closed in the circumferential direction and may have a non-cylindrical or conical shape, eliminating the need for traditional stringers and allowing for simplified manufacturing and reduced weight.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If traditional fuselage construction techniques with stringers are used for composite skins, then structural support is provided, but device complexity and manufacturing difficulty increase

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

Solution Approach 1:

The patent removes stringers from the fuselage structure, extracting the problematic intermediate component that caused complexity. The composite skin is designed to provide structural support independently through its inherent material properties and optimized geometry, eliminating the need for additional stringer elements while maintaining required strength and stiffness.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the structural support function directly into the composite skin itself, combining what were previously separate functions (skin covering and structural support via stringers) into a unified structure. The composite skin is engineered to bear loads and provide structural integrity without requiring separate support elements.

Inventive Principle:
Principle #5Merging (Combining)

2Strength

If traditional fuselage construction with stringers is used, then structural performance is achieved, but weight increases

Engineering Contradiction:
Improvestructural performanceVSAvoidfuselage weight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

By removing stringers from the structure, the patent eliminates the weight of these additional components. The composite skin, with its high strength-to-weight ratio, provides the necessary structural performance without the extra weight penalty associated with traditional metallic stringer assemblies.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent leverages the superior properties of composite materials, which offer higher strength-to-weight ratios compared to traditional metals. The composite skin can provide equivalent or superior structural performance to traditional constructions with stringers while significantly reducing overall weight.

Inventive Principle:
Principle #40Composite materials

3Ease of manufacture

If traditional fuselage construction techniques are used for composite materials, then manufacturing experience is utilized, but manufacturing efficiency decreases

Engineering Contradiction:
Improvemanufacturing experienceVSAvoidmanufacturing efficiency
Core Design Contradiction:
Ease of manufactureVSProductivity

Solution Approach 1:

The patent combines the skin and structural support functions into a single composite component, reducing the number of assembly steps. Instead of separately manufacturing and assembling stringers and skin panels, the integrated composite structure can be manufactured as a unified piece or with fewer joints, streamlining the manufacturing process.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The composite skin is designed with integrated features such as tear straps and reinforcement zones that are built-in during manufacturing rather than added separately. This segmentation of functions into the base structure eliminates subsequent assembly operations and reduces manufacturing complexity.

Inventive Principle:
Principle #1Segmentation

4Weight of moving object

If composite materials are used for fuselage skin, then weight is reduced, but structural optimization for traditional constructions is lost

Engineering Contradiction:
Improvefuselage weightVSAvoidstructural optimization
Core Design Contradiction:
Weight of moving objectVSStrength

Solution Approach 1:

The patent fully exploits the advantages of composite materials by designing a structure that leverages their anisotropic properties, high strength-to-weight ratio, and design flexibility. The composite skin is engineered with optimized fiber orientations and layer configurations to provide superior structural performance tailored to the specific load conditions.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent applies local quality by varying the composite material properties in different regions of the fuselage skin. Tear straps and reinforcement zones are strategically positioned and designed with different thicknesses and material compositions to address specific structural requirements, providing optimized performance where needed while maintaining weight efficiency elsewhere.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP3362355B1Stringer-less fuselage structure and method of manufacture
Publication Date: 2020.05.20 BOMBARDIER INC
  • EP3362355B1 patent drawingFigure 1
  • EP3362355B1 patent drawingFigure 2A
  • EP3362355B1 patent drawingFigure 2B

AI summary

Stringer-less fuselage structures and associated methods of manufacturing are disclosed. In some embodiments, a fuselage structure includes a composite fuselage skin (24) including a plurality of tear straps (32) formed in the composite fuselage skin where each tear strap extends generally along a longitudinal axis of the composite fuselage skin. The fuselage structure also includes a plurality of frames (28) supporting an interior of the composite fuselage skin where the frames are spaced apart along the longitudinal axis of the composite fuselage skin.