**5. Experimental Validation**

## *5.1. Test Bench*

The experimental bench consists of a crankcase connected with the electric motor of 10 KW maximum power through a shaft and two rolling bearings: healthy (6206 ball bearing) and degraded (N.206.E. G15 roller bearing), Figure 8. A hydraulic jack via steel cable was used to vary loads on the shaft (Figure 8a). The motor has rotational speed controlled by variable speed drive. The whole device was built to a concrete structure to isolate it from the low frequencies generated by the external environment. A piezoelectric sensor was placed radially on the bearing, considered as the best measuring point. The data were collected with a sampling frequency of 51,200 Hz. Eight defects on the outer ring of the roller bearing were created with an electro pen. The defects were measured using a paste mark "plastiform", Table 9. The resulting profile was characterized as roughness, with a Taylor-Hobson subtronic 3P profilometer (Figure 8b). For the nine states of the defect (one healthy and eight defect sizes), 10 randomly operating conditions were applied among 5 loads ranging from 100 to 220 daN, with a 30 daN step, and 5 rotation speed varies ranging from 1405 to 1560 rpm with a 50 rpm step. The number of combinations was 90 (*k* = 90). For each combination 8 signals were collected (*n* = 8) with 12,800 samples. The total database was made of 720 signals.

**a**  **b** 

**Figure 8.** (**a**) Test bench (**b**) profilometer with PlastiformTM paste.



AOC-OPTICS method was applied. The inputs were Δ*t* = 1 (*de f ault value*), *Tini* = 10 and *n* = 8. Thus, at each iteration *k*, 8 new signals integrated the algorithm. Eighty signals initiated the monitoring process.
