Wind turbine blades inspection techniques
TL;DR: In this paper the techniques which are already used or are implementable for non-destructive examination of wind turbine blades will be presented shortly and new electromagnetic techniques like active IR testing or terahertz imaging will be more widely presented and some exemplary results of inspections will be shown.
Abstract: Wind turbines are complex composite structures, which condition should be constantly tested. In this paper the techniques which are already used or are implementable for non-destructive examination of wind turbine blades will be presented shortly. New electromagnetic techniques like active IR testing or terahertz imaging will be more widely presented and some exemplary results of inspections will be shown. Streszczenie. Turbiny wiatrowe są złożonymi strukturami kompozytowymi, których stan powinien być stale badany. W niniejszym opracowaniu krótko przedstawiono metody nieniszczącego badania łopat turbin wiatrowych, które są obecnie stosowane lub są możliwe do wdrożenia. Nowe techniki wykorzystujące zjawiska elektromagnetyczne, jak aktywna inspekcja w podczerwieni, czy obrazowanie terahercowe, zostaną szerzej omówione. Zaprezentowane zostaną również przykładowe wyniki badań. Metody nieniszczącego badania łopat turbin wiatrowych
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TL;DR: Microwave non-destructive testing has received extensive attention in recent years owing to its advantages of non-contact inspection, no need for a coupling medium or sensors attached on the microwave as discussed by the authors.
Abstract: Microwave non-destructive testing has received extensive attention in recent years owing to its advantages of non-contact inspection, no need for a coupling medium or sensors attached on th...
18 citations
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TL;DR: In this paper, the potential of the use of hyperspectral imaging system in the detection of wind turbine blade damage and icing incident is introduced, and the types of damage, its causes and the techniques used to detect it.
Abstract: Despite the enhancement in the wind energy sector, the wind turbine industry still faces certain limitations due to some manufacturing and environmental factors. Blades are one of the major components of the wind turbine. During their lifetime, these blades are susceptible to deterioration and normal wear and tear that limit their efficiency and result in higher maintenance costs and longer turbine downtime. Periodic inspections must be performed to detect faults at an early stage and help in mitigating these shortcomings. Many methods were used for this purpose such as: ultrasound, sonic IR, vibration analysis and others. Recent developments have seen a trend of using remote inspection techniques that eliminate the need for human access to the blades. Hyperspectral imaging or imaging spectroscopy is a non-destructive and fast monitoring technique in remote sensing. It is widely used in various classification, and detection fields. In this study, the potential of the use of hyperspectral imaging system in the detection of wind turbine blade damage and icing incident is introduced. Specifically, this study lists the types of damage, its causes, and the techniques used to detect it. Finally, current problems and promising attempts for analyzing real-time turbine blade damage detection are discussed. The results demonstrated that hyperspectral imaging could detect surface and subsurface defects as well as icing events in their early stages of occurrence.
12 citations
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TL;DR: In this paper, the most promising ultrasonic signal processing methods (discrete wavelet transform, variational mode decomposition and Hilbert transform) are applied for the analysis of disbond-type durations.
Abstract: In this work, the most promising ultrasonic signal processing methods—discrete wavelet transform, variational mode decomposition and Hilbert transform—are applied for the analysis of disbond-type d...
10 citations
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TL;DR: In this article, the recent research progress is reviewed, identifying achievements and challenges, and representative case studies are presented, including intelligent/automated inspection and solid-state heating, which can offer volumetric heating, reduced processing time and energy saving with no ionising hazards.
Abstract: Microwaves are a form of electromagnetic radiation commonly used for telecommunications, navigation and food processing. More recently microwave technologies have found applications in fibre-reinforced polymer composites, which are increasingly used in aircraft structures. Microwave energy can be applied with low power (up to milliwatts) for non-destructive testing and high power (up to kilowatts) for heating/curing purposes. The state-of-the-art applications at high power include curing, three-dimensional (3D) printing, joining and recycling, whereas low-power microwave techniques can provide quality checks, strain sensing and damage inspection. Low-power microwave testing has the advantage of being non-contact, there is no need for surface transducers or couplants, it is operator friendly and relatively inexpensive; high-power microwave energy can offer volumetric heating, reduced processing time and energy saving with no ionising hazards. In this paper the recent research progress is reviewed, identifying achievements and challenges. First, the critical electromagnetic properties of composites that are closely related to the heating and sensing performance are discussed. Then, representative case studies are presented. Finally, the trends are outlined, including intelligent/automated inspection and solid-state heating.
8 citations
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TL;DR: In this article, an image processing technique for ultrasonic B-scan images is presented to improve the estimation of the location and size of disbond-type defects in glass fiber-reinforced plastic materials with 25mm and 51mm diameters.
