## 2 Experimental Investigations and Data Acquisition
### Laboratory Experiments on a Full-Scale Test Specim  
Deliberate and targeted damage to the tendons of an operating wind turbine is most certainly irresponsible. However, such damage events are essential for the intended analysis. For this reason, a full-scale test specimen was set up in the _Otto-Mohr-Laboratory_at _TU Dresden_ (see Figure 5 and [36]). The aim was to replicate the structural conditions as accurately as possible. Therefore, a full-scale test specimen was set up.  
A 12.0 m long and 4.1 m wide frame was designed, which was pre-stressed with four _SUSPA-Draft EX30_ tendons. The tendons consist of a total of 30 parallel, individual wires, which are guided through a PE duct grouted with grease. The selected tendon lengths reflect technically feasible dimensions and allow an adequate survey of the attenuation properties along the tendons. Four novel anchorages were provided and embedded in a crossbeam to replicate the foundation adequately. The transition piece was also recreated using a massive crossbeam, which was cast onto a 5 cm thick steel plate and thus reflected the connection to the steel tower and the local structural conditions of the wind turbine. The center-to- center distance of the tendons is 0.9 m. This is about twice the distance at the transition piece and about 0.1 m less than the distance at the foundation.  
All 30 wires were separated one after the other on each tendon of the test frame. To depict different scenarios, the cutting position varied along the tendon length. A total of 120 wire break events were artificially induced as part of the research project. This article focuses exclusively on the 30 wire break events of one specific tendon and the associated sensor arrangement.  
An overview of the sensor arrangement can be found in Figures 5 (right) and 6. The frame was equipped with a total of 24 sensors, of which only the 16 sensors shown in these figures were analyzed. The other sensors are irrelevant for this analysis due to their hardware configuration. Sensor 1 was positioned on the steel plate of the novel anchorage (Figure 6, right). Sensors 2 to 8 were positioned along the tendon at equal distances of one meter using special mounting clamps. The cutting position, where the wire breaks were generated, was between sensors 1 and 2. These sensors are at distances of 0.65 m and 1.00 m closest to the breaking position of the wires. Additional sensors were attached to the crossbeams of the frame in the axes of the tendons. On the crossbeam representing the foundation (Figure 6, right), sensors 13 to 16 were centrally located between the threaded rods of the anchorage. On the other crossbeam, which represented the transition piece, the tendons were anchored to the steel plate located behind the crossbeam. The sensors 21 to 24 were attached adjacent to each tendon (Figure 6, left).  
Figure 5: Photo (**left**) and schematic (**right**) of the test frame consisting of four pre-stressed _SUSPA-Draft EX30_ tendons. These tendons are anchored on one end to the novel anchorage with the foundation crossbeam and on the other end to a 5 cm thick steel plate at the transition piece crossbeam. Experimental setup with sensor positions, channel numbers (box) and cutting position at the tendon under investigation.  
_VS30_ sensors from _Vallen Systeme GmbH_ were used, as had already been used for the operational measurements. The sampling rate was set at 10 MHz. The sensors on the crossbeams were operated with 0 dB preamplifiers. Different preamplifier settings were applied to the tendons' sensors and the anchoring plate (sensor 1-8), either with 0 dB, \(-20\) dB, or \(-40\) dB. To ensure the comparability of all sensor data, the attenuated signals were converted to a preamplification of 0 dB.