Thermoplastic Composite Drive Shafts With Ring Buckling Restraint

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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, along with the use of automated fiber placement or tape laying methods for fabrication, and optional wraps to enhance adherence and stability.

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 introducing ring members at spaced intervals along its length. These rings divide the continuous thin-walled structure into discrete segments, preventing buckling from propagating along the entire shaft while maintaining the overall lightweight composite construction.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Ring members with locally increased stiffness are strategically positioned at specific locations along the drive shaft where buckling is most likely to occur. This local reinforcement provides targeted stability support without requiring the entire shaft to be thick-walled, thus maintaining weight efficiency while preventing local instability.

Inventive Principle:

Principle #3Local quality

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:

The ring members are constructed using the same composite material system as the drive shaft itself, creating a unified composite structure. This integration reduces manufacturing complexity compared to attaching different materials, and allows the rings to be fabricated using the same automated fiber placement or winding processes already employed for the shaft.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentEP3809003A1Drive shafts made of composite materials and methods of making such shafts

Publication Date: 2021.04.21 HAMILTON SUNDSTRAND CORP

Figure 1
Figure 2A~2B
Figure 3A~3F

AI summary

A drive shaft has a tubular member (32) extending between axial ends and being hollow. The tubular member is formed of a thermoplastic matrix with embedded fibers. At least one ring member (34) is positioned radially of the tubular member. A method is also disclosed.