### Experimental Results
#### 2.3.2 Plates Subjected to Three FSP Impacts  
In the next series of tests, three separate consecutive shots were carried out on each plate. This means that each FSP impacted a plate at rest. Figure 11 represents a plane view of the aluminum plate specimens of configurations 3 and 4 after full perforation by three 7.62 mm and three 12.7 mm FSPs, respectively. The figure also shows the corresponding out-of-plane displacement fields of the performed tests. Each red dot represents the geometrical center of the three impact holes. The numbers 1, 2, and 3 indicate the order of impact of the different FSPs. At first sight, neither small cracks nor petal-like deformations are observed around the impact zones of both configurations. The plates only experienced a small bending deformation in the direction of impact. However, the small displacements of the plate at some distance from the hole  
Figure 10: Major principal strains of points placed on a circle of a given radius (15 mm, 30 mm or 45 mm) from the impact center as a function of their orientation angle for the three tests of configuration 2 and shows the influence of FSP orientation at the moment of impact on the amplitude of the major principal strain. Figure 9: Comparison between the major principal strain fields of 7.62 mm (**left**) and 12.7 mm (**right**) FSP perforation. caused by each FSP impact seem to combine. Indeed, each impact leads to a given plastic out-of-plane displacement. This results in a zone of maximum displacement inside and in the vicinity of the triangle formed by the three impacts. Although the displacements may appear insignificant, they contribute to an overall deformation from the plate's center to the periphery of the impact zone, encompassing the entire triangle formed by the three impacts. Figure 11: Plane view of the different tests of configurations 3 and 4 after full FSP perforation and their corresponding out-of-plane displacement fields. Figure 12 compares the different tests in terms of the out-of-plane displacement history of the geometrical centers of the holes shown in Figure 11.  
Three oscillating parts can be distinguished. Each part corresponds to the plate's response after a single impact. The flat parts, or plateaus, represent the residual plastic deformations either before or after an impact. Configuration 4 shows the largest plastic deformation. This is because the impacts are closer to one another and the center of the plate and because of the use of 12.7 mm FSPs in that configuration. The analysis shows that the out-of-plane displacements due to the projectile impacts depend on the relative impact positions and the distance with respect to the center of the plate. In addition to the out-of-plane displacements, the strains are also computed. The major principal strains are represented in Figure 13 for the third test of configuration 3 and the test of configuration 4. The typical pattern observed for a single impact is still present. However, it can be seen that the typical \"strain patterns\" for each individual impact influence each other. These interactions between the strain patterns of each impact are more important for closer impacts (case of configuration 4). of this blast loading tool has been reported in previous studies [3; 26; 27] and is therefore only briefly described in this section. The experimental setup used to study the dynamic response of the blast-loaded plates is shown in Figure 14. It is located at the test bunker of the Propellant, Explosives and Blast Engineering department (PEBE) of the Royal Military Academy. A 10 g C4 explosive charge was placed at the entrance of the EDST. The EDST was built around a 1200 mm long cylindrical steel tube with a wall thickness of 4.5 mm and an inner diameter of 168.2 mm. Figure 14a shows the EDST installed on a steel frame structure with a controlled height from the ground. The center of the tube was set at the same height as the plate center's point. A high-frequency pressure sensor [28] was mounted at the exit of the inner wall of the tube.