Pultrusion End Protection for Wind Turbine Blades

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Solution Overview

Problem

Pultruded composite rotor blade components face issues with local stress concentrations and delamination at the ends, which can lead to defects and reduced strength, particularly due to uneven heat treatment during the manufacturing process.

Innovation Solution

A method involving the use of protective caps to prevent heat from concentrating at the ends of pultrusions during surface treatment, such as plasma treatment, and tapering the ends to minimize stress concentrations, followed by infusion in a mold to form blade components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If heat treatment is applied to the surface of pultrusions, then bonding strength is improved, but the thin ends of the pultrusion heat up faster and damage occurs reducing strength in this critical area

Engineering Contradiction:

Improvebonding strengthVSAvoidheat damage to ends

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

A protective cap is introduced as an intermediary element between the heat source and the pultrusion ends. The cap blocks direct heat exposure to the thin ends while allowing the main body to receive heat treatment, thus preventing heat damage while maintaining bonding strength improvement.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The protective cap is applied selectively only to the end portions of the pultrusions, creating different thermal zones: the ends are protected from heat while the main body undergoes heat treatment. This local differentiation resolves the contradiction by applying heat treatment only where beneficial.

Inventive Principle:

Principle #3Local quality

2Reliability

If the pultrusion end is tapered to reduce stress concentrations, then delamination is reduced, but the end thickness becomes significantly less than bulk formed thickness creating vulnerability

Engineering Contradiction:

Improveresistance to delaminationVSAvoidend strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The protective cap serves as a mechanical intermediary that reinforces the tapered ends. It provides structural support to the thinned end sections, compensating for the reduced thickness while maintaining the stress-concentration-reducing geometry.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The protective cap is applied before the infusion process, providing beforehand reinforcement to the vulnerable tapered ends. This pre-protection cushions against potential damage during subsequent manufacturing steps.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Strength

If pultrusions are used to form rotor blade components, then strength and cost-effectiveness are improved, but local stress concentrations occur at the ends causing delamination

Engineering Contradiction:

Improvecomponent strengthVSAvoidresistance to delamination

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The protective cap acts as a mediator between the pultrusion end and the resin infusion process. It prevents direct contact between the tapered end and the resin vacuum bag, eliminating the vacuum bridging issue while maintaining the strength benefits of pultruded composites.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The protective cap is applied to the pultrusion ends before they are placed in the mold for infusion. This preliminary protective measure prevents stress concentrations and delamination from occurring during the subsequent curing process.

Inventive Principle:

Principle #10Preliminary action

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 approach enhances the structural integrity and bonding of pultrusion-based rotor blade components by reducing stress concentrations and preventing delamination, thereby improving the strength and durability of wind turbine rotor blades.

Implementation Method 1

heat treating a surface of the plurality of pultrusions while the protective cap remains over the at least one end

Methodology Applied

Scientific EffectPlasma: Plasma

Implementation Method 2

heat from the treating process can result in the very thin ends of the pultrusion heating up faster than the thicker sections

Methodology Applied

Scientific EffectThermal insulation: Thermal Insulation

Implementation Method 3

pulled through a heated stationary die such that the resin cures or undergoes polymerization

Methodology Applied

Scientific EffectPolymerization: Photopolymerisation

Implementation Method 4

a plurality of pultrusions can be infused together in a mold to form the component

Methodology Applied

Scientific EffectAdhesion: Adhesive

Data Source

PatentUS11969959B2Methods for manufacturing blade components for wind turbine rotor blades

Publication Date: 2024.04.30 GE INFRASTRUCTURE TECH LLC

AI summary

A method of manufacturing a blade component of rotor blade of a wind turbine includes providing a plurality of pultrusions constructed of one or more fibers or fiber bundles cured together via a resin material. The method also includes placing a protective cap over at least one end of one or more of the plurality of pultrusions. Further, the method includes heat treating a surface of the plurality of pultrusions while the protective cap remains over the at least one end. Moreover, the method includes removing the protective cap from the at least one end. The method further includes arranging the plurality of pultrusions in a mold of the blade component. In addition, the method includes infusing the plurality of pultrusions together so as to form the rotor blade component.