Interleaved Metal-Fiber Root Ring for Wind Turbine Blade Loads
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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 unsuitable use of adhesives and bolts that bear tensile and bending loads rather than shear loads.
Innovation Solution
A method of manufacturing a root ring for a wind turbine blade involves winding metal sheet material onto a mandrel to form a metal section, interleaving it with fibre sheet material to create a transition section, and connecting it to a fibre section, allowing for efficient load distribution and improved bonding through pre-impregnated or resin-infused fibre materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If adhesives are used to hold bushings in place, then the connection is simplified, but the reliability deteriorates because adhesives are not optimally suited for constantly varying tensile forces
Solution Approach 1:
The patent replaces the adhesive bonding system with a mechanical fastening system using steel bushings and bolts. The bushings are embedded in the composite root end and the bolts pass through the bushings to connect to the pitch bearing, creating a mechanical connection that can better handle varying tensile forces compared to adhesive bonding alone.
Solution Approach 2:
The patent uses a hybrid construction combining steel bushings embedded in fibre composite material. This composite approach allows the steel bushings to provide mechanical strength for load-bearing while the fibre composite provides structural integration, creating a more reliable connection than either material alone.
2Device complexity
If bolts are used to connect pitch bearing to blade, then the connection is mechanically simple, but the efficiency deteriorates because bolts bear tensile and bending loads rather than shear loads
Solution Approach 1:
The patent applies different structural qualities to different parts of the connection system. The steel bushings provide localized mechanical anchoring in the composite root end, while the bolts provide localized shear connection to the pitch bearing. This local differentiation optimizes each component for its specific function, improving overall connection efficiency.
3Reliability
If large safety factors are used in blade connection design, then the reliability is improved, but the device complexity and material usage increase resulting in over-engineering
Solution Approach 1:
The patent changes the fundamental parameters of the connection system by introducing steel bushings as an intermediate mechanical element. This parameter change allows for more efficient load transfer mechanisms that achieve the required reliability with optimized rather than excessive safety factors, reducing over-engineering.
4Ease of manufacture
If current connection methods are used, then the manufacturing is straightforward, but the blade length is limited due to insufficient load-bearing capacity
Solution Approach 1:
The patent employs a composite connection system combining steel bushings embedded in fibre composite material. This hybrid construction provides enhanced load-bearing capacity that enables longer blade lengths while maintaining manufacturing feasibility through established composite manufacturing processes.
Data Source
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.