Blade Test Center A/S (BLAEST) - full-scale test of wind turbine blades up to 85 meters

FAQ

• What is a static load test?
  Static tests are carried out as a multipoint load application in vertical direction or in other angles as the customer may require. BLAEST uses a mechanical load system which introduces loads in multiple points simultaneously. The load introduction system works with very small deviations between the individual load points and can complete a static test within few minutes. Data are recorded with a sample rate of up to 250 Hz.
• What is a fatigue test?
  Fatigue load blade tests are performed to determine inherent fatigue properties of a blade, predicting the long-term performance during the designed blade lifespan. The reported data enables certifying bodies to compare measured data to the calculated data of the design criteria. Thus full-scale blade fatigue tests are often an essential part of the approval process.  Fatigue tests may be performed in different ways.

  Edgewise fatigue load testing is normally performed in horizontal orientation and excitations are forced by rotating eccentric masses. For smaller blades, fatigue testing can be executed by using rotating eccentric masses as well. Mainly for larger blades, BLAEST has two types of exciters mounted on the floor: An electric driven exciter with rotating masses, mounted on a seesaw. Furthermore, BLAEST has a newly developed lightweight electrically driven exciter with a pushrod connection to the blade.

• What is modal analysis?
  Modal analysis is the process of determining the modal parameters, which are then sufficient for formulating a mathematical dynamic model. Modal analysis can be accomplished through experimental techniques. It is the most common method for characterization of the dynamic properties of a mechanical system.

  The free dynamic response of the wind turbine blade may be reduced to a discrete set of modes. The modal parameters are: 

  • the modal frequency 
  • the modal damping 
  • the mode shape.