Abstract: The estimation of the size and location of defects in multi-layered composite structures by ultrasonic non-destructive testing using guided waves has attracted the attention of researchers for the last few decades. Although extensive signal processing techniques are available, there are only a few studies available based on image processing of the ultrasonic B-scan image to extract the size and location of defects via the process of ultrasonic non-destructive testing. This work presents an image processing technique for ultrasonic B-scan images to improve the estimation of the location and size of disbond-type defects in glass fiber-reinforced plastic materials with 25-mm and 51-mm diameters. The sample is a segment of a wind turbine blade with a variable thickness ranging from 3 to 24 mm. The experiment is performed by using a low-frequency ultrasonic system and a pair of contact-type piezoceramic transducers kept apart by a 50-mm distance and embedded on a moving mechanical panel. The B-scan image acquired by the ultrasonic pitch-catch technique is denoised by utilizing features of two-dimensional discrete wavelet transform. Thereafter, the normalized pixel densities are compared along the scanned distance on the region of interest of the image, and a −3 dB threshold is applied to the locations and sizes the defects in the spatial domain.
7 citations
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References
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TL;DR: The latest results in tomographic imaging, in which waveforms reflected from an object can be used to form a three-dimensional representation, are described and substantial improvements in the spatial resolution are demonstrated.
Abstract: We review recent progress in the field of terahertz “T-ray” imaging. This relatively new imaging technique, based on terahertz time-domain spectroscopy, has the potential to be the first portable far-infrared imaging spectrometer. We give several examples which illustrate the possible applications of this technology, using both the amplitude and phase information contained in the THz waveforms. We describe the latest results in tomographic imaging, in which waveforms reflected from an object can be used to form a three-dimensional representation. Advanced signal processing tools are exploited for the purposes of extracting tomographic results, including spectroscopic information about each reflecting layer of a sample. We also describe the application of optical near-field techniques to the THz imaging system. Substantial improvements in the spatial resolution are demonstrated.
690 citations
"Wind turbine blades inspection tech..." refers methods in this paper
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TL;DR: In this article, the current state of NDT of wind turbines at manufacture and in-service, and the most promising NDT methods for detecting flaws of most concern are reviewed.
Abstract: Wind machines and traditional 'Dutch' windmills preceded electricity supply and were used for grinding grain They were always attended, sometimes inhabited and, largely, manually controlled They were integrated within the community, designed for frequent replacement of certain components and efficiency was of little importance Wind turbines have been in use since 1941 The function of a modern power-generating wind turbine is to generate high quality, network frequency electricity There is information and advice on the non-destructive testing (NDT) of wind turbines in Europe and internationally, but because mass production of wind turbines is fairly new, no manufacturing standards have been set yet There is also a need for European standards, in the testing, certification and accreditation of turbines and components The main objectives in this paper are to review the current state of NDT of wind turbines at manufacture and in-service, and to establish the most promising NDT methods for detecting flaws of most concern
75 citations
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16 Jun 2008
TL;DR: The objective of this study is review of different NDT techniques, which are used, or could be used for non-destructive testing of wind turbine blades, taking into account the complicated structure of the wind turbines as well as possibility to make non- destructive testing in harsh on-site conditions.
Abstract: Wind power is a promising source of environmentally safe and renewable energy with a high potential. However, in order to fully exploit energy of wind power the construction elements of the wind turbine should be inspected periodically. Wind turbine blades are complicated objects for inspection because they have an arbitrary curved surface, are multi-layered, have variable thickness and are made from anisotropic materials.The presented study covers an overview of the techniques which are used or could be used for on site condition monitoring and effective NDT of wind turbine blades. Inspection methods based on vibration analysis, thermography, X-ray imaging, acoustic emission and ultrasound are reviewed. The objective of this study is review of different NDT techniques, which are used, or could be used for non-destructive testing of wind turbine blades, taking into account the complicated structure of the wind turbine blades as well as possibility to make non-destructive testing in harsh on-site conditions.
73 citations
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TL;DR: In this paper, a new image processing technique was investigated to assess its ability to detect surface flaws on an on-tower wind turbine blade (WTB) using computer-based optical inspection.
Abstract: A new image processing technique was investigated to assess its ability to detect surface flaws on an on-tower wind turbine blade (WTB). The method was tested by varying the parameters of the surface flaws as well as the parameters of the method. It was found that detecting and quantifying cracks as small as hair thickness with computer-based optical inspection is feasible and the orientation of a crack was not sensitive to image processing so that the inspection camera does not need to be set up at a specific angle to detect cracks. It was also found that uneven background illumination was significantly reduced by optimizing the threshold value using the Canny method. In addition, the accuracy of quantifying a crack was improved by reducing noise with the intersection of two processed images from Sobel and Canny methods.
12 citations
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