Wind Turbine Spar Cap Cavity for Shear Web Bonding

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Solution Overview

Problem

Conventional wind turbine blade assembly processes face challenges in achieving a secure bond between shear webs and spar caps due to difficulties in achieving precise dimensions and sufficient surface area, leading to issues like breakage, misalignment, and reduced bond strength, especially in inaccessible sections.

Innovation Solution

The design incorporates a cavity structure within the spar caps to accommodate the shear web, allowing for adjustable bond width and thickness through the use of a bonding material, which can accommodate length variances and improve the bond strength by distributing stress uniformly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional shear web assembly methods are used, then the assembly process is simple, but the bond strength and reliability are insufficient due to difficulty in achieving precise dimensions and adequate bond surface area

Engineering Contradiction:
Improvebond reliabilityVSAvoidassembly complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The spar cap is pre-formed with a cavity structure that accommodates the shear web before assembly. This preliminary preparation ensures proper positioning and bond surface area without requiring complex adjustment procedures during assembly, thereby improving bond reliability while keeping the assembly process simple.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The shear web is positioned within the cavity structure of the spar cap, creating a nested configuration. This nesting approach ensures adequate bond surface area and proper alignment while simplifying the assembly process, as the shear web naturally fits within the pre-formed cavity without requiring complex positioning procedures.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Manufacturing precision

If exact length dimensions are required for the shear web, then the bond accuracy is improved, but the manufacturing and assembly process becomes more difficult and time-consuming

Engineering Contradiction:
Improvedimensional accuracyVSAvoidassembly ease
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The cavity structure in the spar cap provides a standardized receiving space that accommodates shear webs with varying length dimensions. This parameter change approach allows for tolerance in shear web length while maintaining proper bond accuracy, as the cavity structure compensates for dimensional variations without requiring precise manufacturing of the shear web itself.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The spar cap cavity is pre-formed with specific dimensions that accommodate the shear web. This preliminary action ensures that even if the shear web has dimensional variations, the bond accuracy is maintained through the pre-configured cavity structure, thereby improving ease of manufacture while preserving manufacturing precision.

Inventive Principle:
Principle #10Preliminary action

3Strength

If sufficient bond surface area is provided by increasing shear web width, then the bond strength is improved, but the assembly complexity and time required increase

Engineering Contradiction:
Improvebond strengthVSAvoidassembly time
Core Design Contradiction:
StrengthVSLoss of time

Solution Approach 1:

The shear web is nested within the cavity structure of the spar cap, which provides the necessary bond surface area without requiring the shear web to be wider than necessary. The cavity structure creates the required bond interface through its own geometry, thereby achieving sufficient bond strength while minimizing assembly time and complexity.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The cavity structure changes the effective bond surface area parameter by providing a standardized receiving space. This allows the shear web to have optimized dimensions while still achieving sufficient bond strength through the cavity's geometric configuration, thereby reducing assembly time and complexity while maintaining bond strength.

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

This configuration enhances the reliability and tolerance of the bond between shear webs and spar caps, enabling a simpler, cost-effective assembly process with improved bond strength and reduced need for testing steps, thus addressing the limitations of conventional methods.

Implementation Method 1

a bonding material, which can accommodate length variances and improve the bond strength by distributing stress uniformly

Methodology Applied
Scientific EffectAdhesive bonding: Adhesive

Data Source

PatentEP2878807B1Spar caps-shear web assembly configuration for wind turbine blades, and methods thereof
Publication Date: 2023.04.12 LM WIND POWER AS
  • EP2878807B1 patent drawingFigure 1
  • EP2878807B1 patent drawingFigure 2~3
  • EP2878807B1 patent drawingFigure 4

AI summary

A wind turbine blade is presented. The blade includes an upper shell member 110 having a spar cap 130 disposed on an internal surface of the upper shell, and a lower shell member having a spar cap disposed on an internal surface of the lower shell. The spar cap 130 of the upper shell member, the spar cap of the lower shell member or both the spar caps include at least one cavity structure along a longitudinal length of the blade. A shear web 124 extends between the spar caps 130 along the longitudinal length of the blade, with a transverse end of the shear web 124 positioned in a cavity 140 of the at least one cavity structure, wherein a ratio of a width of the shear web 124 to a bond thickness of the shear web 124 with a side wall of the cavity structure 140 is between about 1:1 and about 15:1.