Wind Turbine Blade Shear Web Channel Structure
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Solution Overview
Problem
Conventional wind turbine blade configurations face challenges in achieving a strong and efficient bond between the shear web and spar caps, often resulting in excess bond paste, weight issues, and unpredictable bond strength due to air voids and squeeze-out, particularly problematic in sections where repair is not possible.
Innovation Solution
A channel structure with rigid side walls is affixed to the spar cap, allowing bond paste to be disposed between the channel and shear web, creating a longer effective bond length and controlling paste distribution to reduce stress concentrations, thereby enhancing bond strength and minimizing excess material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a rigid flange is used to achieve the desired bond width, then the bond width is sufficient, but the shear web length variance cannot be accommodated and excess bond paste is used
Solution Approach 1:
The flange is designed with a contoured lower surface that provides varying bond paste thickness in different regions. The contour includes a first region with greater thickness and a second region with lesser thickness, allowing the flange to accommodate variations in shear web length while maintaining adequate bond width through the adaptive thickness distribution.
Solution Approach 2:
The invention changes the geometric parameters of the flange by creating a contoured lower surface with non-uniform thickness distribution. This parameter variation allows the same flange structure to adapt to different shear web lengths, resolving the contradiction between maintaining precise bond width and accommodating length variances.
2Manufacturing precision
If excess bond paste is used to make up for length deviation, then the bond width is achieved, but unnecessary weight is added and paste may break off causing blade rattling
Solution Approach 1:
The flange employs local quality variation through its contoured lower surface, which provides different bond paste thicknesses in different regions. The first region has greater thickness while the second region has lesser thickness, allowing optimized paste distribution that achieves adequate bond width without unnecessary excess paste, thereby reducing blade weight.
Solution Approach 2:
Instead of uniformly applying excess bond paste across the entire flange, the invention applies partial excess action only in the first region where greater thickness is needed, while the second region uses lesser thickness. This partial application of excess paste achieves the required bond width without the penalty of unnecessary weight throughout the entire structure.
3Ease of manufacture
If bond paste is allowed to squeeze out freely, then the bonding process is simple, but air voids and unpredictable squeeze-out result in decreased bond strength
Solution Approach 1:
The flange acts as an intermediary element between the spar cap and the shear web. Its contoured lower surface controls the bond paste flow and distribution, mediating the bonding process to eliminate air voids and ensure predictable paste squeeze-out, thereby achieving both ease of manufacture and high bond strength.
Solution Approach 2:
The flange's contoured geometry is designed in advance to pre-determine the bond paste distribution pattern. This preliminary action of shaping the flange surface ensures that when bond paste is applied, it automatically distributes itself correctly, eliminating air voids and controlling squeeze-out before the bonding process even begins, thus maintaining both simplicity and strength.
4Ease of manufacture
If the bond paste thickness is not controlled, then the application process is simple, but stress concentrations occur reducing bond reliability
Solution Approach 1:
The contoured lower surface of the flange implements local quality control by providing different bond paste thicknesses in different regions. The first region has greater thickness while the second region has lesser thickness, which controls stress distribution and prevents stress concentrations, thereby enhancing bond reliability without complicating the application process.
Solution Approach 2:
The flange's contoured geometry enables self-service control of bond paste thickness. When bond paste is applied to the flange, the contour automatically regulates the paste thickness distribution, with the first region naturally receiving greater thickness and the second region receiving lesser thickness. This self-regulating mechanism ensures reliable stress distribution without requiring complex external control systems.
Data Source
AI summary
A wind turbine blade has upper and lower shell members with a respective spar cap configured on an internal face of the shell members. A shear web extends between the spar caps along a longitudinal length of the blade. A connection assembly is configured between the transverse ends of the shear web and the spar caps and includes a channel structure configured on the spar cap. The channel structure includes rigid side walls that extend from the spar cap along the longitudinal sides of the shear web. Bond paste is disposed between the channel structure side walls and the longitudinal sides of the shear web.