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Numerical analysis of connection in wind turbine rotor blade

Ingmarsson, Albin LU (2017) In TVSM-5000 VSM820 20162
Structural Mechanics
Department of Construction Sciences
Abstract
A globally growing population, an increased energy consumption and growing environmental awareness have made the interest for renewable energy sources, such as wind power, higher. As a result of the increased demand the need for new and improved technologies have increased. The energy production of a wind turbine is highly affected by the rotor blade length, which is limited by the massive dead load of the blade. Moreover, rotor blades are expensive and demanding or impossible to transport to inaccessible construction sites. These are some, among many, limitations with wind turbines, which are the premise to a new technology for rotor blades currently being developed. These, innovative wind turbine rotor blades will be longer, cheaper and... (More)
A globally growing population, an increased energy consumption and growing environmental awareness have made the interest for renewable energy sources, such as wind power, higher. As a result of the increased demand the need for new and improved technologies have increased. The energy production of a wind turbine is highly affected by the rotor blade length, which is limited by the massive dead load of the blade. Moreover, rotor blades are expensive and demanding or impossible to transport to inaccessible construction sites. These are some, among many, limitations with wind turbines, which are the premise to a new technology for rotor blades currently being developed. These, innovative wind turbine rotor blades will be longer, cheaper and more mobile than traditional rotor blades.

In a lightweight truss-like structure, e.g. the rotor blade investigated, the structural elements must be designed carefully in general and the connections in particular. One of the connections in the blade, where several of the structural elements are joint, was the focus in this project.

A number of design proposals were evaluated in numerical analyses using finite element methods. Since stress concentrations were developed in the initial design proposal a new design of the connection, where additional structural elements were introduced, was proposed. By introducing a steel pipe and a thin layer of adhesive material, the stresses were distributed more evenly and the loads were transferred more efficient. It was shown that a soft, highly deformable, adhesive is preferable. Moreover, a design of adhesive such that abrupt changes in stiffness are minimised is favourable. This can be achieved by alternating the stiffness over the lap, either by vary the thickness of the layer or by vary the properties of the material. Furthermore, the main beams of the blade should be made of carbon fibre reinforced composite with a layup that was defined.

Moreover, using the designs of the connection element that were considered feasible yet another numerical model was established. This, simplified, model was designed for a defined set up in an upcoming experimental testing. The results from this model can be combined with the results from the experimental testing for proof of concept, to validate the models and to identify sources of errors. (Less)
Popular Abstract (Swedish)
En växande världsbefolkning, politiska regleringar och en strävan att öka andelen energi från förnyelsebara källor har resulterat i att intresset för vindkraftsverk ökat. Winfoor AB utvecklar `Triblade’, en ny teknologi för vindkraftsverksblad som ämnar öka effekten samtidigt som bladen kan göras lättare, billigare och enklare att transportera än dagens vindkrafsverksblad.
Please use this url to cite or link to this publication:
author
Ingmarsson, Albin LU
supervisor
organization
alternative title
Numerisk analys av kopplingselement i vindkraftverksblad
course
VSM820 20162
year
type
H3 - Professional qualifications (4 Years - )
subject
keywords
fibre reinforced composite, truss structure, lightweight, renewable energy, wind turbines, rotor blades, adhesive, finite element method
publication/series
TVSM-5000
report number
TVSM-5220
ISSN
0281-6679
language
English
id
8923281
alternative location
http://www.byggmek.lth.se/english/publications/tvsm-5000-masters-dissertations/
date added to LUP
2017-09-05 14:25:04
date last changed
2017-09-07 14:46:41
@misc{8923281,
  abstract     = {A globally growing population, an increased energy consumption and growing environmental awareness have made the interest for renewable energy sources, such as wind power, higher. As a result of the increased demand the need for new and improved technologies have increased. The energy production of a wind turbine is highly affected by the rotor blade length, which is limited by the massive dead load of the blade. Moreover, rotor blades are expensive and demanding or impossible to transport to inaccessible construction sites. These are some, among many, limitations with wind turbines, which are the premise to a new technology for rotor blades currently being developed. These, innovative wind turbine rotor blades will be longer, cheaper and more mobile than traditional rotor blades.

In a lightweight truss-like structure, e.g. the rotor blade investigated, the structural elements must be designed carefully in general and the connections in particular. One of the connections in the blade, where several of the structural elements are joint, was the focus in this project. 

A number of design proposals were evaluated in numerical analyses using finite element methods. Since stress concentrations were developed in the initial design proposal a new design of the connection, where additional structural elements were introduced, was proposed. By introducing a steel pipe and a thin layer of adhesive material, the stresses were distributed more evenly and the loads were transferred more efficient. It was shown that a soft, highly deformable, adhesive is preferable. Moreover, a design of adhesive such that abrupt changes in stiffness are minimised is favourable. This can be achieved by alternating the stiffness over the lap, either by vary the thickness of the layer or by vary the properties of the material. Furthermore, the main beams of the blade should be made of carbon fibre reinforced composite with a layup that was defined. 

Moreover, using the designs of the connection element that were considered feasible yet another numerical model was established. This, simplified, model was designed for a defined set up in an upcoming experimental testing. The results from this model can be combined with the results from the experimental testing for proof of concept, to validate the models and to identify sources of errors.},
  author       = {Ingmarsson, Albin},
  issn         = {0281-6679},
  keyword      = {fibre reinforced composite,truss structure,lightweight,renewable energy,wind turbines,rotor blades,adhesive,finite element method},
  language     = {eng},
  note         = {Student Paper},
  series       = {TVSM-5000},
  title        = {Numerical analysis of connection in wind turbine rotor blade},
  year         = {2017},
}