Damage detection in wind turbine blades by using operational modal analysis

Lorenzo, Emilio Di; Petrone, Giuseppe; Manzato, Simone; Peeters, Bart; Desmet, Wim; Marulo, Francesco

doi:10.1177/1475921716642748

“…Across literature both methods, in their simplest forms, have been shown successful on simple structures subjected to testing in a laboratory setting but struggle with large scale, practical applications due low damage sensitivity, environmental and operational variability, and sparse measurement arrays [28][29][30].…”

Section: Overview Of Structural Health Monitoringmentioning

confidence: 99%

Ambient Excitation Based Model Updating for Structural Health Monitoring via Dynamic Strain Measurements

Martins

¹

,

Kosmatka

²

2018

2018 AIAA/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference

0

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“…Traditional contact transducers such as strain gauges and accelerometers have been used for vibration analysis, health monitoring, damage detection and structural displacement of wind turbines (Weijtjens et al, 2017;Yang et al, 2014;Osgood et al, 2010;Lorenzo et al, 2016; and other large structures like bridges (Hoffmann, 1989;Fukuda et al, 2013;Park et al, 2005;Ye et al, 2012;Xia et al, 2014, andSiriwardane, 2015), but they have difficulties measuring on a large scale; the installation process, which often includes wiring, is costly and time consuming. The measured signal from conventional sensors such as accelerometers is not very accurate in measuring low frequencies of the structure (for instance frequencies between 0.2 and 0.5 Hz in horizontal-axis wind turbines) and includes the centrifugal components (Najafi and Paulsen, N. Najafi and A. Vesth: Establishing a robust testing approach for displacement measurement 2017).…”

Section: Introductionmentioning

confidence: 99%

Establishing a robust testing approach for displacement measurement on a rotating horizontal-axis wind turbine

Najafi

¹

,

Vesth

²

2018

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Abstract. Health monitoring by conventional sensors like accelerometers or strain gauges becomes challenging for large rotating structures due to the issues with feasibility, sensing and data transmission. In addition, acceleration measurements have low capability of presenting very small frequencies, which happen very often for large structures (for instance, frequencies between 0.2 and 0.5 Hz in horizontal-axis wind turbines). By contrast, displacement measurement using stereo vision is rapid, non-contacting and distributed over the structure. The sensors are cheaper and more easily applied to many places on the object to be measured. Horizontal-axis wind turbines are one of the most important large rotating structures and need to be measured and monitored in time to prevent damage and failure, and the blade tip position is one of the key parameters to measure in order to prevent the blade hitting the turbine tower. This paper presents a clearly described and easily applicable procedure for measuring the displacement on the components of a rotating horizontal-axis wind turbine with stereophotogrammetry. Paper markers have been applied on the rotor and tower of a scaled-down horizontal-axis wind turbine model in the workshop and the displacement measurement method has been demonstrated by measuring displacement during operation. The method is mainly developed in two parts: (1) camera calibration and (2) tracking algorithm. We introduce an efficient camera calibration method for measurement in large fields of view, which has always been a challenge. This method is easy and practical and offers better accuracy compared with 2-D traditional camera calibration. The tracking algorithm also works successfully and is able to track the points during rotation within the measurement time. Finally, the accuracy analysis has been conducted and has shown better accuracy of the new calibration method compared with 2-D traditional camera calibration.

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“…Traditional contact transducers such as strain gauges and accelerometers have been used for vibration analysis, health monitoring, damage detection and structural displacement of wind turbines (Weijtjens et al, 2017;Yang et al, 2014;Osgood et al, 2010;Lorenzo et al, 2016; and other large structures like bridges (Hoffmann, 1989;Fukuda et al, 2013;Park et al, 2005;Ye et al, 2012;Xia et al, 2014, andSiriwardane, 2015), but they have difficulties measuring on a large scale; the installation process, which often includes wiring, is costly and time consuming. The measured signal from conventional sensors such as accelerometers is not very accurate in measuring low frequencies of the structure (for instance frequencies between 0.2 and 0.5 Hz in horizontal-axis wind turbines) and includes the centrifugal components (Najafi and Paulsen, 2017).…”

Section: Introductionmentioning

confidence: 99%

Point to point response to reviewers 3

Anonymous

2018

Preprint

0

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Health monitoring by conventional sensors like accelerometers or strain gauges becomes challenging for large rotating structures due to the issues with feasibility, sensing and data transmission. In addition, acceleration measurements have low capability of presenting very small frequencies, which happen very often for large structures (for instance, frequencies between 0.2 and 0.5 Hz in horizontal-axis wind turbines). By contrast, displacement measurement using stereo vision is rapid, non-contacting and distributed over the structure. The sensors are cheaper and more easily applied to many places on the object to be measured. Horizontal-axis wind turbines are one of the most important large rotating structures and need to be measured and monitored in time to prevent damage and failure, and the blade tip position is one of the key parameters to measure in order to prevent the blade hitting the turbine tower.This paper presents a clearly described and easily applicable procedure for measuring the displacement on the components of a rotating horizontal-axis wind turbine with stereophotogrammetry. Paper markers have been applied on the rotor and tower of a scaled-down horizontal-axis wind turbine model in the workshop and the displacement measurement method has been demonstrated by measuring displacement during operation. The method is mainly developed in two parts: (1) camera calibration and (2) tracking algorithm. We introduce an efficient camera calibration method for measurement in large fields of view, which has always been a challenge. This method is easy and practical and offers better accuracy compared with 2-D traditional camera calibration. The tracking algorithm also works successfully and is able to track the points during rotation within the measurement time. Finally, the accuracy analysis has been conducted and has shown better accuracy of the new calibration method compared with 2-D traditional camera calibration.Published by Copernicus Publications on behalf of the European Academy of Wind Energy e.V.

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Damage detection in wind turbine blades by using operational modal analysis

Cited by 55 publications

References 26 publications

Ambient Excitation Based Model Updating for Structural Health Monitoring via Dynamic Strain Measurements

Ambient Excitation Based Model Updating for Structural Health Monitoring via Dynamic Strain Measurements

Establishing a robust testing approach for displacement measurement on a rotating horizontal-axis wind turbine

Point to point response to reviewers 3

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