Wind Turbine Blade Interlocking Joint Design
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Solution Overview
Problem
Existing sectional wind turbine blades face challenges in achieving sufficient joint strength and stiffness during assembly, particularly in transferring loads and moments across the joint, while also dealing with the complexity of manufacturing dentations in spar caps without fiber splitting.
Innovation Solution
The use of a connecting part with interleaved sheets and fiber-reinforced layers in the spar cap structure, where the dentations are formed in the connecting part rather than the spar cap, allows for effective load transfer across the blade joint without compromising the integrity of the spar cap structure, enabling easier manufacturing and assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If dentations are made in the spar caps to increase joint strength, then the structural strength of the joint is improved, but the risk of fiber splitting increases making manufacturing difficult
Solution Approach 1:
The invention divides the blade structure into separate components: a spar cap structure and a connecting part. The dentations are formed only in the connecting part, not in the spar cap structure itself. This segmentation allows the spar cap to maintain its structural integrity without fiber splitting, while the connecting part provides the necessary interlocking dentations for joint strength.
Solution Approach 2:
The invention extracts the dentation function from the spar cap structure and relocates it to a separate connecting part. This extraction allows the spar cap to focus on its primary structural function without the manufacturing complications of forming dentations, while the connecting part specifically provides the dentation interlocking mechanism.
2Quantity of substance
If wind turbine blades are manufactured in sections for transport, then transportation and logistics costs are reduced, but the joint strength and stiffness between sections becomes challenging to achieve
Solution Approach 1:
The blade is segmented into multiple sections that can be manufactured and transported separately. The connecting part with dentations is designed to join these sections together, providing sufficient joint strength while allowing each section to be smaller and more manageable for transportation.
Solution Approach 2:
The connecting part is constructed as a composite structure with fiber-reinforced layers interleaved with sheets. This composite construction provides both the necessary joint strength and stiffness while accommodating the dentation geometry needed for section joining.
3Power
If the blade size is increased to improve energy generation, then power output is improved, but production facilities and transport means must be increased leading to higher costs
Solution Approach 1:
Large blades are divided into smaller sections that can be manufactured using existing production facilities and transported using current infrastructure. The sections are joined using the connecting part with dentations, allowing the final assembled blade to achieve the required size for high power output without requiring proportionally larger manufacturing and transport capabilities.
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 approach enhances joint strength and stiffness, reduces manufacturing costs, and simplifies the handling of large blades by allowing for smaller, more manageable sections, facilitating easier transportation and assembly, while maintaining the structural integrity of the wind turbine blade.
Implementation Method 1
The layers of the spar cap may be made of e.g. pre-pregs or pultrusions. The pultrusions may be cured and then stacked on top of each other in the shell mould optionally together with layers of other types of material, and are then bonded by resin infusion.
Data Source
Figure 1~2
Figure 3~4
Figure 5A~7
AI summary
A wind turbine blade comprising at least two wind turbine blade sections connected in a blade connection joint, where each blade section at their connection end comprises a number of corresponding dentations arranged to interconnect across the blade connection joint. One of the blade sections comprises a spar cap structure and a connecting part with a first end joined to the spar cap structure and an opposite second end positioned at the blade section connection end and comprising a number of the dentations. The connecting part further comprises a number of sheets which are interleaved with the fibre-reinforced layers of the spar cap structure in an overlapping zone thereby joining the spar cap structure and the connecting part. The invention further relates to a method for preparing a wind turbine blade section as mentioned above. The invention also relates to a method of preparing a sheet for a connecting part with a number of dentations at one end, which method involves cutting and rolling a number of unidirectional prepreg sheets to form fingers, placing in an open mould the fingers next to each other and partially apart such as to form the dentations, closing the mould, and fully or partially curing the sheet.