Download or read book Fatigue Data Editing for Blades of Horizontal Axis Wind Turbines written by Pratumnopharat Panu and published by LAP Lambert Academic Publishing. This book was released on 2015-11-12 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: In predicting performance of wind turbines, the blade element momentum (BEM) theory is still commonly used by wind turbine designers and researchers. This book deals with several up-to-date models added to the BEM theory to get more realistic prediction. In evaluating fatigue damage of wind turbine blade, stress-life approach and Miner's linear cumulative damage rule are mentioned. Wind turbine blades are the most critical components of HAWT. Full-scale blade fatigue testing is required to verify that the blades possess the strength and service life specified in the design. Unfortunately, the test must be run for a long time period. This problem led the blade testing laboratories to accelerate fatigue testing time. To achieve the objective, two novel methods called STFT- and WT-based fatigue damage part extracting methods are used to generate the edited stress-time history. Blade testing laboratories can use this history to accelerate fatigue testing time. STFT- and WT-based fatigue damage part extracting methods proposed in this book are suggested as alternative methods in accelerating fatigue testing time, especially for the field of wind turbine engineering.

Download or read book Novel Methods for Fatigue Data Editing for Horizontal Axis Wind Turbine Blades written by Panu Pratumnopharat and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Wind turbine blades are the most critical components of wind turbines. Full-scale blade fatigue testing is required to verify that the blades possess the strength and service life specified in the design. Unfortunately, the test must be run for a long time period. This problem led the blade testing laboratories to accelerate fatigue testing time. To achieve the objective, this thesis proposes two novel methods called STFT- and WT-based fatigue damage part extracting methods which are based on short-time Fourier transform (STFT) and wavelet transform (WT), respectively. For WT, different wavelet functions which are Morl, Meyr, Dmey, Mexh and DB30 are studied. An aerodynamic computer code, HAWTsimulator, based on blade element momentum theory has been developed. This code is used to generate the sets of aerodynamic loads acting along the span of a 'SERI-8 wind turbine blade' in the range of wind speed from cut-in to cut-out. SERI-8 blades are installed on 65 kW wind turbines. Each set of aerodynamic loads is applied on the finite element model of the SERI-8 blade in structural software (ANSYS) to generate a plot of von Mises stress at the critical point on the blade versus wind speed. By relating this relationship to the wind speed data, the stress-time history at the critical point on the SERI-8 blade can be generated. It has the same sampling rate and length as the wind speed data. A concept of applying accumulative power spectral density (AccPSD) distribution with time to identify fatigue damage events contained in the stress-time history has been introduced in this thesis. For STFT, AccPSD is the sum of power spectral density (PSD) of each frequency band at each time interval in the spectrogram. For WT, AccPSD is the sum of PSD of wavelet coefficients of each scale at each time interval in the scalogram. It has been found that the locations of AccPSD spikes imply where the fatigue damage events are. Based on an appropriate AccPSD level called a cutoff level, the fatigue damage events can be identified at time location of the stress-time history. A fatigue computer code, HAWTfatigue, based on stress-life approach and Miner's linear cumulative damage rule has been developed. Basically, the code is used for evaluating the fatigue damage and service lifetime of horizontal axis wind turbine blade. In addition, the author has implemented STFT- and WT-based fatigue damage part extracting methods into the code. Fatigue damage parts are extracted from the stress time history and they are concatenated to form the edited stress-time history. The effectiveness of STFT- and WTbased algorithms is performed by comparing the reduction in length and the difference in fatigue damage per repetition of the edited stress-time histories generated by STFT and WT to those of the edited stress-time history generated by an existing method, Time Correlated Fatigue Damage (TCFD) used by commercial software. The findings of this research project are as follows: 1. The comparison of the reduction in length of the edited stress-time histories generated by TCFD, STFT and WT indicates that WT with the Mexh wavelet has the maximum reduction of 20.77% in length with respect to the original length, followed by Meyr (20.24%), Dmey (19.70%), Morl (19.66%), DB30 (19.19%), STFT (15.38%), and TCFD (10.18%), respectively. 2. The comparison of the retained fatigue damage per repetition in the edited stress-time histories generated by TCFD, STFT and WT indicates that TCFD has the retained fatigue damage per repetition less than the original fatigue damage per repetition by 0.076%, followed by Mexh (0.068%), DB30 (0.063%), STFT (0.045%), Meyr (0.032%), Dmey (0.014%), and Morl (0.013%), respectively. 3. Both comparison of reduction in length and comparison in the retained fatigue damage per repetition of the edited stress-time histories suggest that WT is the best method for extracting fatigue damage parts from the given stress-time history. It has also been indicated that not only do STFT and WT improve accuracy of fatigue damage per repetition retained in the edited stress-time histories, but also they provide the length of the edited stress-time histories shorter than TCFD does. Thus, STFT and WT are useful methods for performing accelerated fatigue tests. 4. It has been found that STFT is controlled by two main factors which are window size and cutoff level. Also, WT is controlled by three main factors which are wavelet decomposition level, cutoff level and wavelet type. To conclude, the edited stress-time history can be used by blade testing laboratories to accelerate fatigue testing time. STFT- and WT-based fatigue damage part extracting methods proposed in this thesis are suggested as alternative methods in accelerating fatigue testing time, especially for the field of wind turbine engineering.

