Composite Duct Bracket Assembly for Flange Stress Relief

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Solution Overview

Problem

Composite ducts in gas turbine engines experience increased stress and interlaminar stresses at the intersection of the flange and body portion due to bending moments during operation, which can compromise the structural integrity and manufacturing complexity.

Innovation Solution

A bracket assembly is used to support the flange of a composite duct, featuring a first foot with flange fastener openings and a second foot with body portion fastener openings, along with load spreaders and spacers to distribute and transfer loads, reducing interlaminar stresses and manufacturing complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a composite duct is used in a gas turbine engine, then weight is reduced and corrosion resistance is improved, but interlaminar stresses increase at the flange-body intersection during operation

Engineering Contradiction:
Improvestructural integrityVSAvoidinterlaminar stresses
Core Design Contradiction:
StrengthVSStress or pressure

Solution Approach 1:

A bracket assembly is introduced as an intermediary component between the flange and the duct body. The bracket includes a first portion engaging the flange and a second portion engaging the duct body, with load spreaders positioned between them. This intermediary structure distributes and transfers loads away from the critical flange-body intersection, reducing interlaminar stresses in the composite duct while maintaining structural integrity.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of manufacture

If the flange and body portion are joined directly, then manufacturing complexity is reduced, but stress concentration occurs at the intersection

Engineering Contradiction:
Improvemanufacturing complexityVSAvoidstress distribution
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The connection structure is segmented into distinct components: the bracket assembly with its first portion, second portion, and load spreaders. This segmentation allows each component to be optimized independently for its specific function while collectively providing superior stress distribution compared to a direct joint, balancing manufacturing complexity with improved structural performance.

Inventive Principle:
Principle #1Segmentation

3Stress or pressure

If load spreaders are added to distribute loads, then interlaminar stresses are reduced, but device complexity increases

Engineering Contradiction:
Improveinterlaminar stressesVSAvoidbracket assembly complexity
Core Design Contradiction:
Stress or pressureVSDevice complexity

Solution Approach 1:

Multiple functional elements are merged into a single integrated bracket assembly. The first portion, second portion, and load spreaders are combined in one structure that can be manufactured as a single piece or pre-assembled unit. This merging approach reduces the number of separate components and assembly steps compared to using separate brackets and load spreaders, thereby limiting the increase in device complexity while maintaining effective load distribution.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP3760842B1Gas turbine engine composite duct with bracket
Publication Date: 2026.03.18 RTX CORP
  • EP3760842B1 patent drawingFigure 1
  • EP3760842B1 patent drawingFigure 2~4
  • EP3760842B1 patent drawingFigure 5

AI summary

A bracket (70) assembly for a gas turbine engine (20) includes a first foot (72) that includes at least one flange fastener opening (78) and a duct flange support surface (100). A second foot (74) includes at least one body portion fastener opening (84) and a duct body support surface (102). At least one leg (76) connects the first foot (72) relative to the second foot (74).