## 3 Results and Discussion
### Fragmentation Resistance Test Results
The relationships between the above mentioned mechanisms and the ballistic performance of the materials used for soft ballistic inserts are not yet fully described as they depend on a number of variables related to the type of materials used to produce the ballistic package and the bullet and/or fragment used. With reference to the research carried out herein, it is possible to confirm the occurrence of mechanisms, i.e., the tearing and extension of fibers and yarn of soft ballistic insert (Figure 5c,d). In turn, crushing of ceramic elements and partial delamination of the external elastomeric coating were observed for HSC composites. However, no processes related to melting or rupture of the elastomer have been reported during the fragmentation resistance tests, which is probably related to the significant thermal stability of the silicones used (Figure 5a,b). The mechanism of rupture of ceramic elements and their influence on ballistic resistance was analyzed in previous studies. [PERSON] et al. [60] pointed out that the role of ceramics is to blunt the bullet's blade, break it into smaller fragments, and absorb some of its energy through fracture. He also stated  
Figure 5: Components of the HSC composite after the ballistic test: (**a**) ceramics tiles—view from the impact side of the fragment; (**b**) silicone outer layer—view from the outlet side of the fragment; (**c**) Twaron®CT612 soft ballistic armor—view from the impact side of the fragment; (**d**) Twaron®CT612 soft ballistic armor—view from the outlet side of the fragment. that the role of a composite made of fibrous material such as UHMWPE or para-aramid pre-impregnate, to which a ceramic layer is attached, is to stop fragments of the bullet core by elastic deformation and absorption of kinetic energy. Energy absorption takes place through combinations of deformation, fiber extension, and composite delamination [61]. When a bullet hits, the ceramic layer is exposed to very strong compressive stress. A stress wave travels through the material and when it reaches the adhesive layer, it is reflected as a tensile stress wave. The interaction of these two waves leads to cracking and destruction of the armor frontal ceramic cover. However, before this happens, the tip of the bullet is blunted or broken into smaller pieces. Therefore, it is important that the front layer of ceramics is as hard as possible [61; 62]. Moreover, in the construction of the layered armor, a very important role is played by the adhesive layer between the ceramics and the fibrous substrate, which must be strong enough to ensure that after a hit, the undamaged areas of the ceramics layer and the substrate remain bound together [60]. The process of bullet penetration into the ceramic armor was also presented by [PERSON] [63]. He described this process as a four-stage one with the individual stages:  
1. bullet and armor collision;
2. initial penetration of the bullet into the armor at a constant speed;
3. braking the bullet by the inertial and strength forces of the armor material;
4. final crater formation. In the first stage of the bullet's collision with the armor, the wave that occurs at the moment of impact propagates from the tip of the bullet to its end, generating stresses exceeding the static limit of material strength. At this stage, the tip of the bullet is plastically deformed and the shock wave moving to the end of the bullet creates a stress that causes axial cracking at its edges. As the deformation wave moves along the bullet, cracks appear. On the other hand, due to the impact, the armor creates tension and pressure, which causes the bullet's armor materials to become liquid and create a crater. At the second stage, the bullet penetrates the armor at constant speed. The crater is enlarged by the flow of the liquid phases of the bullet and armor on the sides. The back of the bullet moves faster than its tip, which then erodes. At the third stage, the high pressure field disappears and the speed of the bullet penetrating the armor is gradually lost.