Composite Actuator Rod End Assembly Without Drilling or Threading

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Solution Overview

Problem

Conventional aircraft actuators made of metallic materials are heavy due to their complex geometries and high strength, which poses a challenge in reducing weight while maintaining structural integrity when coupling with composite materials.

Innovation Solution

A composite actuator piston tube made of lightweight polymer matrix composites, such as carbon fiber, with a flared end that engages a rod end assembly without threading or drilling, using an embedded nut and locking mechanism to secure components, ensuring structural integrity and reduced weight.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If metallic materials are used for actuator components, then strength and structural integrity are improved, but weight increases

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

Solution Approach 1:

The actuator rod tube is constructed from composite materials consisting of reinforcement fibers (such as carbon fiber, graphite fiber, or aramid fiber) embedded in a polymer matrix resin. This composite structure provides high strength-to-weight ratio, maintaining structural integrity while significantly reducing the weight compared to conventional metallic actuator components

Inventive Principle:
Principle #40Composite materials

2Strength

If threading or drilling is used to secure rod end assembly, then connection strength is improved, but composite material integrity deteriorates due to stress concentrations and fatigue

Engineering Contradiction:
Improveconnection strengthVSAvoidfatigue life of composite
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

An embedded nut is integrated within the composite actuator rod tube to serve as an intermediary component for securing the rod end assembly. This embedded nut provides a secure threaded connection point without requiring threads or holes to be drilled into the composite material itself, thereby maintaining composite integrity and avoiding stress concentration that would reduce fatigue life

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The embedded nut is combined with the composite rod tube structure during manufacturing, creating an integrated assembly where the nut is embedded within the composite material. This merging allows the metal nut to provide secure threading while the composite material maintains its continuous fiber structure and fatigue resistance

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP3076048B1Composite actuator rod end assembly
Publication Date: 2024.01.17 GOODRICH CORP
  • EP3076048B1 patent drawingFigure 1A~1B
  • EP3076048B1 patent drawingFigure 2~3A
  • EP3076048B1 patent drawingFigure 3B

AI summary

The present disclosure describes composite actuator piston rods and methods for making such rods. Composite actuator piston rods of the present disclosure may include a flared end 38 and an embedded nut44 positioned within the flared end. A rod end assembly 50 may be secured to the embedded nut. The rod end assembly may include a rod attachment end 54 with a threaded surface 55 configured to engage the embedded nut and a wedge 52 configured to compress a portion of the flared end. The rod end assembly may also include an external nut 51 proximate to the wedge and configured to exert a force against the wedge.