| Summary: | The main aim of the present Diploma thesis is the development of a Reference Wind Turbine blade’s
numerical model and the implementation of structural dynamic analyses in order to evaluate the
structural damping effects and the structural integrity of the blade.
During the last decades, the need for renewable energy that has lower environmental impact has
increased exponentially, drawing the attention of the scientific and industrial community towards
the wind energy sector and leading them to put some serious effort on the development of larger
and more efficient wind turbines as also dedicated analysis and design tools.
In this work, some theoretical background related to the wind turbine blades’ structure and
aerodynamic loads is provided, along with a brief presentation of the modelling methods that are
used for the simulation of the blade’s dynamic response. Dedicated wind turbine simulation tools
are examined regarding their framework, as well as the aerodynamic and structural theories and
approaches they employ for the simulation of the entire mechanism. The theoretical part of this
thesis is completed with the review of composites’ loss factors and proportional damping, while the
definition of Rayleigh factors that will be utilized in the numerical models is explained. Before the
description of the blade’s model, a brief review of the two numerical tools (hGAST and DAMPBEAM)
that provide data for the modeling and structural assessment of the component takes place. During
the definition of the wind turbine’s blade model in Abaqus, the CAD model is created, material
properties and composite layups are defined, available dynamic analysis methods and procedures
are examined, load modeling is described, and the meshing strategy is explained. The
implementation of modal analysis provides the eigenfrequencies and eigenmodes of the structure
that are successfully compared with the respective ones from the DAMPBEAM code. For the
damping assessment, various dynamic analyses are performed, where different aerodynamic load cases, damping properties and analysis methods are employed and their results are compared,
extracting important conclusions for the effect of each parameter. Finally, blade’s structural integrity
is evaluated using Tsai-Wu stress-based and maximum strain failure criteria, validating that
structure’s capability of dealing with the load condition of the simulated operation when damping is
taken into consideration.
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