Method and testing device for testing rotor blades

A method for testing a rotor blade of a wind turbine, wherein a setpoint bending moment distribution is predetermined, comprising at least the steps:

• clamping the rotor blade in a clamping device so that a longitudinal axis of the rotor blade extends from a clamping point of the rotor blade,
• attaching one or more load frames to the rotor blade,
• providing at least two active load-introducing means which each engage on one of the load frames, wherein a first of the at least two active load-introducing means is set up for introducing load in a pivot direction of the rotor blade and a second of the at least two active load-introducing means is set up for introducing load in an impact direction of the rotor blade,
• providing at least one passive load-introducing means engaging one of said load frames, wherein for a system comprising said rotor blade and said at least one passive load-introducing means, a system natural frequency for the pivot direction and/or for the impact direction is changed by said at least one passive load-introducing means,
• a cyclic introduction of load is effected by the at least two active load-introducing means, wherein a load introduction frequency of the first active load-introducing means and a load introduction frequency of the second active load-introducing means are selected such that the ratio thereof is rational, and wherein
• the load frames and the at least two active load-introducing means and the at least one passive load-introducing means are arranged at previously determined positions which are selected in such a way that a bending moment distribution introduced during cyclic load introduction does not fall below the setpoint bending moment distribution and does not exceed it by more than 20%.