## 3 Results and Discussion
### Influence of Projectile Material
#### 3.1.3 Damage Morphology  
The triaxial braided composite target plate suffers no visible damage on the impact surface when impacted with a gelatin projectile at an impact velocity of 169 m/s. Figure 10 shows the morphology of the damage suffered by the target after the impact of the gelatin projectile at an impact velocity of 213 m/s. The impact surface reveals no obvious deformation or fiber breakage. However, delamination, matrix cracking, and a small amount of fiber breakage appears in the through-thickness direction of the target. The damage to the exit surface of the target plate is indicative of matrix cracking at a distance from the impact point. The boundary conditions of the composite panel affect the dynamic response and deformation features of the target panel, correspondingly resulting in different damage patterns. Therefore, if clamping in all edges, it is possible to obtain the results of perforation by the gelatin projectile, as illustrated in literature [24]. Although the gelatin projectile did not perforate the target, the existing test results have fully proved that the energy absorption of the composite material panel is much higher when impacted with soft gelatin projectile than that with the hard metal and composite material. The main reason for this result is that, due to the fluid behavior of the gelatin projectile during impact, the contact area with the target plate during impact is much larger than the impact area of the metal and composite blade-like projectiles. The target plate undergoes an overall large bending deformation, which dissipates more impact energy. Consequently, the impact energy is more evenly distributed over the entire target plate. Figure 11a shows the morphology of the damage suffered by the 2D triaxial braided composite target in the Ti-1 test due to the impact of a titanium-alloy projectile at an impact velocity of 105 m/s. A significant shear fracture rectangular opening appears on the incident surface, with an area and shape that are substantially the same as the cross-sectional area of the titanium-alloy projectile, which was quite small and thin. On the exit surface of the target appears an elliptically bulged area of damage. The damaged area shows obvious damage modes such as fiber breakage, matrix cracking, or delamination, as shown in Figure 12. Figure 11b shows the damage of a 2D triaxial braided composite after impact by a titanium-alloy projectile at an impact velocity of 160 m/s (Ti-3 test). Given that the blade projectile has a certain yaw angle when it exits, an open-type tear occurs on the incident surface of the projectile. The damage on the backside of the target plate is more serious: the damage area is about twice that of the incident-projectile surface, and obvious fiber breakage and delamination have occurred. The test results show that, for the titanium-alloy projectile perforating the 2D triaxial braided composite target plate, the damage form and damage mode of the target plate are basically the same (i.e., fiber shear fracture and local matrix cracks on the impact surface, and bulged deformation with fiber breakage, fiber pull-out, and delamination). The damage area is smaller. Figure 10: Damage to 2D triaxial braided composite target plate caused by impact of gelatin probe. (Gelatin-2 test, 213 m/s). In rebound cases, the typical damage caused by the CFRP projectile on the front side of the target is relatively similar. As shown in Figure 12(a), projectile impact creates a rectangular sunken area of the same size as the cross-section of the projectile. The sunken area is shallow, with no visible cracking or damage. No visible matrix cracking, bending deformation, or serious delamination appears on the exit surface of the triaxial braided target. The target plate remains basically intact with no visible damage. Figure 12(b) shows the damage to a triaxial braided composite target after perforation by a CFRP blade-like projectile with an impact velocity of 157 m/s.