scholarly journals Reconstructing Stress Resultants in Wind Turbine Towers Based on Strain Measurements

2021 ◽  
pp. 224-235
Author(s):  
Marko Kinne ◽  
Ronald Schneider ◽  
Sebastian Thöns
Keyword(s):  
Wind Turbine ◽  
Wind Waves ◽  
Support Structures ◽  
Strain Measurements ◽  
Cyclic Stresses ◽  
Waves And Currents ◽  
Wind Turbine Towers ◽  
The Individual ◽  
Cyclic Demand ◽  
Dynamic Phenomena

AbstractSupport structures of offshore wind turbines are subject to cyclic stresses generated by different time-variant random loadings such as wind, waves, and currents in combination with the excitation by the rotor. In the design phase, the cyclic demand on wind turbine support structure is calculated and forecasted with semi or fully probabilistic engineering models. In some cases, additional cyclic stresses may be induced by construction deviations, unbalanced rotor masses and structural dynamic phenomena such as, for example, the Sommerfeld effect. Both, the significant uncertainties in the design and a validation of absence of unforeseen adverse dynamic phenomena necessitate the employment of measurement systems on the support structures. The quality of the measurements of the cyclic demand on the support structures depends on (a) the precision of the measurement system consisting of sensors, amplifier and data normalization and (b) algorithms for analyzing and converting data to structural health information. This paper presents the probabilistic modelling and analysis of uncertainties in strain measurements performed for the purposes of reconstructing stress resultants in wind turbine towers. It is shown how the uncertainties in the strain measurements affect the uncertainty in the individual components of the reconstructed forces and moments. The analysis identifies the components of the vector of stress resultants that can be reconstructed with sufficient precision.

COASTAL ENGINEERING 2000

2000 ◽  
Vol 1 (27) ◽  
Author(s):  
Billy L. Edge
Keyword(s):  
Wind Waves ◽  
Storm Surges ◽  
Coastal Engineering ◽  
Coastal Processes ◽  
Coastal Structures ◽  
Wave Groups ◽  
Coastal Waves ◽  
Waves And Currents ◽  
The Individual ◽  
Engineering Projects

*** Available Only Through ASCE *** http://ascelibrary.aip.org/browse/asce/vol_title.jsp?scode=C This Proceedings contains more than 300 papers presented at the 27th International Conference on Coastal Engineering, which was held in Sydney, Australia, 16-21 July 2000. The Proceedings is divided into five parts: characteristics of coastal waves and currents; long period waves, storm surges and wave groups; coastal structures; coastal processes and sediment transport; and coastal, estuarine, and environmental problems. The individual papers include such topics as the effects of wind, waves, storms, and currents as well as the study of sedimentation, erosion, and beach nourishment. Special emphasis is given to case studies of completed engineering projects. With the inclusion of both theoretical and practical information, these papers provide the civil engineer and professionals in related fields with a broad range of information on coastal engineering and coastal processes affecting design and operations in the coastal zone.This Proceedings contains more than 300 papers presented at the 27th International Conference on Coastal Engineering, which was held in Sydney, Australia, 16-21 July 2000. The Proceedings is divided into five parts: characteristics of coastal waves and currents; long period waves, storm surges and wave groups; coastal structures; coastal processes and sediment transport; and coastal, estuarine, and environmental problems. The individual papers include such topics as the effects of wind, waves, storms, and currents as well as the study of sedimentation, erosion, and beach nourishment. Special emphasis is given to case studies of completed engineering projects. With the inclusion of both theoretical and practical information, these papers provide the civil engineer and professionals in related fields with a broad range of information on coastal engineering and coastal processes affecting design and operations in the coastal zone.This Proceedings contains more than 300 papers presented at the 27th International Conference on Coastal Engineering, which was held in Sydney, Australia, 16-21 July 2000. The Proceedings is divided into five parts: characteristics of coastal waves and currents; long period waves, storm surges and wave groups; coastal structures; coastal processes and sediment transport; and coastal, estuarine, and environmental problems. The individual papers include such topics as the effects of wind, waves, storms, and currents as well as the study of sedimentation, erosion, and beach nourishment. Special emphasis is given to case studies of completed engineering projects. With the inclusion of both theoretical and practical information, these papers provide the civil engineer and professionals in related fields with a broad range of information on coastal engineering and coastal processes affecting design and operations in the coastal zone. *********** This volume was originally published by ASCE. ASCE database link, for record and hard copy purchase: http://cedb.asce.org/cgi/WWWdisplay.cgi?126156

scholarly journals Recent Advances in Vibration Control Methods for Wind Turbine Towers

Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7536
Author(s):  
Georgios Malliotakis ◽  
Panagiotis Alevras ◽  
Charalampos Baniotopoulos
Keyword(s):  
Vibration Control ◽  
Wind Turbine ◽  
Structural Reliability ◽  
State Of The Art ◽  
Wind Waves ◽  
Control Methods ◽  
Environmental Loads ◽  
Recent Advances ◽  
Wind Turbine Towers ◽  
The Impact

Wind power is a substantial resource to assist global efforts on the decarbonization of energy. The drive to increase capacity has led to ever-increasing blade tip heights and lightweight, slender towers. These structures are subject to a variety of environmental loads that give rise to vibrations with potentially catastrophic consequences, making the mitigation of the tower’s structural vibrations an important factor for low maintenance requirements and reduced damage risk. Recent advances in the most important vibration control methods for wind turbine towers are presented in this paper, exploring the impact of the installation environment harshness on the performance of state-of-the-art devices. An overview of the typical structural characteristics of a modern wind turbine tower is followed by a discussion of typical damages and their link to known collapse cases. Furthermore, the vibration properties of towers in harsh multi-hazard environments are presented and the typical design options are discussed. A comprehensive review of the most promising passive, active, and semi-active vibration control methods is conducted, focusing on recent advances around novel concepts and analyses of their performance under multiple environmental loads, including wind, waves, currents, and seismic excitations. The review highlights the benefits of installing structural systems in reducing the vibrational load of towers and therefore increasing their structural reliability and resilience to extreme events. It is also found that the stochastic nature of the typical tower loads remains a key issue for the design and the performance of the state-of-the-art vibration control methods.

scholarly journals Experimental and simulation-based analysis of asymmetrical spherical roller bearings as main bearings for wind turbines

2021 ◽  
Author(s):  
Amin Loriemi ◽  
Georg Jacobs ◽  
Sebastian Reisch ◽  
Dennis Bosse ◽  
Tim Schröder
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Measurement Data ◽  
Contact Angles ◽  
Suspension System ◽  
Roller Bearings ◽  
Axial Forces ◽  
Wind Turbine System ◽  
Bearing Life ◽  
The Individual

AbstractSymmetrical spherical roller bearings (SSRB) used as main bearings for wind turbines are known for their high load carrying capacity. Nevertheless, even designed after state-of-the-art guidelines premature failures of this bearing type occur. One promising solution to overcome this problem are asymmetrical spherical roller bearings (ASRB). Using ASRB the contact angles of the two bearing rows can be adjusted individually to the load situation occurring during operation. In this study the differences between symmetrical and asymmetrical spherical roller bearings are analyzed using the finite element method (FEM). Therefore, FEM models for a three point suspension system of a wind turbine including both bearings types are developed. These FEM models are validated with measurement data gained at a full-size wind turbine system test bench. Taking into account the design loads of the investigated wind turbine it is shown that the use of an ASRB leads to a more uniform load distribution on the individual bearing rows. Considering fatigue-induced damage an increase of the bearing life by 62% can be achieved. Regarding interactions with other components of the rotor suspension system it can be stated that the transfer of axial forces into the gearbox is decreased significantly.

Wind load response of offshore wind turbine towers with fixed monopile platform

2016 ◽  
Vol 158 ◽  
pp. 122-138 ◽  
Author(s):  
M. Feyzollahzadeh ◽  
M.J. Mahmoodi ◽  
S.M. Yadavar-Nikravesh ◽  
J. Jamali
Keyword(s):  
Wind Turbine ◽  
Wind Load ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Load Response ◽  
Wind Turbine Towers

Strain Measurement by X-ray Diffraction Methods

1949 ◽  
Vol 1 (3) ◽  
pp. 211-224
Author(s):  
G. B. Greenough
Keyword(s):  
Strain Measurement ◽  
Plastic Anisotropy ◽  
Stress And Strain ◽  
Routine Method ◽  
X Ray Diffraction ◽  
Strain Measurements ◽  
X Ray ◽  
The Past ◽  
Polycrystalline Metals ◽  
The Individual

SummaryMany papers have been written on the measurement of strain by X-ray diffraction methods and on the interpretation of these strains in terms of stresses. Whereas, during the past few years, the experimental methods of determining the strains have. remained largely unchanged, research has shown that the older techniques for calculating stresses from strains are not always valid.In this paper an attempt is made to describe some of the principles of strain measurement by X-ray diffraction methods to those who are unfamiliar with the methods. The types of stress and strain systems which may exist in polycrystalline metals are then considered, particular attention being paid to the effect of the elastic and plastic anisotropy of the individual crystals. Some indication is given as to how the earlier methods of interpreting X-ray strain measurements should be modified, but no rigid routine method is proposed for use in a general case.

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