Alexander JanckerVisiting MSc (@TU-Bergakademie Freiberg, Germany, 2007-2008) – Feasibility Study for Producing Tidal Turbine Blades Made out of Fibre Reinforced Composite Materials with Preliminary Design of the Turbine Blade Layup
MSc Thesis Abstract
This thesis focuses on the evaluation of fibre reinforced polymer (FRP) composite
materials as substitute for stainless steel as structural material in tidal turbine blades.
Reduction in weight and cost as well as an increase in environmental resistance and
service life are the overall objectives. Main concerns are the reliability of FRP in the
marine environment and the proper layup of the laminae in order to obtain a blade
structure, strong and stiff enough to withstand the service loads.
Applications from the wind power and ship building industry are taken into account to
make an appropriate choice of a fibre-matrix combination. A glass fibre / vinyl ester
laminate with a closed cell foam core is most promising for the tidal turbine blades
concerning the environmental degradation, structural reliability and cost. Since the
composite material is build up at the same time as the structure, the manufacturing
process is of importance. For this reason a vacuum bagged technique is preferred, which
allows to produce composite blades with a higher fibre volume fraction resulting in better
mechanical performance, higher resistance against seawater and better fatigue life
The hydrodynamics of the ocean with special behaviours, such as cavitation, internal
waves and stall delay need to be investigated in order to estimate service loads and to be
able to apply factors of safety sufficient for a reliable service life.
The preliminary blade design performed in this thesis made use of conservative safety
factors with a factor of 6 for the loads and 4 for the material. The data were computed
with ExcelBEM and a laminate layup for the blade could be found with a combination of
glass and carbon fibre reinforcement in a vinyl ester matrix. The fibres where aligned in a
0°/45° pattern and 27 to 43 layers of fibre reinforcement along the blade needed to be
applied for structural integrity. Optimisation of the layup sequence has to be performed in
further studies in order to minimize the layers and the need of carbon fibre in the
structure in critical areas.
The literature research performed in this work forms the basis for further research
with the objective of using FRP composite materials as the material of choice for tidal
turbine blades. The preliminary blade design needs to be optimized with measurement
data from the currents and the implementation of accurate models of the unique response
of composite materials into the design code.