## 5 Results  
### Experimental Results  
In the present work, four experimental tests were carried out; the specimens were named 1, 2, 3, and 4. The test using specimen 1 was discarded. In all tests, the load and displacement were captured. Additionally, in the test using specimen 4, the acoustic emission data were recorded and the results are plotted in Figure 7. All plots use normalized time, \(t_{n}=t/t_{\text{max}}\), where \(t_{\text{max}}\) is the time when the load reaches 100% of its peak value. In Figure 7, for specimen 4, the load vs. normalized time, signal amplitudes, accumulated signals, and AE energy are plotted. The \(b\)-value and DPH index evolution are presented for the information captured with sensor 1 and sensor 2, which were positioned as indicated in Figure 5c. The following are observations about Figure 7:  
1. In Figure 7a, the load vs. normalized time (\(t_{n}\)) results are presented. Only after \(t_{n}\approx 0.55\) does the load start to increase. This occurs because the support was unable to correctly fix the specimen, as the upper supports (labels 2 and 3 in Figure 5a) introduce flexibility to the system. 2. The AE signals from sensors 1 and 2 are presented in Figure 7b. Note the high activity recorded at sensor 2 around the normalized time 0.15, which is due to the movement of the support, which is indicated by label 3 in Figure 5a. Furthermore, more AE emissions can be observed from sensor 2 (\(S_{2}\), right side) than from sensor 1 (\(S_{1}\), left side). This information is consistent with the final configuration presented in Figure 8c, where it is evident that the damage is concentrated on the right side of the specimen. 3. Figure 7c presents the accumulated number of signals and AE energy. Observe that in Figure 7b,c, in \(t_{n}\approx 0.7\), a sequence of signals was captured with both sensors, but these were in greater quantity for sensor 2. This AE activity is probably due to the opening of the crack tip. Figure 6: Peridynamic model details: (**a**) Config. 1; and (**b**) Config. 2. (**c**) Details of the level of discretization and the horizon, \(\delta\). * The evolution of the \(b\)-value is presented in Figure 7d. Note that both sensors indicate a drop in the \(b\)-value only at the end of the test when a collapse is expected. At \(t_{n}\approx 0.15\), the \(b\)-value does not change due to the movement of the supports previously mentioned. * The evolution of the DPH index is presented in dark gray in Figure 7e. The moving average carried out in a window of 175 values is indicated in red in the same figure, and a red diamond indicates the maximum value of the DPH index. This value, as discussed in [26], can be considered a complementary precursor to collapse when an acoustic emission test is carried out. Note that, in the experimental case, the reaction load of the support (indicated by label 3 in Figure 5a) times the prescribed displacement is considered a measure of elastic energy, and from this value the derivative is calculated. * Considering the methodology adopted by [26] and that which was previously described for determining a measure of elastic energy in an experimental test, it is possible to see an abrupt increase in the DPH index at \(t_{n}\approx 0.55\). This is further evidence that the support cannot fix the specimen correctly before \(t_{n}\approx 0.55\). Figure 7: Results for specimen 4 in terms of (**a**) load, (**b**) signal distribution, (**c**) the accumulated number of signals and signal energy, (**d**) the \(b\)-value, and (**e**) DPH index evolution. The horizontal axis is normalized time (\(t_{n}\)). The load and DPH index vs. normalized time are presented in Figure 8, and the final configuration obtained from each test is also indicated. This information is presented for all tests performed for specimens 2, 3, and 4. The following observations can be made about Figure 8:  
1. The initial interval before the upper support actually solicited the specimen (\(t_{n}<0.55\)) was removed from the results presented for specimen 4 in Figure 8.
2.