Interleaved Composite Joint for Wind Turbine Blade Load Transfer

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Solution Overview

Problem

Conventional wind turbine blade manufacturing methods require a high number of complex parts and accurate machining, making it difficult to connect span-wise blade sections efficiently and effectively transfer loads across the blade.

Innovation Solution

A wind turbine blade design featuring a connection joint with interleaved layers and fasteners, where the layers have cutouts for clearance fit, allowing for a compact, lightweight, and easy-to-assemble joint that transfers loads primarily through friction, using composite and metal layers to maintain aerodynamic performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional connection methods with multiple parts are used, then load transfer capability is improved, but device complexity increases and manufacturing precision requirements increase

Engineering Contradiction:
Improveload transfer capabilityVSAvoidparts count
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent merges multiple separate connection parts into a single integrated connection element that includes both the connection body and connection arms as one piece. This reduces the total parts count while maintaining the load transfer capability through the integrated structure's geometric design that provides both connection functions in a unified component.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The connection element is segmented into functional zones within a single component - the connection body portion for receiving the fastener and the connection arm portions for engaging with blade sections. This segmentation of functions within a unified structure reduces part count while preserving load transfer pathways.

Inventive Principle:
Principle #1Segmentation

2Strength

If conventional connection methods with multiple parts are used, then load transfer capability is improved, but manufacturing precision requirements increase

Engineering Contradiction:
Improveload transfer capabilityVSAvoidmachining accuracy
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The patent changes the manufacturing approach from precision machining of multiple metal parts to forming a single connection element with optimized geometric parameters. The connection element's dimensions, arm angles, and feature locations are designed as optimized parameters that provide adequate load transfer without requiring tight tolerances, as the integrated structure distributes loads more evenly.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The connection element is designed as a simpler, more economical component that can be manufactured using less precise, more cost-effective processes. The design accepts some variability in dimensions while maintaining functional performance, reducing the need for expensive precision machining and inspection.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Ease of manufacture

If interleaved layers with cutouts are used, then ease of manufacture is improved, but structural complexity increases

Engineering Contradiction:
Improveassembly simplicityVSAvoidjoint construction complexity
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The joint construction is segmented into discrete interleaved layers, each with a simple cutout pattern. This segmentation allows each layer to be manufactured independently and then assembled by simple interleaving, reducing assembly complexity despite the multi-layer structure. The repetitive cutout pattern across layers creates a modular assembly process.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The cutouts are pre-formed in each layer during manufacturing, so that during assembly the layers can be directly interleaved without additional machining or alignment operations. This preliminary action of creating the cutouts simplifies the final assembly process, as the layers naturally guide themselves into position through the interlocking cutout patterns.

Inventive Principle:
Principle #10Preliminary action

4Ease of manufacture

If friction-based load transfer is used, then ease of manufacture is improved, but reliability may be reduced

Engineering Contradiction:
Improvejoint construction simplicityVSAvoidload transfer consistency
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The joint uses composite construction with interleaved layers of different materials (metal layers and composite material layers) that work together to transfer loads. The metal layers provide friction-based load transfer while the composite layers provide structural continuity and additional load paths, creating a hybrid system that maintains reliability through material diversity rather than relying solely on friction.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

Different regions of the joint have different load transfer mechanisms - the interleaved interfaces rely on friction while the continuous portions of layers provide direct load paths. This local differentiation of quality allows the joint to use simple friction-based assembly at critical interfaces while maintaining overall reliability through distributed load paths throughout the joint structure.

Inventive Principle:
Principle #3Local quality

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 solution reduces the complexity of blade assembly, enhances load transfer efficiency, and maintains aerodynamic performance by using a comb-like frictional connection that can handle up to 100% of the load through friction, while being easy to manufacture and disassemble.

Implementation Method 1

transfers loads primarily through friction

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3997331B1Connection for split wind turbine blade
Publication Date: 2023.06.07 VESTAS WIND SYSTEMS AS
  • EP3997331B1 patent drawingFigure 1
  • EP3997331B1 patent drawingFigure 2
  • EP3997331B1 patent drawingFigure 3~4

AI summary

A wind turbine blade has a first blade portion and a second blade portion, each blade portion having a spar cap portion. A connection joint for coupling the first and second blade portions together includes first layers associated with the first spar cap portion and second layers associated with the second spar cap portion. The first and second layers each have a cut out at one end and are interleaved with their cut outs aligned. Fasteners pass through the cut outs of the first and second layers and are tensioned to clamp together the interleaved layers between the first and second blade portions.