Analysis of Fatigue Loads of Wind Turbine Blades Subject to Cold Weather Conditions Using a Finite Element Model

Author(s):  
Patricio Lillo ◽  
Curran Crawford
Author(s):  
Jeffrey Bennett ◽  
Robert Bitsche ◽  
Kim Branner ◽  
Taeseong Kim

In this paper a quick method for modeling composite wind turbine blades is developed for aeroelastic simulations and finite element analyses. The method reduces the time to model a wind turbine blade by automating the creation of a shell finite element model and running it through a cross-sectional analysis tool in order to obtain cross-sectional properties for the aeroelastic simulations. The method utilizes detailed user inputs of the structural layup and aerodynamic profile including ply thickness, orientation, material properties and airfoils to create the models. After the process is complete the user has two models of the same blade, one for performing a structural finite element model analysis and one for aeroelastic simulations. Here, the method is implemented and applied to reverse engineer a structural layup for the NREL 5MW reference blade. The model is verified by comparing natural frequencies to the reference blade. Further, the application to aeroelastic and structural evaluations is demonstrated. Aeroelastic analyses are performed, and predicted fatigue loads are presented. Extreme loads from the aeroelastic simulations are extracted and applied onto the blade for a structural evaluation of the blade strength. Results show that the structural properties and natural frequencies of the developed 5MW blade match well with the reference blade, however the structural analysis found excessive strain at 16% span in the spare caps that would cause the blade to fail.


Author(s):  
Anil K. Sahoo ◽  
Utsa Majumder ◽  
Michael W. Nielsen ◽  
Jesper H. Garm

This research work summarizes the study of the structural analysis of shear webs (present in wind turbine blades, sometimes also called as spars) with holes. The webs are sandwich composite structures which are supposed to carry the shear loads coming from the wind pressure and the holes are necessary for non-structural requirements of the wind turbine. The shear webs are strong structures and it is tough to test them to failure in the lab. Hence a structural representative component with lesser dimensions has been tested in the lab to accommodate the capability of the test machines. However, this component test results cannot be directly used in the wind turbine blade structural verification as the web size is much larger in real life. A finite element model is developed to simulate the test specimen and its failure behavior. The concept in this modelling approach is to prepare a digital copy of the actual specimen which will follow the same load-displacement behavior and can predict the same failure as seen in the test coupon. The finite element model is verified for failure using known failure criteria for composite sandwich structures as well as with analytical calculations. This makes sure that the finite element model is a good ‘digital twin’ and simulates the test component behavior one to one. Later, this finite element model is extended to the size of the actual web structure (a family of FE models with different dimensions) to scale up the failure prediction to actual stiffness level.


2021 ◽  
Vol 7 (1) ◽  
Author(s):  
K. Pugh ◽  
M. M. Stack

AbstractErosion rates of wind turbine blades are not constant, and they depend on many external factors including meteorological differences relating to global weather patterns. In order to track the degradation of the turbine blades, it is important to analyse the distribution and change in weather conditions across the country. This case study addresses rainfall in Western Europe using the UK and Ireland data to create a relationship between the erosion rate of wind turbine blades and rainfall for both countries. In order to match the appropriate erosion data to the meteorological data, 2 months of the annual rainfall were chosen, and the differences were analysed. The month of highest rain, January and month of least rain, May were selected for the study. The two variables were then combined with other data including hailstorm events and locations of wind turbine farms to create a general overview of erosion with relation to wind turbine blades.


2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Yiping Shen ◽  
Zhijun Zhu ◽  
Songlai Wang ◽  
Gang Wang

Tapered thin-walled structures have been widely used in wind turbine and rotor blade. In this paper, a spectral finite element model is developed to investigate tapered thin-walled beam structures, in which torsion related warping effect is included. First, a set of fully coupled governing equations are derived using Hamilton’s principle to account for axial, bending, and torsion motion. Then, the differential transform method (DTM) is applied to obtain the semianalytical solutions in order to formulate the spectral finite element. Finally, numerical simulations are conducted for tapered thin-walled wind turbine rotor blades and validated by the ANSYS. Modal frequency results agree well with the ANSYS predictions, in which approximate 30,000 shell elements were used. In the SFEM, one single spectral finite element is needed to perform such calculations because the interpolation functions are deduced from the exact semianalytical solutions. Coupled axial-bending-torsion mode shapes are obtained as well. In summary, the proposed spectral finite element model is able to accurately and efficiently to perform the modal analysis for tapered thin-walled rotor blades. These modal frequency and mode shape results are important to carry out design and performance evaluation of the tapered thin-walled structures.


Author(s):  
Prenil Poulose ◽  
Zhong Hu

Strength evaluation and failure prediction on a modern composite wind turbine blade have been conducted using finite element analysis. A 3-dimensional finite element model has been developed. Stresses and deflections in the blade under extreme storm conditions have been investigated for different materials. The conventional wood design turbine blade has been compared with the advanced E-glass fiber and Carbon epoxy composite blades. Strength has been analyzed and compared for blades with different laminated layer stacking sequences and fiber orientations for a composite material. Safety design and failure prediction have been conducted based on the different failure criteria. The simulation error estimation has been evaluated. Simulation results have shown that finite element analysis is crucial for designing and optimizing composite wind turbine blades.


2018 ◽  
Vol 42 (5) ◽  
pp. 467-482 ◽  
Author(s):  
Damien Caous ◽  
Nicolas Lavauzelle ◽  
Julien Valette ◽  
Jean-Christophe Wahl

It is common to dissociate load computation from structural analysis when carrying out a numerical assessment of a wind turbine blade. Loads are usually computed using a multiphysics and multibody beam finite element model of the whole turbine, whereas detailed structural analysis is managed using shell finite element models. This raises the issue of the application of the loads extracted from the beam finite element model at one node for each section and transposed into the shell finite element model. After presenting the methods found in the literature, a new method is proposed. This takes into account the physical consistency of loads: aerodynamic loads are applied as pressure on the blade surface, and inertial loads are applied as body loads. Corrections imposed by pressure and body load computation in order to match loads from the beam finite element model are proposed and a comparison with two other methods is discussed.


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