**5. Conclusions**

On the basis of research, it was found the strikers' geometry has a significant e ffect on the damaged microscopic images. The greatest damage was observed for the conical striker (the panel was almost pierced). During the impact, those strikers stuck between the fibers, and pushed them sideways. In the case of such a material penetration mechanism, stretching of the fibers absorbs a smaller part of the impact energy. The fibers in this case are pushed sideways and pressed on the margin of the formed cavity. In the case of a hemispherical striker, much lower damage was observed. The damage caused by this striker was characterized by a large amount of crushed fibers, compressed inside the formed cavity. It is worth noting that the depth of penetration in the case of this type of striker was much smaller than in the case of strikers with the cone-like geometry. The smallest damage was observed for a blunt striker (matrix cracking only). In the analyzed case, there were no damages in the reinforcing layers, but only, as numerical research showed, the integrity of the bonded connection between the reinforcing layers was broken (delamination). The numerical investigations presented that the largest diameters of the delamination areas occur on the side opposite to the impact side. The measurements of the diameters of delamination areas in subsequent layers indicate that these delamination areas form a cone with a base located on the side opposite to the impact side. It was also noticed that the larger delamination areas between the reinforcing layers were between layers where there was smaller damage in the reinforcement. As could be observed in the experimental research, the penetration level in the case of two strikers stops at the depth corresponding to the place when carbon reinforcement layers have been used, which could testify that the use of hybrid structures with carbon and aramid fibers could increase the sti ffness of the panels and increase the puncture resistance of the composite.

**Author Contributions:** Conceptualization, S.S. and M.S.; Formal analysis, S.S.; Funding acquisition, S.D.; Investigation, S.S., M.S., J.K., J.D., and S.D.; Methodology, S.S. and M.S.; Software, S.S.; Supervision, S.D.; Validation, S.S., M.S., J.K., and S.D.; Visualization, S.S.; Writing—original draft, S.S. and J.K.; Writing—review & editing, S.S. and J.K. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was financially supported by statutory funds from the Faculty of Mechanical Engineering of Silesian University of Technology in 2019.

**Acknowledgments:** Calculations were carried out using the computer cluster Ziemowit (https://www.ziemowit. hpc.polsl.pl) funded by the Silesian BIO-FARMA project No. POIG.02.01.00-00-166/08 in the Computational Biology and Bioinformatics Laboratory of the Biotechnology Centre in the Silesian University of Technology.

**Conflicts of Interest:** The authors declare no conflicts of interest.
