###### Abstract
In other words, delamination occurs because the strength of the matrix material is much less than the strength of the reinforcing material. Therefore, the largest part of the impact energy is absorbed as a result of fiber destruction [16; 22]. The process of destroying the energy absorbing panel made of laminate can be divided into two phases. In the first phase, a high-speed striker hits the panel, causing fiber shear and matrix cracking. Primary yarns carry the highest loads. Secondary yarns are much less stressed. In the second phase, as the successive penetration of reinforcement layers progresses, the smaller and smaller energy of the striker is distributed over an ever larger surface, and finally it becomes insufficient to break the fibers in subsequent reinforcing layers [13; 16]. The remains of the impact energy initiates the matrix delamination process. The reinforcement fibers in deeper layers are stretched under the influence of the impact energy concentration [12; 16; 23]. The microscopic image of damage in the composite with the hybrid reinforcement that was used in the conducted research is shown in Figure 1. The presented sample was hit by the hemispherical striker. The jagged fragments of the fibers at the side opposite to the impact side are the result of the cutting process. In Figure 1, it can be seen that the aramid fibers are deformed, broken, and sheared as a result of the striker impact. Around the impact area, accumulation of the damaged reinforcing layers could also be observed. The carbon fibers located between the aramid fibers owing to the high Young's modulus were deformed elastically and rebounded the striker. The total energy at impact is the sum of the remaining kinetic energy of the striker and the energy absorbed by the composite panel. The total energy during impact could be divided at the energy of the moving striker, energy absorbed by shear plugging, energy absorbed by deformation of secondary yarns, energy absorbed by tensile failure of primary yarns, energy absorbed by delamination, energy absorbed by matrix cracking, and energy absorbed by friction [22]. Considering energy absorption, the most commonly used reinforced material is aramid fibers [16]. These fibers can absorb a large amount of the impact energy before their breaking. Furthermore, aramid fibers are more elastic than, for example, carbon fibers [24]. They are characterized by high rigidity and orientation, and they are connected to each other by strong, dense hydrogen bonds [25]. They have a good strength to density ratio (specific strength). Strength expressed in this way for Kevlar(r) fibers is greater; that is, five times greater than steel [16]. The tensile curves of aramid fibers,similar to glass and graphite fibers, are approximately linear to break. Aramid fibers have a density 43% lower than that of glass fibers. Because of that, aramid fibers are particularly attractive for the production of many composites [25]. Energy-absorbing panels built using aramid fibers provide excellent protection against pistol bullets, revolver bullets, or fragmenting debris. Aramid fibers are one of the most important materials used for the production of energy absorbing panels [16]. However, in the application of energy absorbing panels, stiffness is also very important and should be enough high to prevent too much deformation after impact. To minimize that deformation employment of carbon fibers between aramid fibers, reinforcement layers could be a solution. However, carbon fibers have some disadvantages. The first of them is the brittle damage [26] after impact, which can be dangerous for nearby people. It is worth mentioning that the brittle damage in some cases can be desirable, especially during modelling of the separation process [27; 28; 29; 30]. In this case, the process should be designed in such a way that the equivalent stress should exceed the allowable stress that appears in the direct cutting zone. Otherwise, the material being removed would not be separated.