From a structural perspective, rotor blades are some of the most critical components of a wind turbine. Fraunhofer IWES is an independent institution which offers structural testing of large-scale rotor blades for both model validation and certification to ensure the blades are reliable. Since 2009, more than 30 blades up to 83 meters in length have been tested.
High degree of confidentiality
The testing methods used at Fraunhofer IWES are accredited in accordance with IEC 61400-23. The institute conducts customized and IEC standard blade tests on one of two separate test stands, located in neighboring halls. This ensures that customers have a high level of access to their blades during testing, while guaranteeing a high degree of confidentiality. The facilities of Fraunhofer IWES are located in close proximity to the harbor in Bremerhaven, providing easy access for delivery of larger rotor blades.
During static testing, loads are applied using hydraulic cylinders and a pulley system. The cylinders are connected to a series of up to eight load frames mounted on the blade. Each load frame is custom designed and built for the specific geometry of the blade being tested. In order to limit forces exerted by the deadweight of the blade, the tests are performed perpendicular to the floor of the test hall. Loads of up to 500 kN can be applied at each load frame. In order to accomodate blades with large deflections under static loading, the larger of the two test blocks can be tilted during static testing. The tests are monitored with the aid of several hundred measuring signals at frequencies of up to 400 Hz, in combination with an optical measurement system that can record three-dimensional deflection of the blade.