Download or read book Proceedings of the 7th International Conference on Fracture Fatigue and Wear written by Magd Abdel Wahab and published by Springer. This book was released on 2018-07-14 with total page 831 pages. Available in PDF, EPUB and Kindle. Book excerpt: These proceedings gather a selection of peer-reviewed papers presented at the 7th International Conference on Fracture Fatigue and Wear (FFW 2018), held at Ghent University, Belgium on 9–10 July 2018. The contributions, prepared by international scientists and engineers, cover the latest advances in and innovative applications of fracture mechanics, fatigue of materials, tribology and wear of materials. The book is intended for academics, including graduate students and researchers, as well as industrial practitioners working in the areas of fracture fatigue and wear.

Download or read book An Approach to the Fatigue Analysis of Vertical Axis Wind Turbine Blades written by Paul S. Veers and published by . This book was released on 1981 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A General Method for Fatigue Analysis of Vertical Axis Wind Turbine Blades written by Paul S. Veers and published by . This book was released on 1983 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Genossenschaft des Buchgewerbes und verwandter Berufszweige written by and published by . This book was released on 1929 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Probabilistic Fatigue Methodology and Wind Turbine Reliability written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Wind turbines subjected to highly irregular loadings due to wind, gravity, and gyroscopic effects are especially vulnerable to fatigue damage. The objective of this study is to develop and illustrate methods for the probabilistic analysis and design of fatigue-sensitive wind turbine components. A computer program (CYCLES) that estimates fatigue reliability of structural and mechanical components has been developed. A FORM/SORM analysis is used to compute failure probabilities and importance factors of the random variables. The limit state equation includes uncertainty in environmental loading, gross structural response, and local fatigue properties. Several techniques are shown to better study fatigue loads data. Common one-parameter models, such as the Rayleigh and exponential models are shown to produce dramatically different estimates of load distributions and fatigue damage. Improved fits may be achieved with the two-parameter Weibull model. High b values require better modeling of relatively large stress ranges; this is effectively done by matching at least two moments (Weibull) and better by matching still higher moments. For this purpose, a new, four-moment[open-quotes]generalized Weibull[close-quotes] model is introduced. Load and resistance factor design (LRFD) methodology for design against fatigue is proposed and demonstrated using data from two horizontal-axis wind turbines. To estimate fatigue damage, wind turbine blade loads have been represented by their first three statistical moments across a range of wind conditions. Based on the moments[mu][sub 1][hor-ellipsis][mu][sub 3], new[open-quotes]quadratic Weibull[close-quotes] load distribution models are introduced. The fatigue reliability is found to be notably affected by the choice of load distribution model.

