Composite Lug Cluster Attachment for Load-Bearing Structural Tubes

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Solution Overview

Problem

Challenges exist in attaching composite materials to metal or other composite components due to differences in material characteristics, particularly in aircraft landing gear systems, where traditional methods like threading or drilling reduce the strength of composite materials.

Innovation Solution

A lug cluster design featuring a saddle with a planar floor member and an upper infill member, secured to a composite tube using a fiber filament wrapped along grooves, which is consolidated through resin transfer molding, allowing the lug cluster to bear loads in any direction and maintain the integrity of the composite tube.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If traditional attachment methods (threading or drilling) are used to attach lugs to composite tubes, then the lug can be securely attached, but the strength and structural integrity of the composite tube are reduced

Engineering Contradiction:

Improvestructural integrity of composite tubeVSAvoidattachment security

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent introduces a saddle as an intermediary component between the lug and the composite tube. The saddle distributes the attachment loads over a larger area of the tube surface, preventing stress concentration that would occur with direct threading or drilling. This intermediary structure allows secure lug attachment while preserving the composite tube's structural integrity by avoiding penetrating fasteners.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent employs composite materials in the construction of the saddle and surrounding structure, allowing for optimized load distribution and stress management. The composite construction enables the attachment assembly to work harmoniously with the composite tube, maintaining material compatibility and structural performance while achieving secure lug attachment.

Inventive Principle:

Principle #40Composite materials

2Strength

If metal tubes are used in aircraft landing gear systems, then high strength and complex geometries can be achieved, but the weight of the system increases

Engineering Contradiction:

Improvestrength of structural componentsVSAvoidweight of landing gear system

Core Design Contradiction:

StrengthVSWeight of moving object

Solution Approach 1:

The patent transitions from metallic materials to composite materials, fundamentally changing the material parameters of the structural components. This parameter change enables achieving the required strength and complex geometries while significantly reducing the weight of the landing gear system, as composite materials offer high strength-to-weight ratios.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent extensively uses composite materials for the tube, saddle, and surrounding structure. These composite components provide the necessary mechanical strength and can be molded into complex geometries required for landing gear applications, all while maintaining lightweight characteristics that metallic materials cannot achieve.

Inventive Principle:

Principle #40Composite materials

3Force

If a lug cluster is attached to a composite tube, then load-bearing capability is improved, but the risk of reducing composite tube integrity increases

Engineering Contradiction:

Improveload-bearing capabilityVSAvoidintegrity of composite tube

Core Design Contradiction:

ForceVSStrength

Solution Approach 1:

The patent segments the attachment system into distinct functional components: the lug, the saddle, and the composite tube. This segmentation allows each component to be optimized for its specific function while working together as an integrated system. The saddle acts as a load-distributing interface that protects the tube from concentrated stresses.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The saddle serves as a critical intermediary element that mediates between the lug and the composite tube. It receives loads from the lug and distributes them over a broader area of the tube, preventing stress concentration and potential damage to the composite structure. This intermediary function enables high load-bearing capability while preserving tube integrity.

Inventive Principle:

Principle #24Intermediary (Mediator)

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

This solution enables secure attachment of lug clusters to composite tubes, distributing loads effectively while preserving the lightweight benefits of composite materials, and preventing the reduction of structural integrity.

Implementation Method 1

a fiber filament wrapped along grooves, which is consolidated through resin transfer molding, allowing the lug cluster to bear loads in any direction

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 2

consolidated through resin transfer molding

Methodology Applied

Scientific EffectResin transfer molding:

Data Source

PatentUS11536306B2Attachment of composite lug to composite structural tube

Publication Date: 2022.12.27 GOODRICH CORP

AI summary

A landing gear system includes a composite tube. The composite tube comprises at least one of (i) a filament wound composite tube, (ii) a filament braided tube, and (iii) a composite tube of laid up filament. The landing gear system further comprises a first lug cluster mounted to the composite tube and a second lug cluster mounted to the composite tube. The first lug cluster and the second lug cluster are oriented at an angle to one another.