Environmental Engineering Reference
In-Depth Information
Fatigue Testing of Wind Turbine Blades
Current methods for designing, conducting, and analyzing the results of fatigue tests of
wind turbine blades are described by White [2004]. Much of the following discussion con-
tains information from this reference. Readers are referred to White's comprehensive report
for details not only on fatigue testing but also on the following supporting topics:
-- Historical review of blade fatigue testing
-- Wind turbine blade loads, deflections, natural frequencies, and phase angles
-- Fatigue damage analysis, and
-- Controller design of a multi-function fatigue testing machine
While dynamic computer models using programs such as
ADAMS
and
FAST
[Kelley
1997] have now been developed to simulate the real-time response of a wind turbine blade to
wind conditions over its lifetime, there is still a need to physically test blades under controlled
conditions. By applying a schedule of fatigue loads to a full-size blade it is possible to
-- Verify the design strength, stiffness, and natural frequencies as predicted using a
finite- element model
(FEM) of the blade
-- Identify potential manufacturing defects, and
-- Validate blade fatigue endurance in months instead of decades
Current Major Fatigue Test Facilities for Wind Turbine Blades
At this time there are four national laboratories worldwide that maintain major facilities
for performing static and fatigue tests of both small and large wind turbine blades, as fol-
lows:
RISO National Laboratories (RISO) in Denmark
RISO operates under the Danish Ministry of Science, Technology, and Innovation. Stat-
ic, fatigue, and modal tests of wind turbine blades are conducted at the
Sparkuer Blade Test
Centre
in Roskilde.
Centre for Renewable Energy Sources (CRES) in Greece
CRES operates under the Greek Ministry of Development. Facilities located in Attiki
are capable of testing wind turbine blades up to 25 m in length.
Wind Turbine Materials and Constructions Knowledge Centre (WMC) in the Netherlands
A modern facility opened in 2003, WMC is a joint project between
Delft University
and
the
Energy Research Centre of the Netherlands
(ECN). It has the capability of testing blades
up to 60 m in length.
National Renewable Energy Laboratory (NREL) in the United States
NREL, a laboratory operated for the U.S. Department of Energy, is responsible for wind
turbine blade testing at its
National Wind Technology Center
(NWTC) in Golden, Colorado.
More than 100 blades have been tested at the NWTC facility, which is unique in the U.S.
Most of these tests have been conducted for commercial wind turbine manufacturers under
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