Wind turbine blade with coupling device designed to automatically disengage actuator

1 . A test arrangement for fatigue testing a wind turbine blade, comprising:

a fixing device, wherein a first section of the wind turbine blade is attached to the fixing device; and

an excitation device, wherein a second section of the wind turbine blade is attached to the excitation device, the excitation device comprising an actuator and a coupling device that couples the second section to the actuator in an engaged state, allowing the actuator to exert a force in at least one direction on the second section;

wherein the coupling device is designed to automatically disengage, therefore decoupling the actuator from the second section, when a disengagement condition is met, and to automatically return to the engaged state, when an engagement condition is met during an operation of the excitation device;

wherein the coupling device comprises a wheel driven by the actuator and a contact element that contacts the wheel in the engaged state and that is attached to the second section.

2 . The test arrangement according to claim 1 wherein a fulfilment of the disengagement condition and/or of the engagement condition correlates to a phase of an oscillation of the second section and/or to a deflection of the second section.

3 . The test arrangement according to claim 1 , wherein the coupling device comprises a stop, formed as a further wheel, that is spaced apart from the wheel in a radial direction, wherein the contact element contacts both the wheel and the stop in the engaged state.

4 . The test arrangement according to claim 1 , wherein the contact element is a flat plate, wherein a connection between the contact element and the second section is formed by or comprises a connection segment having a maximum diameter that is smaller than a thickness of the flat plate.

5 . The test arrangement according to claim 4 , wherein the connection segment is formed by a string or wire.

6 . The test arrangement according to claim 4 , wherein the connection segment extends at an angle to a vertical direction.

7 . The test arrangement according to claim 1 , wherein the coupling device comprises a further actuator that is designed and arranged to move the wheel between a contact position for contacting the contact element in the engaged state of the coupling device and a disengagement position, in which the wheel is decoupled from the contact element.

8 . The test arrangement according to claim 7 , wherein that the excitation device comprises an additional wheel, that is driven by an additional actuator, and an additional further actuator that is designed and arranged to move the additional wheel between a contact position for contacting the contact element and a disengagement position, in which the additional wheel is decoupled from the coupling device, wherein a control unit is designed to control the further actuator and the additional further actuator in such a way that at a given time during the operation of the excitation device the wheel is only in the contact position when the additional wheel is in the disengagement position and vice versa.

9 . The test arrangement according to claim 8 , wherein the actuator and/or the additional actuator is a rotating motor and/or an electromechanical actuator.

10 . The test arrangement according to claim 1 , wherein a ballast is attached to the contact element via a further connection segment, via a string or wire.

11 . The test arrangement according to claim 1 , wherein the actuator is controlled by the or a control unit, wherein the control unit is configured to invert a movement direction of the actuator when a reversal condition is met, wherein the coupling device is configured to automatically disengage prior to an inversion of the movement direction in at least one operational state of the excitation device.

12 . The test arrangement according to claim 11 , wherein a fulfilment of the reversal condition depends on measurement data provided by at least one sensor that is designed and arranged to monitor a position and/or a movement of at least one component of the contact elementor of the coupling device in the at least one operational state of the excitation device.

13 . A method for fatigue testing a wind turbine blade, wherein

attaching a first section of the wind turbine blade to a fixing device,

attaching a second section of the wind turbine blade to an excitation device, and

utilizing an actuator of the excitation device to excite an oscillation of the wind turbine

blade, wherein the excitation device comprises a coupling device that couples the second

section to the actuator in an engaged state, allowing the actuator to exert a force in at least

one direction on the second section,

wherein the coupling device automatically disengages, therefore decoupling the actuator from the second section, when a disengagement condition is met, and automatically returns to the engaged state, when an engagement condition is met during an operation of the excitation device;

wherein the coupling device comprises a wheel driven by the actuator and a contact element that contacts the wheel in the engaged state and that is attached to the second section.

14 . A test arrangement for fatigue testing a wind turbine blade, comprising:

a fixing device, wherein a first section of the wind turbine blade is attached to the fixing device; and

an excitation device, wherein a second section of the wind turbine blade is attached to the excitation device, the excitation device comprising an actuator and a coupling device that couples the second section to the actuator in an engaged state, allowing the actuator to exert a force in at least one direction on the second section;

wherein the coupling device is designed to automatically disengage, therefore decoupling the actuator from the second section, when a disengagement condition is met, and to automatically return to the engaged state, when an engagement condition is met during an operation of the excitation device;

wherein the actuator is controlled by the or a control unit, wherein the control unit is configured to invert a movement direction of the actuator when a reversal condition is met, wherein the coupling device is configured to automatically disengage prior to an inversion of the movement direction in at least one operational state of the excitation device.