Pre-Impregnated Fibre Sheet for Wind Turbine Blade Bonding

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Solution Overview

Problem

Challenges in ensuring strong adhesion between the spar cap and the blade shell members in wind turbine blades, particularly when using different types of resins, and the complexity of applying primers on pre-manufactured spar caps without damaging them during handling.

Innovation Solution

Using a pre-impregnated fibre sheet with a first layer containing an adhesion promoter and a second layer for adherence to the spar cap and remaining blade shell parts, respectively, which facilitates resin infusion and reduces the need for primer application, thereby enhancing structural integrity and manufacturing efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a primer is applied to the spar cap to improve adhesion, then adhesion between the spar cap and blade shell members is improved, but the manufacturing process becomes more complex and time-consuming

Engineering Contradiction:
Improveadhesion between spar cap and blade shell membersVSAvoidcomplexity of primer application process
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent applies a primer layer to the spar cap surfaces before assembling the blade components. This preliminary action ensures that the adhesion promoter is already in place on the spar cap, allowing for immediate bonding when the blade shell members are assembled, thereby improving adhesion without adding complexity to the overall manufacturing process

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The primer acts as an intermediary substance between the spar cap and the blade shell members. It contains adhesion promoters that chemically or physically bond to both surfaces, creating a strong interface that bridges the two different materials and ensures durable attachment

Inventive Principle:
Principle #24Intermediary (Mediator)

2Strength

If primer is applied to pre-manufactured spar caps, then adhesion is improved, but damage to the primered surfaces occurs during lifting and handling

Engineering Contradiction:
Improveadhesion between spar cap and blade shell membersVSAvoidintegrity of primed surfaces during handling
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The primer is applied to the spar cap surfaces before the spar caps are lifted and handled during assembly. By having the primer already in place on protected surfaces, the need for re-application after handling is eliminated, and care can be taken to protect the primed surfaces during the lifting operation

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent anticipates potential damage to primed surfaces by applying the primer in advance and implementing careful handling procedures during lifting. This beforehand cushioning approach prevents the need for re-priming and ensures that the adhesion-promoting surfaces remain intact throughout the assembly process

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Adaptability or versatility

If different types of resins are used for spar cap and blade shell, then manufacturing flexibility is improved, but adhesion between components deteriorates

Engineering Contradiction:
Improveflexibility in resin selectionVSAvoidadhesion between spar cap and blade shell members
Core Design Contradiction:
Adaptability or versatilityVSStrength

Solution Approach 1:

The primer serves as an intermediary that bridges incompatible resin systems. It contains adhesion promoters that can bond to both the spar cap resin and the blade shell resin, allowing different resin types to be used while maintaining strong interfacial adhesion

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies the chemical parameters of the interface by introducing a primer layer with specific adhesion-promoting properties. This changes the surface chemistry at the interface between different resin systems, enabling compatibility and strong bonding despite the use of different resin types

Inventive Principle:
Principle #35Parameter changes

4Quantity of substance

If polyester resin is used instead of vinyl ester or epoxy resin, then cost is reduced, but adhesion properties deteriorate

Engineering Contradiction:
Improvecost of resin materialsVSAvoidadhesion properties of resin
Core Design Contradiction:
Quantity of substanceVSStrength

Solution Approach 1:

The primer acts as a mediator that enables polyester resin to achieve adhesion properties comparable to vinyl ester or epoxy resins. The adhesion promoters in the primer create strong bonds at the interface, compensating for the inherently lower adhesion properties of polyester resin

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the surface energy and chemical composition parameters of the spar cap interface through primer application. This modification allows polyester resin to adhere effectively to the spar cap, achieving the desired adhesion strength at lower material cost

Inventive Principle:
Principle #35Parameter changes

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 pre-impregnated fibre sheet improves adhesion and fracture toughness, reducing manufacturing time and costs by eliminating the need for primer application and minimizing damage during handling, while maintaining structural integrity even with resin type variations.

Implementation Method 1

the first fibre layer is pre-impregnated with an adhesion promoter

Methodology Applied
Scientific EffectAdhesion: Adhesive

Data Source

PatentEP4049835B1Method of manufacturing a wind turbine blade and a pre-impregnated sheet therefor.
Publication Date: 2026.04.01 LM WIND POWER AS
  • EP4049835B1 patent drawingFigure 1
  • EP4049835B1 patent drawingFigure 2A~2B
  • EP4049835B1 patent drawingFigure 3A~3C

AI summary

The present invention relates to a pre-impregnated fibre sheet (20a,20b) extending in a longitudinal direction and in a transverse direction and comprising a first fibre layer (21) forming part of an upper surface of the pre-impregnated fibre sheet and a second fibre layer (22) forming part of a lower surface of the pre-impregnated fibre sheet, wherein the first fibre layer is pre-impregnated with an adhesion promotor. The present invention further relates to methods of manufacturing a blade shell member or wind turbine blade comprising a pre-manufactured spar cap (100) and a number of pre-impregnated fibre sheets (20a,20b) arranged to obtain an improved adherence between the blade shell (80) and pre-manufactured spar cap, particularly when the pre-manufactured spar cap is resin infused with vinyl ester or epoxy resin and the blade mould is resin infused with polyester.