Probability distributions of wind turbine loads are estimated from limited data. The impact of different models on fatigue damage is shown. Common one-parameter probability models, such as the Rayleigh and exponential, are found to give significantly different estimates of load distributions and damage. Greatest differences occur in materials with relatively high values of the S–N exponent b, such as composites. In such cases more accurate damage estimates are found by matching at least two moments of the load data (Weibull model), or still higher moments as well. For this purpose, a new, four-moment “generalized Weibull” model is introduced. For edgewise loads it appears a notable improvement over the basic Weibull model, while it supports the Weibull model in the flapwise case. Uncertainty in damage estimates is also quantified, along with the implied data needs.

Coleman, C., and B. McNiff, 1989, “Final Report: Dynamic response testing of the northwind 100 wind turbine,” Subcontractor Report, Solar Energy Research Institute, Golden, CO.
Committee on Fatigue and Fracture Reliability
, “
Fatigue reliability: Review papers 1-4
J. Struc. Div.
, ASCE, Vol.
(STl), pp.
Jackson, K., 1992, “Deriving fatigue design loads from field test data,” Proc., WindPower 92, AWEA.
Mandell, J. F., Reed, R. M., Samborsky, D. D., and Pan, Q., 1993, “Fatigue performance of wind turbine blade composite materials,” Proc., 13th Wind Energy Symp., ASME, SED-14.
Sutherland, H. J., 1993, “Effect of flap and edgewise bending moment phase relationships on the fatigue loads of a typical HAWT blade,” Proc., 13th Wind Energy Symp., ASME, SED-14.
Sutherland, H. J., and Veers, P. S., 1995, “Fatigue analysis of WECS components using the generalized Weibull model,” Proc., Wind Energy 1995, ASME, SED-16, pp. 83–90.
Sutherland, H. J., and Butterfield, S., 1994, “A summary of the workshop on fatigue life methodologies for wind turbines,” Proc., WindPower 94, AWEA.
Thresher, R. W., Hock, S. M., and Osgood, R. M., 1991, “Data record length effects on rainflow analysis,” Proc., 11th Wind Energy Symp., ASME, SED-12.
VanDenAvyle, J. A., and Sutherland, H. J., 1987, “Fatigue characterization of a VAWT blade material,” Proc., 8th Wind Energy Symp., ASME, SED-9.
Winterstein, S. R., Lange, C. H., and Kumar, S., 1994, “FITTING; A subroutine to fit four moment probability distributions to data,” Rept. RMS-14, Rel. Marine Struc. Prog., Civil Engineering Department, Stanford University, Stanford, CA.
This content is only available via PDF.
You do not currently have access to this content.