Hybrid Root Ring Structure for Wind Turbine Blade Load Transfer
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Solution Overview
Problem
Current methods for connecting wind turbine blades to the pitch bearing result in over-engineering and inefficient load distribution, limiting the ability to increase blade length and extract more energy from the wind due to the unsuitability of adhesives and bolts for tensile and bending loads, and the need for excessive glass fibre composite to distribute loads around the root end.
Innovation Solution
A method of manufacturing a root ring for a wind turbine blade involving winding metal and fibre sheet materials onto a mandrel, interleaving them to form a transition section, and connecting the root ring to the blade shell, allowing for efficient load distribution and improved bonding between materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If adhesive is used to hold bushings in place, then the connection is simple to implement, but the adhesive is subject to constantly varying tensile forces which it is not optimally suited for, reducing reliability
Solution Approach 1:
The patent replaces the adhesive bonding system with a mechanical fastening system using bolts and bushings. The bushings are inserted into the blade root and secured with bolts, transitioning from a chemical bonding mechanism (adhesive) to a mechanical one that can better handle the varying tensile forces and loads experienced during blade operation.
2Strength
If bolts are used to connect pitch bearing to blade, then the connection can bear tensile and bending loads, but the bolts bear tensile and bending loads rather than shear loads to which they are better suited, reducing efficiency
Solution Approach 1:
The patent introduces bushings as intermediary components between the bolts and the blade root. These bushings are embedded in the blade root and provide bearing surfaces that allow the bolts to connect the pitch bearing to the blade. The bushings enable the connection to bear tensile and bending loads while the bolts primarily experience shear loads, which is their optimal loading condition.
3Strength
If large amount of glass fibre composite is used to spread loads around root end, then load distribution is improved, but the component parts are not used in an optimal way resulting in over engineering
Solution Approach 1:
The patent segments the load-bearing function across multiple components: the glass fibre composite root structure, the metal bushings, and the bolts. Instead of relying solely on excessive composite material to distribute loads, the load path is divided and optimized across these separate elements, each performing its specific function efficiently.
Solution Approach 2:
The patent employs a composite construction combining glass fibre composite for the root structure with metal bushings and bolts for the connection mechanism. This multi-material approach allows each material to be used where it is most effective: the composite provides structural integrity and load distribution, while the metal components provide precise load transfer paths and mechanical fastening.
4Ease of manufacture
If current blade/hub connection method is used, then the connection is simple to implement, but the method limits the extent to which blade length can be increased
Solution Approach 1:
The patent changes the fundamental parameters of the blade-hub connection system by transitioning from adhesive bonding to a mechanical bolt-and-bushing system. This parameter change enables the connection to handle the increased loads and stresses associated with longer, heavier blades, thereby allowing blade length to be increased while maintaining connection reliability.
Data Source
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AI summary
A method of manufacturing a root ring for a wind turbine blade comprising winding metal sheet material onto a mandrel to form a metal section proximate a hub end of the root ring. Sheet fibre material is also wound onto the mandrel to form a fibre section of the root ring proximate a tipwards end of the root ring. The metal sheet material is interleaved with the sheet fibre material to form a transition section of the root ring between the metal section and the fibre section.