Probability assessment of static overload in wind turbine blade bearings considering turbulence, design, and manufacturing variability

Abstract

This study presents a probability assessment of static overload of a double-row, four-point contact ball blade bearing under ultimate limit state conditions. The methodology follows structural reliability principles applied to this specific limit state. The National Renewable Energy Laboratory 5 MW reference wind turbine is selected for the study, and a Monte Carlo simulation is used to assess static overload reliability and estimate the probability of failure. The sensitivity of the probability of failure to uncertainties in turbulence intensity, material properties, and bearing dimensions is evaluated. Within the bounds examined, the blade bearing conformity has the largest effect on the probability of failure, and ball diameter is next. The probability of damage for case-study wind sites around the world is assessed, and it is observed that the probability of failure is higher in some cases than for wind conditions described by IEC 61400-1.