Composite Drive Shaft Ring Reinforcement Against Torsional Buckling

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Solution Overview

Problem

Composite drive shafts made of thermoplastic matrix with embedded fibers are prone to local instability (buckling) under torsional stresses due to their thin-walled structure, which can lead to deformation and reduced performance.

Innovation Solution

Incorporating radially positioned ring members with high bending stiffness, either fully or partially around the tubular member, to resist buckling deformation, combined with automated fiber placement or tape laying methods for fabrication, which can enhance the structural integrity and adherence of the ring members.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If composite drive shafts are made with thin-walled structure to utilize strength efficiency per weight, then weight is reduced, but local instability (buckling) occurs under torsional stresses

Engineering Contradiction:

Improveweight of drive shaftVSAvoidlocal instability (buckling)

Core Design Contradiction:

Weight of moving objectVSStability of the object's composition

Solution Approach 1:

The drive shaft is segmented into multiple sections by inserting ring members at specific locations along the tubular composite shaft. These ring members divide the continuous thin-walled structure into shorter segments, reducing the effective length susceptible to buckling while maintaining the overall lightweight composite construction

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention combines different materials to create a composite structure: a lightweight tubular composite shaft made of thermoplastic matrix with embedded fibers, reinforced with ring members made of metal or composite materials. This hybrid composite structure provides both weight efficiency and buckling resistance

Inventive Principle:

Principle #40Composite materials

2Stability of the object's composition

If ring members are added to prevent buckling, then stability is improved, but device complexity increases

Engineering Contradiction:

Improveresistance to buckling deformationVSAvoidstructural complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

Instead of uniformly thickening the entire shaft wall, ring members are strategically positioned at specific locations along the shaft where buckling is most likely to occur. This localized reinforcement provides necessary stability while minimizing additional complexity and weight

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The ring members are designed and positioned in advance during the manufacturing process to preemptively prevent buckling deformation before it occurs under service loads. The automated fiber placement method allows for precise pre-positioning of rings during shaft fabrication

Inventive Principle:

Principle #10Preliminary action

3Manufacturing precision

If automated fiber placement is used for fabrication, then manufacturing precision is improved, but ease of manufacture decreases due to process complexity

Engineering Contradiction:

Improveprecision of fiber placementVSAvoidease of fabrication

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The invention utilizes parameters of the thermoplastic matrix material (melting point, flow characteristics) to enable automated fiber placement processing. The thermoplastic material can be heated to a molten state during fabrication, allowing for precise fiber placement and automated manufacturing while maintaining ease of production

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11859665B2Drive shafts made of composite materials and methods of making such shafts

Publication Date: 2024.01.02 HAMILTON SUNDSTRAND CORP

AI summary

A drive shaft has a tubular member extending between axial ends and being hollow. The tubular member is formed of a thermoplastic matrix with embedded fibers. At least one ring member is positioned radially of the tubular member. A method is also disclosed.