Composite Fan Blade Connection Using Intermediary Metallic Interface
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Solution Overview
Problem
Existing fan blade connection systems for industrial fans with composite blades face issues of stress concentration, leading to periodic maintenance needs and increased weight with metallic connections, while threaded elements are unsuitable for composite materials.
Innovation Solution
A fan blade connection system using a fastener element in the blade root, such as a barrel nut or cross dowel, in conjunction with a tensioning member like a stud, which distributes stresses effectively without requiring complex structures or heavy machinery, and includes an intermediary interface to avoid direct contact between the composite blade and rotor hub.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a projected integral portion in composite material is used to connect the blade to the rotor hub, then the connection is simplified, but the connection presents undesired adaptation after some time of operation requiring periodic inspection and maintenance
Solution Approach 1:
The patent introduces a metallic projected portion as an intermediary element between the composite blade and the rotor hub. This metallic portion acts as a mediator that connects the composite blade to the metallic rotor hub, providing a reliable connection that does not adapt over time. The metallic material maintains its dimensional stability and connection properties throughout operation, eliminating the adaptation issues associated with purely composite connections.
2Strength
If metallic projected portions are used to distribute stresses throughout the composite blade root, then stress distribution is improved, but the connection becomes heavier and expensive
Solution Approach 1:
The patent applies local quality by using metallic material specifically for the projected portion that needs to distribute stresses, while the rest of the blade remains composite. This localized application of metallic material provides the necessary stress distribution capability only where required at the blade root connection area, rather than making the entire blade metallic. This approach achieves adequate stress distribution while minimizing overall weight and cost.
3Device complexity
If threaded elements are used to fasten composite blades, then the connection is simplified, but the composite materials have low strength against concentrated stresses making this unsuitable
Solution Approach 1:
The metallic projected portion serves as an intermediary that bridges the composite blade and the fastening mechanism. The threaded elements are installed in the metallic projected portion rather than directly in the composite blade. This intermediary structure allows the use of threaded fasteners while distributing the concentrated stresses through the metallic material, which has higher strength against concentrated stresses than composite materials alone.
4Reliability
If custom-made components are used for the connection system, then the connection is optimized for specific applications, but the manufacturing cost and complexity increase
Solution Approach 1:
The metallic projected portion is designed as a universal component that can be used across different fan applications. The standardized design allows for off-the-shelf manufacturing and assembly, eliminating the need for custom-made components for each specific application. This universal approach maintains reliable connection performance while significantly reducing manufacturing complexity and cost.
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 reduces weight, eliminates the need for custom-made components, and provides a secure, efficient, and cost-effective connection that is suitable for medium and large industrial ventilation and cooling applications, with improved stress distribution and reduced maintenance requirements.
Implementation Method 1
a fastener element arranged in the blade root and extending essentially transversally to the longitudinal axis of the blade, said fastener element being adapted for receiving one of the ends of at least one tensioning member
Data Source
AI summary
A fan blade connection system and method for connecting at least one composite blade (110) to a rotor hub (120), more particularly, for fans used in industrial ventilation and cooling applications. The invention aims to provide a better connection, mainly in regard to the stresses distribution. The preferred embodiments are directed to a system and method for connecting a composite blade (110) to a rotor hub (120) comprising a fastener element (130) arranged in the blade root (111) and extending transversally to the longitudinal axis of the blade (110), said fastener element (130) being adapted for receiving one of the ends of a tensioning member (140) in a longitudinal position in relation to said blade (110). The tensioning member (140) may have an intermediary interface (160) between the blade (110) and the rotor hub (120), fixed by the end of the tensioning member, or fixed by at least one fastener component, which passes through holes in the rotor hub and in the intermediary interface.