Composite Tube Yoke Bonding for Lighter Propeller Shafts

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Solution Overview

Problem

Existing propeller shafts are heavy due to forged steel joints and sheet steel tubes, leading to increased oscillation and reduced fatigue life due to welding-induced stress and corrosion issues, with limited operating angles for composite tube yokes.

Innovation Solution

A composite tube yoke made of pre-preg material with a yoke extension at one end and a tubular extension at the other, attached to the propeller shaft tube by bonding or tight fitting, allowing for lighter weight without strength reduction and improved operational angles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If steel materials and welding processes are used to assemble propeller shaft components, then structural strength is ensured, but the weight increases and fatigue life decreases due to welding-induced stress and heat affected zone

Engineering Contradiction:

Improvejoint strengthVSAvoidpropeller shaft weight

Core Design Contradiction:

StrengthVSWeight of moving object

Solution Approach 1:

The patent replaces traditional steel materials with composite materials (fiber-reinforced plastics) for the propeller shaft components. This substitution maintains the required structural strength while significantly reducing the weight of the propeller shaft assembly, directly resolving the contradiction between strength and weight.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent replaces the welding process with adhesive bonding to join components. This substitution eliminates the heat affected zone and welding-induced stress that reduce fatigue life, while also avoiding the weight penalty of traditional steel welding assemblies. The adhesive bonding process maintains joint strength without the harmful thermal effects.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If welding process is used to join propeller shaft components, then structural integrity is achieved, but fatigue life reduces due to heat affected zone and welding-induced stress

Engineering Contradiction:

Improvestructural integrityVSAvoidfatigue life

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The patent replaces the welding process with adhesive bonding. This substitution eliminates the heat affected zone and welding-induced stress concentration that compromise fatigue life, while maintaining structural integrity through the adhesive joint. The bonding process creates a stress-distributing connection without thermal damage.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of manufacture

If composite tube and tube yoke are formed as a single piece by filament winding, then manufacturing is simplified, but fiber orientation angles relative to pin positions reduce material strength

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidmaterial strength

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent divides the propeller shaft into separate components (tube and yoke) that are manufactured independently with optimized fiber orientations, then joins them through adhesive bonding. This segmentation allows each component to have its fibers oriented optimally for its specific stress conditions, maintaining material strength while still achieving simplified manufacturing compared to complex monolithic structures.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies different fiber orientation patterns to different regions of the composite components based on local stress requirements. By tailoring the fiber orientation to the specific functional demands of each component region, the design maintains maximum material strength while preserving manufacturing simplicity.

Inventive Principle:

Principle #3Local quality

4Weight of moving object

If aluminum material is used instead of steel for lightening, then weight is reduced, but thermal effects from welding further reduce strength and cause warping

Engineering Contradiction:

Improvepropeller shaft weightVSAvoidaluminum part strength

Core Design Contradiction:

Weight of moving objectVSStrength

Solution Approach 1:

The patent uses composite materials instead of aluminum, achieving weight reduction while avoiding the thermal sensitivity issues of aluminum welding. Composites can be joined by adhesive bonding without thermal damage, preserving strength while achieving the desired weight reduction.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent replaces welding with adhesive bonding for joining components. This eliminates the thermal effects that cause warping and strength reduction in aluminum, while maintaining the weight benefits of lightweight materials.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS12319136B2Carbon composite tube yoke

Publication Date: 2025.06.03 TIRSAN KARDAN SANAYI & TICARET ANONIM SIRKETI

AI summary

A tube yoke used in a propeller shaft, which provides power transmission in vehicles. The tube yoke has a body made of composite pre-preg material, which has an extension surface in the form of a yoke on one end and in the form of a tube on the other end, which is attached to the propeller shaft tube by bonding or tight fitting.