Protective lightweight structures can be manufactured from polylactic acid (PLA). Such elements are capable to absorb an impact energy. PLA is also widely used as a honeycomb core material in sandwich panels for aerospace applications. Knowledge of the behavior of PLA plates and shells under high-velocity impact is important for structural design. This paper presents the results of experimental studies of the dynamic characteristics of PLA plates manufactured using additive Fused Deposition Modeling (FDM) technology. The tests were carried out under various impact conditions over a wide range of velocities. Experimental evaluation of the “projectile–PLA target” interaction at different impact velocities made it possible to identify the deformation patterns in the material and the mechanisms of its failure. It was found that PLA behaves primarily as a brittle heterogeneous material. Fracture often occurs due to fragmentation into large pieces with shapes resembling parallelepipeds. These results were used to develop a computational model for the dynamic strength of FDM-manufactured PLA plates, taking into account the layered structure of the material. The proposed model incorporates brittle fracture of the target and the strain-rate sensitivity of the projectile material properties. Based on experimental data, homogenized mechanical characteristics of the FDM-produced material were calibrated. The presented results will be used for computational models of the dynamic strength of three-layer thin-walled structures with honeycomb cores manufactured by FDM additive technologies. The obtained data provide opportunities for optimizing structural components of aerospace vehicles.