Generolo Jono Žemaičio Lietuvos karo akademija

The rapid spread of unmanned aerial vehicles and loitering munitions has created a new class of threats for critical infrastructure, especially for facilities that depend on uninterrupted operation and contain exposed roof and wall assemblies. In such an environment, the design of protective systems can no longer focus only on conventional lateral threats or on isolated single-impact scenarios. Instead, it must address repeated fragmentation exposure, localized cumulative damage, and the need to preserve functionality after attack. This paper develops a standalone conference contribution based primarily on the ballistic material evaluation presented in Chapter 5 of the source study. The text focuses on the structural characteristics, test response, and engineering applicability of rigid glass-fiber-reinforced polymer (GFRP) panels and flexible Twaron T730 aramid systems for infrastructure protection. Two GFRP panels with nominal thicknesses of 12.2 mm and 14 mm were evaluated under ballistic loading, while rear-face deformation was measured by laser profilometry and internal damage was assessed using digital radiography. In parallel, a multilayer Twaron T730 aramid configuration was used as a comparative flexible barrier system. The results confirm that rigid GFRP panels provide stable mechanical resistance, controlled rear-face deformation, and a low probability of catastrophic penetration under the tested conditions. The radiographic evaluation further shows that internal damage zones can significantly exceed visibly damaged areas, highlighting the importance of non-destructive inspection for reliable post-impact assessment. The aramid system demonstrates favorable energy absorption under moderate impact loading, but it also reaches its limits under repeated higher-energy events. Based on the combined results, the paper argues that rigid composite panels are the most suitable primary protective element for large-area infrastructure applications, while aramid systems are best employed as supplementary internal layers or as part of a hybrid configuration. The findings are discussed in relation to roof protection, multi-hit resistance, modular retrofitting, and the practical design of protective envelopes for critical infrastructure exposed to fragmentation hazards.

This paper addresses the problem of experimental reproducibility in the study of blast effects during explosive tactical breaching. In real conditions, breaching charges exhibit significant variability, which complicates the comparison of measured pressure responses and limits systematic research. The study investigates whether real breaching charges can be replaced by standardized spherical charges with an equivalent TNT effect. Experimental measurements were carried out in a training facility using pressure sensors, and the results were evaluated in terms of peak overpressure, impulse, and pressure-time history. The findings indicate that standardized charges provide comparable blast characteristics, with differences within acceptable limits. The proposed approach enables more reproducible experiments and creates a basis for further research on structural resilience and human exposure to repeated blast loading.