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Title: Fabrication of low-cost Mod-0A wood-composite wind-turbine blades

Technical Report ·
DOI:https://doi.org/10.2172/6218609· OSTI ID:6218609

A contract was awarded to Gougeon Brothers, Inc., by NASA Lewis Research Center, under Department of Energy sponsorship, for the development and fabrication of two 60-foot, low-cost wood composite blades for service on a 200-kW Mod-0A wind turbine machine. The contractural effort consisted of blade design and analysis and fabrication phases. This report provides a brief summary of the design and analysis phase, and an indepth review of the blade fabrication phase. The wood composite blades were fabricated by using epoxy resin-bonded laminates of Douglas fir veneers for the leading edge spar sections and honeycomb-cored birch plywood panels for the blade trailing edge or afterbody sections. The blade was joined to the wind turbine hub assembly by epoxy resin-bonded steel load takeoff studs. The wood composite blades were installed in the newest Mod-0A wind turbine test facility at Kukuku, Hawaii called Makini Huila (wind wheel) by the Hawaiians. The wood composite blades have successfully completed high power (average of 150 kW) operations for an 18-month period (nearly 8000 h) prior to replacement with another set of wood composite blades. The original set of blades were taken out of service because of the failure of the shank on one stud. An inspection of the blades at NASA Lewis showed that the shank failure was caused by a high stress concentration at a corrosion pit on the shank fillet radius which resulted in fatigue stresses in excess of the endurance limit. The remainder of the blade, including the embedded portion of the fractured stud, and the entire wood structure was found to be in excellent condition. All of the remaining studs, with the exception of four studs that showed an onset of corrosion, were also in excellent condition. The failed stud, as well as four of the corroded studs were successfully replaced with new studs. The blade is currently in a service-ready condition.

Research Organization:
NASA Lewis Research Center, Cleveland, OH (United States); Gougeon Brothers, Bay City, MI (USA)
DOE Contract Number:
AI01-76ET20320
OSTI ID:
6218609
Report Number(s):
DOE/NASA/20320-45; NASA-TM-83323; ON: DE83012967
Country of Publication:
United States
Language:
English