Effect of Lightning Strikes on Wind Turbine Blade Life.
Understanding the effects of lightning strikes on wind turbines becomes increasingly
important as the size and rated power of wind turbines increase and as they are placed
in locations where repair is difficult and costly, especially for offshore applications.
When the lightning strikes, it can locally increase material temperature at the strike
zone, inducing high compressive ... read morelocalized strains. The severity of this thermally
induced strain depends on the thermal conductivity of strike zone material and the
surrounding material. The aim of this paper is to develop a methodology to predict blade
residual life after a known number of lightning strikes and to understand the structural
integrity threshold due to such damage. Such data will help the wind community to
develop sensor specification and predictive methods for blade life after each lightning
strike. Thermomechanical stresses and heat transfer cases are used to simulate the
lightning strike blade model and it is analyzed through the use of a commercial finite
element code. A combined thermal and stress analysis of a lightning strike model of
typical wind turbine blade material (including E-glass composite layups) shows that the
fiberglass material immediately surrounding the lightning attachment location becomes
damaged due to plastic deformation. Depending on the magnitude and number of lightning
strikes, the blade has the potential to fail under an extreme static gust load, under
fatigue, or a combination of the two. It is therefore crucial to understand the reduced
material property limits resulting from lighting strikes. It is hoped that this study
will provide a useful guideline for designing lightning protection systems and
predicting blade life, especially for offshore wind turbines where lightning strikes are
statistically more commonplace.
Thesis (M.S.)--Tufts University, 2012.
Submitted to the Dept. of Mechanical Engineering.
Advisor: Behrouz Abedian.
Committee: Behrouz Abedian, Shu Quek, Vincent Manno, and Chandra Yerramalli.
Keyword: Mechanical engineering.read less