Fatigue testing of a wind turbine blade

A method of fatigue testing a wind turbine blade specimen, the method comprising the steps of:

• providing an apparatus having first and second support assemblies for the specimen;
• holding the specimen with the first and second support assemblies by constraining a first end of the specimen with a first holder of the first support assembly and constraining a second end of the specimen with a second holder of the second support assembly such that the longitudinal direction of the specimen extends between the first and second holders, the first and second support assemblies being arranged such that the first and second holders are each rotatable about an axis extending in a second transverse direction perpendicular to the longitudinal direction of the specimen, the first support assembly being further arranged such that the first holder is further moveable in the longitudinal direction relative to the second holder;
• connecting the specimen to an actuator at a loading position between the first and second holders;
• and
• cyclically deflecting the specimen in a first transverse direction perpendicular to the longitudinal direction of the specimen and to the second transverse direction by generating a cyclical deflection force with the actuator, the first and second support assemblies constraining movement of the holders against movement in the first transverse direction, the deflection of the specimen causing the first and second holders to rotate about the second transverse axis and causing the first holder to move in the longitudinal direction towards to the second holder.

A method of fatigue testing a wind turbine blade specimen, the method comprising the steps of:

• providing first and second support assemblies for the specimen;
• holding the specimen with the first and second support assemblies by holding a first end of the specimen with a first holder of the first support assembly and holding a second end of the specimen with a second holder of the second support assembly such that the longitudinal direction of the specimen extends between the first and second holders;
• connecting the specimen to an actuator at a loading position between the first and second holders;
• attaching at least one additional weight to the specimen to selectively modify a strain profile applied to the blade specimen when it is cyclically deflected in the first transverse direction by the actuator;
• and
• cyclically deflecting the specimen in a first transverse direction perpendicular to the longitudinal direction of the specimen and to the second transverse direction by generating a cyclical deflection force with the actuator, the first and second support assemblies constraining the specimen against movement in the first transverse direction.