## 3 Methodology of Wire Rope Research
### The Steel Wire Rope Diagnostic Research Results  
Experimental tests were performed after applying tension to the rope, corresponding to 90% of static nominal load. Vibration was applied from an electrodynamic mini-vibrator in the transverse direction to the rope axis. The exciting vibration amplitude is adjusted so that, during the shift of frequency, it remains permanent. Measurement of the vibration amplitudes of the rope and broken wires was taken simultaneously when the rope was excited on remote places from contactless sensors. Rope diameters for the experimental research were taken from industrial needs: 3.92, 3.96 and 4.0 mm diameter ropes are widely used in elevators due to the small diameter and small bending radius. Small differences of broken wire vibrating amplitudes bring advantages for the method; diagnosed ropes of close diameter use the same settings. Diameters of the ropes outside diameter range should be set for different diagnostic frequencies. Tension of the entire rope fragment will alter the natural frequency of the rope itself; the natural frequency changes of broken wires can be neglected. Broken wires are not influenced by tension, as they have free ends. Damping effects in the rope are very large, therefore, decaying of the rope vibrations are significant, but this does not affect the essence of the diagnostic method. The implemented method measures only the relative vibration of a broken wire with respect to the surface of the rope. Here, it is important to obtain the relative vibrations; otherwise, only rope surface vibrations will be measured. The obtained graphs of results for the 1350 mm rope are presented in Figure 4.  
Practical implementation of this method is in the tension station of the elevator between two pulleys. Extra fixture for the rope is placed there and the test is performed as on a test rig. After the test, the next part of rope is tested, previously sliding to next fragment between the pulleys. Test in the field conditions: wire fragment rate is 1300 mm (for practical range of the overall tensed rope frequency when rope is from 3.8 to 6 mm); 1500 mm when length is from 6 to 12 mm. The minimal radius tested was limited by practical dimensions used in elevator, typically 4-6 mm. From experimental results, it is evident that the broken wires are successfully excited, therefore, their amplitudes are significantly higher than the rope surface. Using various diameters and lengths of rope, in the range of frequencies from 115 Hz to 182 Hz, diagnostic features became efficient. Graphically efficient areas of vibration diagnostics are presented in Figure 4. Of course, various lengthsof broken wires have different natural frequencies, but they are in a technically convenient frequency range. Wires with 8-10 mm lengths have maximum amplitudes that occur at a frequency of 160 Hz. In the case the exciting frequency equals 160 Hz and the rope length and diameter are 1350 mm and 3.92 mm, respectively, a 10 mm broken wire generates an amplitude of 11.6 mm. All the data correspond to the case when broken wires have higher amplitude and there is a possibility to detect the existence of such a wire. The experimental data presented in Table 1 show a sample of the overall data. All experimental data can be found in Appendix A (Table A1). The experimental test proved the frequencies over 258 Hz had caused amplitudes of broken wire vibrations equal to the entire rope vibration amplitudes. Therefore, there is no need to continue raising the frequency for ropes of the tested diameter. The most promising is the frequency range between 115 Hz and 182 Hz; as the variable dynamic response amplitude of the rope, the broken wires are sensitive to this frequency range. \begin{table}