Rotor Blade Test Stand Spring Stiffening

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current test stands for rotor blades, particularly those for wind turbines, require extended test durations due to limitations in reducing the oscillating mass and increasing the natural frequency, leading to prolonged testing times.

Innovation Solution

A test stand design that includes a support structure with spring elements connected between a stationary pivot point and the rotor blade, allowing for increased rigidity and natural frequency, with the spring elements arranged to apply forces parallel or perpendicular to the rotor blade's main loading direction, and optionally using a transmission gear to amplify deflections, thereby reducing test time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If the oscillating mass is reduced to increase natural frequency, then test duration is reduced, but the oscillating mass cannot be reduced below a certain limit

Engineering Contradiction:

Improvetest durationVSAvoidoscillating mass

Core Design Contradiction:

Loss of timeVSWeight of moving object

Solution Approach 1:

The patent replaces the traditional mechanical excitation system (rotating masses mounted on the blade) with a hydraulic excitation system. The hydraulic cylinder applies forces directly to the blade without adding significant oscillating mass, thereby enabling higher natural frequencies and shorter test durations while minimizing the addition of moving mass.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a hydraulic fluid as an intermediary between the power source and the rotor blade. The hydraulic system transmits force to the blade without requiring heavy mechanical components to be mounted on the blade itself, thus reducing the oscillating mass while maintaining effective excitation capability.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If excitation units are mounted on the rotor blade to initiate vibration, then vibration can be applied, but the vibrating mass increases and natural frequency decreases

Engineering Contradiction:

Improvevibration application capabilityVSAvoidvibrating mass

Core Design Contradiction:

Ease of operationVSWeight of moving object

Solution Approach 1:

The patent extracts the excitation mechanism from the rotor blade structure itself and relocates it to an external hydraulic system. The hydraulic cylinder is positioned separately and applies force to the blade through a lever arm or direct connection, removing the need for heavy rotating masses to be mounted on the blade, thus reducing the vibrating mass while maintaining vibration application capability.

Inventive Principle:

Principle #2Taking out (Extraction)

3Ease of operation

If traditional excitation units with rotating eccentric masses are used, then vibration can be generated, but the test time is prolonged due to increased oscillating mass

Engineering Contradiction:

Improvevibration generation capabilityVSAvoidtest time

Core Design Contradiction:

Ease of operationVSLoss of time

Solution Approach 1:

The patent substitutes the mechanical rotating eccentric mass system with a hydraulic actuation system. The hydraulic cylinder can generate the required vibrational forces without the inertia constraints of rotating masses, enabling faster testing by operating at higher natural frequencies determined by the blade's inherent properties rather than the excitation system's mass.

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

This design significantly reduces test duration by increasing the natural frequency of the rotor blade, allowing for faster completion of tests while simulating realistic cyclic and static loads, thus improving the efficiency and realism of the testing process.

Implementation Method 1

at least one spring element (13) of the test stand is connected between a point of articulation (14) that is stationary during testing and the rotor blade (10), fastened to a point of articulation and can be connected to the rotor blade for test mode in such a way that the rotor blade (10) can be subjected to a spring force by the spring element (13) to influence the vibration behavior

Methodology Applied

Scientific EffectSpring force: Spring

Data Source

PatentEP2741068B1Test bench for a rotor blade, assembly with such a test bench and a method for operating such a test bench

Publication Date: 2016.11.02 INDUSTRIEANLAGEN BETRIEBSGESELLSCHAFT MBH

Figure 1~2
Figure 3
Figure 4~5

AI summary

The test stand has a support structure (15) which is fastened at one axial end of a rotor blade (10). A stimulation unit is connected with rotor blade for excitation of oscillation of the rotor blade. A spring element (13) is fixed to a stationary articulation portion (14) and to the rotor blade, such that the rotor blade is acted upon to the influence of the vibration behavior by spring element with spring force whose force direction has a component that is parallel to main load direction of rotor blade. An independent claim is included for a method for operating test stand or test stand assembly.