Download or read book Advances in wind turbine blade design and materials written by A.P. Vassilopoulos and published by Elsevier Inc. Chapters. This book was released on 2013-10-31 with total page 55 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fatigue life prediction of wind turbine rotor blades is a very challenging task, as blade failure is led by different failure types that act synergistically. Inherent defects like wrinkles, fiber misalignments and voids, that can be introduced during fabrication, can constitute potential damage initiation points and rapidly develop to failure mechanisms like matrix cracking, transverse-ply cracking, interface cracking, debonding, fiber breakage, etc. Different methods have been established to address this problem, some based on phenomenological and others on actual damage mechanics modeling. This chapter aims to provide an overview of fatigue life modeling and prediction methodologies for the composite materials and structural composite elements that compose a wind turbine rotor blade under complex loading conditions.

Download or read book WISPER and WISPERX written by A. A. ten Have and published by . This book was released on 1992 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Biaxial Dynamic Fatigue Tests of Wind Turbine Blades written by Falko Bürkner and published by Fraunhofer Verlag. This book was released on 2021-04-09 with total page 195 pages. Available in PDF, EPUB and Kindle. Book excerpt: Testing rotor blades of wind turbines is essential to mitigate financial risks caused by serial damages. Present day uniaxial dynamic tests are time consuming and often inaccurate regarding the applied loading. This thesis proposes a faster fatigue test method by loading the two primary directions at the same time. In addition, a more realistic test, compared to uniaxial tests, is accomplished by loading larger areas of the blade cross-sections. To achieve this, an elliptical biaxial dynamic excitation is used. To fulfill the industry requirement for cost effective tests, a relatively simple test setup was developed, still achieving an elliptical dynamic excitation of the rotor blade. Two methods for an accurate determination of the applied loadings for dynamic fatigue tests are described. These calibration tests use easily measured values and simple analysis to achieve accurate test load measurements in a cost-effective way.

Download or read book Fatigue Life Prediction of Composites and Composite Structures written by Anastasios P. Vassilopoulos and published by Elsevier. This book was released on 2010-07-27 with total page 569 pages. Available in PDF, EPUB and Kindle. Book excerpt: The use of composites is growing in structural applications in many industries including aerospace, marine, wind turbine and civil engineering. There are uncertainties about the long term performance of these composites and how they will perform under cyclic fatigue loading. Fatigue life prediction of composites and composite structures provides a comprehensive review of fatigue damage and fatigue life prediction methodologies for composites and how they can be used in practice.After an introductory chapter, Part one reviews developments in ways of modelling composite fatigue life. The second part of the book reviews developments in predicting composite fatigue life under different conditions including constant and variable amplitude loading as well as multiaxial and cyclic loading. Part three then describes applications such as fatigue life prediction of bonded joints and wind turbine rotor blades as well as health monitoring of composite structures.With its distinguished editor and international team of contributors, Fatigue life prediction of composites and composite structures is a standard reference for industry and researchers working with composites and those concerned with the long-term performance and fatigue life of composite components and structures. - Examines past, present and future trends associated with fatigue life prediction of composite materials and structures - Assesses novel computational methods for fatigue life modelling and prediction of composite materials under constant amplitude loading - Specific chapters investigate fatigue life prediction of wind turbine rotor blades and bonded joints in composite structures

Download or read book Approach to the Fatigue Analysis of Vertical axis Wind turbine Blades written by and published by . This book was released on 1981 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A cursory analysis of the stress history of wind turbine blades indicates that a single stress level at each wind speed does not adequately describe the blade stress history. A statistical description is required. Blade stress data collected from the DOE/ALCOA Low Cost experimental turbines indicate that the Rayleigh probability density function adequately describes the distribution of vibratory stresses at each wind speed. The Rayleigh probability density function allows the distribution of vibratory stresses to be described by the RMS of the stress vs. time signal. With the RMS stress level described for all wind speeds, the complete stress history of the turbine blades is known. Miner's linear cumulative damage rule is used as a basis for summing the fatigue damage over all operating conditions. An analytical expression is derived to predict blade fatigue life.

