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Structural Testing Laboratory

Photo of NREL's Wind Research User Facility. Shown in front are several test bays that protect proprietary information while companies disassemble turbines to analyze, test, and modify individual components.

NREL's Structural Testing Laboratory includes office space for industry researchers, houses experimental laboratories, computer facilities, space for assembling turbines, components, and blades for testing. Credit: Patrick Corkery.

NREL's Structural Testing Laboratory at the National Wind Technology Center (NWTC) provides office space for industry researchers, experimental laboratories, computer facilities for analytical work, and space for assembling components and turbines for atmospheric testing. The facility also houses two blade stands equipped with overhead cranes and servo-hydraulic systems, control rooms, a high bay, and several smaller test bays that protect proprietary information while companies disassemble turbines to analyze, test, and modify individual components. In the high bay, NWTC researchers conduct a full range of structural evaluations on turbine blades, including ultimate static-strength, fatigue, vibration, and nondestructive tests. The IUF and NREL's expertise help industry partners verify and improve new blade designs, analyze blade structural properties, and improve their manufacturing processes.

As wind turbines grow in size and their blades become longer and more flexible, it becomes more difficult to test the blades for endurance. At the same time, test methods developed for smaller blades have become more expensive and less effective.

To test the new, larger blades, NREL installed a larger blade test stand capable of testing blades up to 50 m in length. Watch the video below to see NREL's testing capabilities in action.

With NREL's help, various fatigue and static tests can be conducted including:

Fort Felker, center director at the NWTC, discusses NREL's state-of-the-art structural testing capabilities and shows a flapwise and edgewise blade test in progress. Text version.

Blade Fatigue Testing

  • Three independent test cells
  • Dynamic root moment capacity to 13.6 MN-m
  • Testing for blades to 50 m in length (two testing facility for blades greater than 50 m in length are available in Massachusetts and Texas)
  • Conventional forced-hydraulic loading
    • Single-axis
    • Dual-axis
  • NREL-developed linear resonant testing
    • Single-axis
    • Dual-axis resonant

Blade Static Testing

  • Three independent test cells
  • Static root moment capacity to 16.7 MN-m
  • Variable loading configurations
    • 5 or more independent static-load stations
    • Whiffle-tree crane loading.
    • Structural Testing Laboratory 35-ton bridge crane.

Wind Technology Testing Center

The Wind Technology Testing Center (WTTC) is the nation's newest blade testing facility. The length of turbine blades has grown to capture more energy — four times more energy is captured with each doubling of blade length.

A cooperative research and development agreement (CRADA) was formed between NREL and the Massachusetts Clean Energy Center (MASSCEC) to produce the nation’s largest wind turbine blade testing facility, which will run tests on wind turbine blades longer than 50 meters.

NWTC researchers assisted MASSCEC with specifications for the new facility and provided NREL staff to assist in the design and operation of the facility. In addition, the NWTC is in the process of designing and procuring the static and fatigue blade test systems for WTTC based on designs developed for blade testing at the NWTC. Static tests pull a blade in one direction to find its breaking point while fatigue tests simulate wear and tear on the blade, similar to repeatedly bending a paperclip back and forth.

By the end of 2010, completion of the long industrial type building at WTTC will provide the nation’s wind turbine manufacturers with commercial blade certification and reliability testing. The facility will be capable of testing several blades simultaneously. WTTC’s location at an existing deep water port facilitates blade transport.