Pre-cured Rotor Blade Spar Caps with Variable Stiffness
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Solution Overview
Problem
Wind turbine rotor blades face challenges in achieving variable stiffness to conform to aerodynamic profiles while maintaining structural integrity, as pultruded composites are thick and inflexible, leading to manufacturing complexities and increased material handling difficulties.
Innovation Solution
The use of pre-cured members with a combination of high-stiffness fiber materials and low-stiffness materials, such as rubber or foam, arranged in layers to create rotor blade components like spar caps, which can be manufactured via pultrusion or belt-pressing processes, allowing for increased flexibility and conformability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If pultruded composites are used to increase stiffness and strength, then structural integrity is improved, but flexibility and conformability to aerodynamic profiles deteriorate
Solution Approach 1:
The spar cap is constructed with varying thicknesses in different sections, creating local quality variations. Thicker sections provide higher stiffness and strength where structural integrity is critical, while thinner sections provide flexibility and conformability where adaptability to aerodynamic profiles is needed. This resolves the contradiction by making different parts of the same component have different properties optimized for their specific functions.
Solution Approach 2:
The invention uses composite material construction with multiple layers of pultruded composite members arranged in specific configurations. By combining materials with different stiffness characteristics and using layered construction, the spar cap achieves both the structural integrity from high-stiffness materials and the flexibility needed for conformability through the overall composite structure design.
2Strength
If pultruded composites are used to increase stiffness, then buckling resistance is improved, but manufacturing complexity and material handling difficulties increase
Solution Approach 1:
The spar cap is divided into multiple discrete pultruded composite members or sections that can be manufactured separately using standard pultrusion processes. These segmented components are then assembled into the final spar cap structure, reducing manufacturing complexity at the component level while achieving the required buckling resistance through the collective structural arrangement of all segments.
Solution Approach 2:
Individual pultruded composite members are pre-manufactured with controlled stiffness properties before assembly into the final spar cap structure. This preliminary action allows each component to be optimized and quality-controlled separately, reducing overall manufacturing complexity and improving material handling during assembly while ensuring the required buckling resistance is achieved.
3Productivity
If thicker pultruded sections are used to lower unit cost, then material throughput is improved, but conformability to aerodynamic profiles deteriorates
Solution Approach 1:
The spar cap employs varying thicknesses of pultruded composite members in different sections, creating local quality variations. Thicker sections are used where high material throughput and cost efficiency are priorities, while thinner sections are used where conformability to aerodynamic profiles is critical, thus resolving the contradiction between productivity and shape adaptability.
Solution Approach 2:
The spar cap is segmented into multiple pultruded members with different thicknesses optimized for their specific locations. This segmentation allows thick sections to be produced efficiently via high-throughput pultrusion for cost effectiveness, while thin sections provide the necessary conformability, balancing productivity and shape requirements.
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 reduces manufacturing defects, lowers production costs, and enhances the ability of rotor blade components to conform to complex aerodynamic profiles, while maintaining structural integrity and reducing wrinkling and dis-bonding issues.
Implementation Method 1
the resin cures or undergoes polymerization through added heat or other curing methods
Implementation Method 2
at least one additional material having a second stiffness that increases flexibility of the pre-cured members
Data Source
AI summary
The present disclosure is directed to a rotor blade component for a wind turbine. The rotor blade component includes a plurality of pre-cured members arranged in one or more layers. Each of the pre-cured members is constructed of a plurality of fiber materials cured together via a resin material having a first stiffness and at least additional material having a second stiffness. Further, the second stiffness is lower than the first stiffness. As such, the additional low-stiffness material is cured within the resin material so as to increase flexibility of the pre-cured members.