Wind Turbine Blade Prepreg Layup with Cured Resin Layers
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Solution Overview
Problem
The manufacturing of wind turbine blades using resin-preimpregnated fibres, or prepregs, faces challenges such as shape retention issues leading to wrinkles, limited sidewise stability causing fibre misalignment, and exothermic curing resulting in thermal stresses and material degradation, especially for large thicknesses.
Innovation Solution
A method involving the pre-assembly of layers with cured fibre reinforced resin and uncured resin-preimpregnated fibres in an overlaying relationship, which eases handling and alignment, suppresses wrinkle formation, and reduces thermal stresses by embedding cured layers to absorb heat, thereby maintaining lower average temperature increases during curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If layers of resin-preimpregnated fibres (prepregs) are arranged on a moulding surface and subjected to vacuum and heat for curing, then the blade structure is formed, but the exothermic curing process results in high thermal stresses and material degradation
Solution Approach 1:
The blade structure is divided into alternating layers of cured and uncured fibre reinforced resin. The cured layers act as thermal barriers that segment the heat generation from the exothermic curing process, preventing excessive temperature buildup while maintaining structural integrity.
Solution Approach 2:
Some layers of fibre reinforced resin are pre-cured before assembly, while others remain uncured. This preliminary curing action creates a layered structure where cured layers provide thermal management during the subsequent curing of remaining uncured layers, reducing overall thermal stress.
2Ease of manufacture
If prepregs are delivered rolled-up and laid out on the moulding surface, then the manufacturing process is simplified, but shape retention issues cause wrinkles in the fibres
Solution Approach 1:
Layers of fibre reinforced resin are pre-cured in a flat configuration before assembly. This preliminary action establishes proper shape and prevents wrinkles from forming during the lay-up process, as the cured layers maintain their flat geometry when stacked with uncured layers.
Solution Approach 2:
The structure combines cured and uncured fibre reinforced resin layers. The cured layers provide dimensional stability and prevent wrinkling, while the uncured layers remain pliable for easy handling and conforming to the moulding surface.
3Volume of moving object
If large sized prepregs are cut and moved to the moulding surface, then the blade components are formed, but the limited sidewise stability causes misalignment of fibres
Solution Approach 1:
Fibre reinforced resin layers are pre-cured in their final configuration before assembly into the blade. This preliminary curing ensures that large components maintain their alignment and shape during handling and transport to the moulding surface, eliminating misalignment issues.
4Volume of moving object
If multiple layers of uncured prepregs are stacked for large thickness, then the blade structure is achieved, but handling becomes difficult and wrinkles worsen in upper layers
Solution Approach 1:
The thick blade structure is segmented into alternating layers of cured and uncured fibre reinforced resin. The cured layers provide structural rigidity and ease of handling, while the uncured layers remain flexible for stacking and conforming, preventing wrinkles from propagating through thick sections.
Solution Approach 2:
The blade combines cured and uncured composite materials in alternating layers. This composite structure provides the mechanical strength and handling ease of cured materials while maintaining the formability and flexibility of uncured materials, enabling efficient manufacturing of thick blade sections.
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 method enhances fibre alignment, reduces material handling difficulties, minimizes thermal stresses, and prevents material degradation, resulting in improved mechanical properties and easier processing of large wind turbine blade components.
Implementation Method 1
reduces thermal stresses by embedding cured layers to absorb heat, thereby maintaining lower average temperature increases during curing
Implementation Method 2
the curing is an exothermic process and therefore may result in disadvantageous built-in thermal stresses and deformations
Data Source
AI summary
The present invention relates to a method of manufacturing a wind turbine blade or a part of a wind turbine blade. The method comprises arranging at least one of layer of uncured resin pre-impregnated fibres, called prepregs, and at least one layer of cured fibre reinforced resin in an at least partly overlaying relationship, and curing the resin of the at least one layer comprising uncured resin. The at least one layer of cured fibre reinforced resin is assembled with at least one layer of uncured resin-preimpregnated fibres prior to being placed on a moulding surface. The method may e.g. be used to manufacture a wind turbine blade shell member or a wind turbine blade spar member. The invention further relates to a wind turbine blade shell member or a wind turbine blade spar member manufactured by such a method. The invention further relates to a pre-form for use in a wind turbine blade, the pre-form comprising at least one of layer of uncured resin pre-impregnated fibres and at least one layer of cured fibre reinforced resin in an at least partly overlaying relationship.