Segmented Rotor Blade Joint With Pre-Loaded Composite Beam Fit

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Solution Overview

Problem

Conventional joint designs for connecting segmented wind turbine rotor blades are heavy due to metallic fasteners, increasing weight and susceptibility to lightning strikes, and are labor-intensive and prone to defects.

Innovation Solution

A pre-loaded joint configuration using composite materials, such as fiber-reinforced composites, with pre-loaded beams and compression members that create an interference fit between blade segments, reducing the need for metallic hardware and allowing for effective load transfer and alignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If mechanical fasteners (bolts, nuts, pins) are used to secure blade segments together, then the blade segments can be connected, but the overall weight of the rotor blade significantly increases

Engineering Contradiction:
Improveconnection reliabilityVSAvoidrotor blade weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The patent replaces traditional mechanical fasteners (bolts, nuts, pins) with a pre-loaded beam system that uses elastic deformation and interference fit to connect blade segments. The pre-loaded beam is compressed between opposing structural components, creating friction-based load transfer rather than mechanical fastening, thereby eliminating heavy metallic hardware while maintaining connection reliability.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The pre-loaded beam is constructed from composite materials that provide both structural strength and elastic properties. These composite materials enable the beam to deform elastically under compression and maintain the interference fit, replacing metallic fasteners with a lighter, multi-material solution that achieves reliable connection without the weight penalty of traditional mechanical fasteners.

Inventive Principle:
Principle #40Composite materials

2Reliability

If mechanical fasteners are used to connect blade segments, then the segments can be secured, but the likelihood of lightning strikes increases due to metallic components

Engineering Contradiction:
Improveconnection reliabilityVSAvoidlightning strike susceptibility
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent eliminates metallic fasteners that attract lightning strikes by replacing them with a pre-loaded beam system made of non-conductive or less conductive composite materials. The connection reliability is maintained through elastic deformation and friction-based load transfer, removing the harmful metallic components that serve as lightning attractors while preserving the structural connection function.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Ease of manufacture

If conventional manufacturing methods are used for large rotor blades, then the blades can be manufactured, but the process becomes highly labor intensive and defect prone

Engineering Contradiction:
Improvemanufacturing feasibilityVSAvoidassembly efficiency
Core Design Contradiction:
Ease of manufactureVSProductivity

Solution Approach 1:

The patent divides the rotor blade into multiple blade segments that can be manufactured separately using standardized processes, then connected through the pre-loaded beam system. This segmentation allows each segment to be manufactured more efficiently with controlled processes, reducing labor intensity and defect rates compared to manufacturing one large blade, while the pre-loaded beam connection enables quick and reliable assembly.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The pre-loaded beam is pre-compressed and installed in a controlled manner before final blade assembly, creating an interference fit that simplifies the connection process. This preliminary action of pre-loading the beam allows for easier alignment and connection of blade segments, reducing assembly labor and improving productivity compared to traditional post-assembly fastening methods.

Inventive Principle:
Principle #10Preliminary action

4Reliability

If blade segments are joined using traditional methods, then the segments can be connected, but the process is susceptible to defects and requires high labor intensity

Engineering Contradiction:
Improvejoint integrityVSAvoidassembly complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical fastening systems with a simpler pre-loaded beam insertion system. The beam is compressed between opposing structural components, creating a self-aligning interference fit that reduces assembly complexity. The elastic properties of the composite beam provide automatic load distribution and defect tolerance, maintaining joint integrity while simplifying the assembly process compared to traditional multi-step fastening procedures.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 weight, minimizes lightning strikes, enhances assembly efficiency, and provides a flexible, elastic support interface for rotor blades, while maintaining structural integrity and load distribution.

Implementation Method 1

a pre-loaded beam extending outwardly from the second joint end of the second blade segment across the joint interface such that the pre-loaded beam is received within an interior of the first blade segment. The pre-loaded beam may be compressed between the first pair of opposed internal structural components

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3788251B1Improved joint configuration for a segmented wind turbine rotor blade
Publication Date: 2025.12.03 LM WIND POWER AS
  • EP3788251B1 patent drawingFigure 1
  • EP3788251B1 patent drawingFigure 2
  • EP3788251B1 patent drawingFigure 3

AI summary

A rotor blade assembly for a wind turbine may include a first blade segment having a first joint end and a second blade segment having a second joint end, with the blade segments being coupled together such that the first and second joint ends are located at or adjacent to a joint interface between the blade segments. The blade assembly may also include a pre-loaded beam extending outwardly from the second blade segment across the joint interface such that the pre-loaded beam is received within the first blade segment. The pre-loaded beam may be compressed between the opposed internal structural components of the first blade segment such that a first engagement interface is defined between a first side of the pre-loaded beam and the first internal structural component and a second engagement interface is defined between an opposed second side of the pre-loaded beam and the second internal structural component.