Wind Turbine Spar Cap with Nested Root Insert
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Solution Overview
Problem
Wind turbine rotor blades face challenges in achieving sufficient stiffness, buckling resistance, and strength while minimizing weight and cost, particularly due to the need for thickened blade roots to absorb loads, which adds weight and expense.
Innovation Solution
The use of pre-cured composite members grouped into layers forming spar caps that separate into bundles and fit within root inserts, transferring loads directly to the inserts, and the integration of pultruded members to form lighter and more efficient spar caps with variable widths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the blade root is thickened to absorb loads from the spar cap, then the strength and load-bearing capacity are improved, but the weight and manufacturing cost increase
Solution Approach 1:
The spar cap member bundles are nested within the root insert, with the member bundles fitting inside the root insert's openings. This nested configuration allows load transfer from the spar cap to the root insert without requiring a thickened blade root, thereby maintaining strength while reducing weight.
Solution Approach 2:
The root insert acts as an intermediary component between the spar cap member bundles and the blade root. It provides a structured interface for load transfer, enabling efficient stress distribution without requiring excessive root thickness, thus resolving the contradiction between strength and weight.
2Ease of manufacture
If traditional spar caps are tapered and blended to a thin section near the blade root, then the manufacturing complexity is reduced, but the structural integrity and load transfer capability are compromised
Solution Approach 1:
The spar cap is segmented into multiple pre-cured composite members that are grouped into bundles. These segmented members can be manufactured independently with consistent cross-sections, simplifying production while maintaining structural integrity through the bundled configuration that effectively transfers loads to the root insert.
Solution Approach 2:
The invention uses pre-cured composite members with consistent cross-sections that are grouped into bundles. These composite members maintain structural integrity while being easier to manufacture than traditionally tapered spar caps, as they can be produced using standardized pultrusion or molding processes.
3Productivity
If pre-cured composite members are used to form spar caps, then the manufacturing time and assembly steps are reduced, but the structural continuity and load distribution may be affected
Solution Approach 1:
The composite members are pre-cured into bundles before assembly into the spar cap structure. This preliminary action allows for controlled manufacturing of individual bundles with consistent properties, which can then be quickly assembled into the final structure, maintaining both productivity and structural continuity through proper bonding or mechanical connection.
Data Source
AI summary
A rotor blade 16 of a wind turbine 10 having a pultruded spar cap 20 is disclosed. The rotor blade 16 includes a blade root 30 and a blade tip 32. The blade root 30 includes at least one root insert 33. The rotor blade 16 also includes at least one spar cap 20 constructed of a plurality of pultruded members 50 grouped together to form one or more layers 52 from the blade tip 30 towards the blade root 32. Further, the pultruded members 50 separate into one or more pultruded member bundles 54 as the spar cap 20 approaches the blade root 30. The pultruded member bundles 54 fit within the root insert 33, along with the blade bolts 44, such that compression and tension loads of the rotor blade 16 are transferred through the pultruded members 50.