## 3 Numerical Research
### Numerical Results  
Damage caused by the strikers with various geometries at different instances of the simulation (up to reach the maximum depth of the penetration) is shown in Figures 14-15. Each reinforcing layer is marked by a different color. The cross sections of damaged areas owing to the impact of various strikers are shown in Figure 7. The direction of the impact is marked using a white arrow. Figure 6: Numerical research: (**a**) schematic diagram, (**b**) physical model. Figure 7: Cross sections of damaged areas caused by (**a**) conical striker, (**b**) hemispherical striker, (**c**) blunt striker, and (**d**) ogival striker. The numerical results have shown that the largest damages (Figure 7a) occurred when a conical striker was used. The smallest damage occurred in the case of a blunt striker (Figure 7c), which corresponds to the experimental results. The area of damage for each striker geometry is different. The damage caused by impact of the striker with a conical end (Figure 7a) is characterized by the formation of a narrowing taper. In each subsequent damaged layer, the number of degraded elements decreased to form a characteristic cone. These damages are the largest among the analyzed cases. The sharp end of the conical striker penetrating successive layers of material caused rapid damage to the individual elements in subsequent reinforcing layers, which contributed to the weakening of the entire structure. The damage caused by the hemispherical striker (Figure 7b) was less extensive compared with the damage caused by the conical striker. The resulting damage does not form a characteristic cone. The largest damages were observed in the first four layers of reinforcement. The elements that were not deleted are arranged in a chaotic manner. It can be observed that the elements in the second layer of reinforcement in the impact area are not completely destroyed, which can be interpreted as the fiber compression inside the formed crater (as mentioned in the chapter about experimental research). The other two damaged layers (5 and 6) were minimally damaged--individual elements were deleted. The blunt striker did not cause any visible damage in the reinforcement material (Figure 7c). The ogival striker caused the most damage (Figure 7d) in the first two layers of the material. Penetration of subsequent layers was characterized by the removal of the same number of finite elements until the striker energy was too low to damage the next layer. The last of the damaged layers degraded in the form of individual elements. The colored map of Tresca stress presented in Figure 8 showed that the primary yarns (at the direction defined as a fiber direction--X and Y axis) carried the largest load. The secondary yarns were much less loaded. This conclusion was confirmed in the work of [16]. In addition to the analysis of destruction, which was performed based on the Figure 7c, the value of Tresca stresses shown in Figure 8 suggests that the matrix could be damaged. As shown in Table 2, the tensile strength of the matrix is 75-85 MPa. Tresca stress at the edge of impacting striker (on the first layer of reinforcement) was much higher (92.5-110 MPa). This analysis suggests that the matrix could be damaged, as in the case of the experimental research (matrix cracking). The average diameter of this area was 7.5 mm. Figure 8: Colored map of Tresca equivalent stress on the first layer of reinforcement in case of blunt striker impact. Table 6 shows the diameters of the cavities and depth of the penetration of the damages created by the impact of strikers with different geometries. The measurement of cavity diameters was done between the nodes of the elements at the first layer, which were not deleted after impact. The biggest damage in the first layer of reinforcing material was observed for the case in which the conical striker hits the composite. The second largest diameter of the damaged area was observed for the case in which a hemispherical striker was used.