A multi-frequency fatigue testing method for wind turbine rotor blades

Eder, Maximilian; Belloni, Federico; Tesauro, Angelo; Haniš, Tomáš

doi:10.1016/j.jsv.2016.10.032

Cited by 29 publications

(16 citation statements)

References 5 publications

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“…Furthermore, many full-scale experiments on OWT blades have been widely implemented to obtain the dynamic performance, evaluate fatigue life, and even develop smart fatigue load control methods [164] before they are applied in offshore wind farms. The numerical simulations are always used to verify the reliability of test results [165] or present a novel method to improve the accuracy and efficiency of experiments [166]. Recently, lots of new methods and models on fatigue life prediction and assessment have been discussed.…”

Section: Fatigue Life Assessmentmentioning

confidence: 99%

Health Monitoring and Safety Evaluation of the Offshore Wind Turbine Structure: A Review and Discussion of Future Development

et al. 2019

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With the depletion of fossil energy, offshore wind power has become an irreplaceable energy source for most countries in the world. In recent years, offshore wind power generation has presented the gradual development trend of larger capacity, taller towers, and longer blades. The more flexible towers and blades have led to the structural operational safety of the offshore wind turbine (OWT) receiving increasing worldwide attention. From this perspective, health monitoring systems and operational safety evaluation techniques of the offshore wind turbine structure, including the monitoring system category, data acquisition and transmission, feature information extraction and identification, safety evaluation and reliability analysis, and the intelligent operation and maintenance, were systematically investigated and summarized in this paper. Furthermore, a review of the current status, advantages, disadvantages, and the future development trend of existing systems and techniques was also carried out. Particularly, the offshore wind power industry will continue to develop into deep ocean areas in the next 30 years in China. Practical and reliable health monitoring systems and safety evaluation techniques are increasingly critical for offshore wind farms. Simultaneously, they have great significance for strengthening operation management, making efficient decisions, and reducing failure risks, and are also the key link in ensuring safe energy compositions and achieving energy development targets in China. The aims of this article are to inform more scholars and experts about the status of the health monitoring and safety evaluation of the offshore wind turbine structure, and to contribute toward improving the efficiency of the corresponding systems and techniques.

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Section: Fatigue Life Assessmentmentioning

confidence: 99%

Health Monitoring and Safety Evaluation of the Offshore Wind Turbine Structure: A Review and Discussion of Future Development

et al. 2019

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“…Similarly, Zhang et al (2018) evaluated a different optimization algorithm and included the position of blade tip cut off as a design variable. Eder et al (2017) proposed a uniaxial multi-frequency approach to replicate the actual spatial damage distribution of the blade more realistically.…”

Section: Introductionmentioning

confidence: 99%

A novel rotor blade fatigue test setup with elliptical biaxial resonant excitation

Melcher¹,

Bätge²,

Neßlinger³

2019

Preprint

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Abstract. The full-scale fatigue test of rotor blades is an important and complex part of the development of new wind turbines. It is often done for certification according to the current IEC (2014) and DNV GL AS (2015) standards. Typically, a new blade design is tested by separate uniaxial fatigue tests in both main directions of the blade, i.e. flapwise and lead-lag. These tests are time consuming and rather expensive due to a high number of required load cycles, up to 5 million. Therefore, it is important to run the test as efficiently as possible. During fatigue testing, the rotor blade is excited at or near its resonant frequency. The trend for new rotor blade designs is toward longer blades, leading to a significant drop in their natural frequencies, and a corresponding increase in test time. In order to reduce the total test time, a novel test method aims to combine the two consecutive uniaxial fatigue tests into one biaxial test. The biaxial test excites the blade in both directions at the same time and at the same frequency, resulting in an elliptical deflection path of the blade axis. Using elliptical loading, counting of damage equivalent load cycles is simplified in comparison to biaxial tests with multiple frequencies. In addition, the maximum loads in both main directions remain separated, while off axis loading is introduced. To achieve such a test, specific load elements need to be arranged to equalize the natural frequencies of the test setup for both test directions. This is accomplished by adding stiffness or inertial effects in a specific direction.

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“…Defects in the blade during the process of production would be exposed through fatigue test, such as wrinkle, lace of adhesive paste, rich resin [2][3][4][5][6] . The state-ofthe-art testing method for rotor blades in industry is based on resonance excitation where typically a dynamic mass excites the blade close to its first natural frequency [7][8][9][10] .Due to lack of exciting force during fatigue test in flap wise direction, the blade is difficult to achieve the target bending moment.…”

Section: Introductionmentioning

confidence: 99%

Effects of aerodynamic fairing on full scale blade fatigue test

Pan

Sun³

et al. 2017

IOP Conf. Ser.: Mater. Sci. Eng.

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Abstract.The reliability of large blades should be verified by means of full scale fatigue test. In order to solve the problem of lack of exciting force during fatigue test in the flap wise direction, the program that aerodynamic fairing is installed in the tip of blade to reduce the air resistance is proposed. The numerical model of blade vibration and damping ratio calculation is established. The relationship between damping ratio, exciting force and amplitude is constructed by finite element method respectively. The difference of the exciting bending moment of blade and the damping ratio before and after the installation of aerodynamic fairing is compared respectively. The results show that damping ratio decreased by 27.9%. When the vibration of the blade reaches the target bending moment, the exciting force of the equipment decreases by 45.4%. It is an effective way to reduce the exciting force.

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A multi-frequency fatigue testing method for wind turbine rotor blades

Cited by 29 publications

References 5 publications

Health Monitoring and Safety Evaluation of the Offshore Wind Turbine Structure: A Review and Discussion of Future Development

Health Monitoring and Safety Evaluation of the Offshore Wind Turbine Structure: A Review and Discussion of Future Development

A novel rotor blade fatigue test setup with elliptical biaxial resonant excitation

Effects of aerodynamic fairing on full scale blade fatigue test

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