Download or read book Advances in wind turbine blade design and materials written by J.F. Mandell and published by Elsevier Inc. Chapters. This book was released on 2013-10-31 with total page 53 pages. Available in PDF, EPUB and Kindle. Book excerpt: This chapter explores the influence of resin and reinforcing fabric variations on the fatigue sensitivity for a wide range of typical blade laminates reported recently in the SNL/MSU/DOE database. Test results are presented for static and fatigue property variations with resin type, reinforcing fabric construction and weight, fiber content and laminate construction. Critical resin/fabric interactions and damage mechanisms are identified. The effects of resin and fiber type are also explored for material transitions at ply drops, where ply delamination is the dominant damage.

Download or read book Fatigue Life Prediction for Wind Turbines written by TD. Ashwill and published by . This book was released on 1994 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wind turbines are fatigue-critical machines used to produce electrical energy from the wind. These rotating machines are subjected to combinations of wind, gravity, and gyroscopic loadings that are highly irregular in nature. Historical examples of fatigue problems in both research and commercial wind-turbine development are presented. Some example data on wind-turbine environments, loadings, and material properties are also shown. Before a description of how the authors have chosen to attack the cumulative damage assessment, questions are presented for the reader's reflection. The solution technique used by the authors to define the loading spectrum for wind turbines is then presented. Special emphasis is placed on the development of a loading spectrum for use in the fatigue analysis. Less attention is paid to methods of cumulative damage assessment; Miner's rule and constant amplitude S-n data are used. A case study then applies the procedures to an actual wind-turbine blade joint. The wind turbine is the 34-m diameter vertical axis wind turbine (VAWT) erected by Sandia National Laboratories near Bushland, TX. The case study examines parameter sensitivities for realistic uncertainties in inputs defining the turbine environment, stress response, and material properties. The fatigue lifetimes are calculated using a fatigue analysis program, called LIFE2, which was developed at Sandia.

Download or read book Proceedings of the 13th International Conference on Damage Assessment of Structures written by Magd Abdel Wahab and published by Springer. This book was released on 2019-07-04 with total page 957 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains the proceedings of the 13th International Conference on Damage Assessment of Structures DAMAS 2019, 9-10 July 2019, Porto, Portugal. It presents the expertise of scientists and engineers in academia and industry in the field of damage assessment, structural health monitoring and non-destructive evaluation. The proceedings covers all research topics relevant to damage assessment of engineering structures and systems including numerical simulations, signal processing of sensor measurements and theoretical techniques as well as experimental case studies.

Download or read book Advances in wind turbine blade design and materials written by R.P.L. Nijssen and published by Elsevier Inc. Chapters. This book was released on 2013-10-31 with total page 43 pages. Available in PDF, EPUB and Kindle. Book excerpt: Composites have been the material of choice for wind turbine blade construction for several decades. This chapter explains why. It also shows how wind turbine blade materials and our understanding of their fatigue behaviour have developed recently, and the gaps that still exist in the knowledge. The chapter discusses why fatigue is a predominant design driver for wind turbine blades. The main structural elements of the blade (load bearing components and aerodynamic shell) are considered in terms of material and design requirements, and fundamental research questions are addressed. Finally, there is a comment on current and future trends, as well as a list of recommended reading.

Download or read book New Method for Dual Axis Fatigue Testing of Large Wind Turbine Blades Using Resonance Excitation and Spectral Loading Scholar s Choice Edition written by National Renewable Energy Laboratory (Nr and published by Scholar's Choice. This book was released on 2015-02-16 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work has been selected by scholars as being culturally important, and is part of the knowledge base of civilization as we know it. This work was reproduced from the original artifact, and remains as true to the original work as possible. Therefore, you will see the original copyright references, library stamps (as most of these works have been housed in our most important libraries around the world), and other notations in the work. This work is in the public domain in the United States of America, and possibly other nations. Within the United States, you may freely copy and distribute this work, as no entity (individual or corporate) has a copyright on the body of the work.As a reproduction of a historical artifact, this work may contain missing or blurred pages, poor pictures, errant marks, etc. Scholars believe, and we concur, that this work is important enough to be preserved, reproduced, and made generally available to the public. We appreciate your support of the preservation process, and thank you for being an important part of keeping this knowledge alive and relevant.