Wind Turbine Blade Spar Cap Infusion Promoting Layer
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Solution Overview
Problem
The resin infusion process in wind turbine blade manufacturing often results in airlocks and uneven resin flow, leading to voids and structural integrity issues due to the difficulty in matching infusion speeds through the blade layup, particularly around the spar caps.
Innovation Solution
Incorporating a fibre-reinforced polymer stack structure with an infusion promoting layer, such as a twisted yarn fabric, to ensure consistent resin infusion speed and prevent voids by acting as a medium that facilitates even resin distribution between the strips, thereby enhancing the structural integrity of the blade.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a stack of pultruded CFRP strips is used to form spar caps, then the blade achieves high strength and stiffness, but resin infusion becomes difficult with airlocks and uneven flow
Solution Approach 1:
A resin infusion promoting layer is introduced as an intermediary between the pultruded CFRP strips. This layer has higher resin permeability than the CFRP strips themselves, acting as a mediator that facilitates resin flow through the stack structure. The promoting layer prevents air entrapment and ensures uniform resin distribution, resolving the contradiction between maintaining high strength CFRP construction and achieving quality resin infusion.
Solution Approach 2:
The resin infusion promoting layer is designed with porous characteristics and higher permeability compared to the dense CFRP strips. This porous structure allows resin to flow more easily through the promoting layer, preventing airlocks and ensuring complete impregnation of the CFRP strips while maintaining the structural integrity and strength of the spar cap.
2Strength
If multiple CFRP strips are stacked to achieve required thickness, then structural capacity increases, but resin flow matching becomes difficult
Solution Approach 1:
The resin infusion promoting layer serves as a mediator between the resin source and the multiple CFRP strips. By positioning this high-permeability layer between adjacent strips, it creates controlled flow paths that balance resin distribution across all strips simultaneously, enabling uniform infusion speed throughout the stack while maintaining the required structural capacity through multiple strips.
Solution Approach 2:
Different regions of the spar cap construction are assigned different permeability qualities: the CFRP strips have low permeability to maintain structural density and strength, while the interleaved promoting layers have high permeability to facilitate resin flow. This local differentiation of material properties enables both high load bearing capacity and controlled resin infusion speed matching.
3Reliability
If resin infusion speed varies around spar caps, then manufacturing complexity increases, but blade structural integrity is compromised
Solution Approach 1:
The resin infusion promoting layer is distributed uniformly between all adjacent CFRP strips throughout the spar cap structure. This homogeneous arrangement creates consistent flow resistance and infusion speed across the entire stack, eliminating localized variations that would compromise structural integrity. The uniform distribution simplifies the infusion process by creating predictable, even resin flow throughout the blade.
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
The use of twisted yarn fabrics in the infusion promoting layer improves resin infusion speed and distribution, reducing the risk of voids and ensuring a more consistent and robust blade structure, matching infusion speeds with surrounding blade components.
Implementation Method 1
at least one adjacent pair of the plurality of strips including an infusion promoting layer interleaved therebetween, and wherein the or each infusion promoting layer is a fabric comprising a plurality of twisted yarns
Data Source
AI summary
A wind turbine blade including an elongate reinforcing structure, the reinforcing structure comprising a plurality of strips of fibre-reinforced polymer arranged into a stack structure, and at least one adjacent pair of the plurality of strips including an infusion promoting layer, wherein the infusion promoting layer is a fabric comprising a plurality of twisted yarns. The invention is also expressed as a method of assembling a wind turbine blade.