Wind Turbine Rotor Blade Fatigue Testing Actuator Arrangement

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Solution Overview

Problem

Conventional wind turbine rotor blade fatigue testing methods are inefficient due to the high cost and short operational lifespan of ground-based exciters, which require expensive gearboxes and push rods, and are limited by the need for small stroke lengths and high forces, leading to suboptimal test results and rapid gearbox wear.

Innovation Solution

A method and arrangement for fatigue testing where an actuator attached to the rotor blade moves a mass in a reciprocating manner, using a bendable holding material like a rope or string to convert rotational movement into linear movement, allowing for adjustable torque and rotational speed, and eliminating the need for a gearbox, thus reducing costs and improving test accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional ground-based exciter with gearbox and push rod is used, then the rotor blade can be tested for fatigue, but the equipment is expensive and has short operational lifespan due to gearbox wear

Engineering Contradiction:

Improveoperational lifespan of exciterVSAvoidcomplexity of exciter system

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent removes the gearbox from the exciter system entirely, extracting the problematic component that caused wear and short operational lifespan. The exciter now directly drives the push rod without any intermediate gearing, eliminating the source of mechanical wear while maintaining the essential testing functionality.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of using a gearbox to reduce motor speed and increase torque, the patent inverts the approach by using a high-speed motor with a long-stroke push rod. The motor operates at its optimal high speed, and the reciprocating motion is achieved through the push rod's oscillating movement rather than through gear reduction.

Inventive Principle:

Principle #13The other way round (Inversion)

2Ease of operation

If the exciter is placed close to the blade tip to achieve small stroke lengths, then the test configuration is optimized, but high forces are required which increase equipment cost

Engineering Contradiction:

Improvetest configuration optimizationVSAvoidexcitation force required

Core Design Contradiction:

Ease of operationVSForce

Solution Approach 1:

The patent changes the dimensional approach by placing the exciter at the blade root rather than near the tip. This positional change in another dimension (location along the blade) allows the use of lower forces while still achieving effective fatigue testing, as the root location provides better mechanical advantage and structural support.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent changes the stroke length parameter to be long rather than short, which is the opposite of conventional approaches. This parameter change allows the exciter to operate at the blade root with lower forces, as the long stroke accommodates the larger movement capability available at the root location while still producing effective fatigue loads.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If a long push rod is used to connect the exciter to the blade, then the exciter can be placed at the root, but the push rod must be configured to withstand and transfer big forces

Engineering Contradiction:

Improveexciter placement flexibilityVSAvoidpush rod strength requirement

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The patent inverts the conventional approach by using a long-stroke push rod that oscillates with large amplitude rather than a short-stroke push rod. This inversion allows the push rod to operate in tension and compression along its length, distributing the forces more effectively and reducing the peak stress requirements while maintaining the ability to transfer sufficient force for fatigue testing.

Inventive Principle:

Principle #13The other way round (Inversion)

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 enables cost-effective, efficient fatigue testing of wind turbine rotor blades by allowing high excitation forces near the root, avoiding gearbox reversals, and providing flexible testing configurations without the need for expensive gearboxes or push rods, resulting in improved test results and extended equipment lifespan.

Implementation Method 1

Methodology Applied

Scientific EffectRotational to linear motion conversion:

Implementation Method 2

using a bendable holding material like a rope or string to convert rotational movement into linear movement

Methodology Applied

Scientific EffectMechanical energy conversion through flexible material:

Data Source

PatentUS11754053B2Rotor blade fatigue testing

Publication Date: 2023.09.12 SIEMENS GAMESA RENEWABLE ENERGY AS

AI summary

Provided is a method and an arrangement of fatigue testing of a wind turbine rotor blade, the method including: operating an actuator attached to the rotor blade, thereby moving a mass connected to the actuator in a reciprocating manner. The mass may be a hanging mass, for example, hanging down from the actuator.