In this study, the deceleration of non-deforming projectiles with different nose shapes during penetration into semi-infinite concrete and aluminum targets was investigated using hydrocode simulations. The aim of the work was to review the assumption of constant deceleration, which underlies several empirical or semi-analytical models, and to provide a foundation for future models. The results of the performed simulations show that the deceleration of projectiles fundamentally varies as a function of the instantaneous velocity and the impact velocity and is thus generally not constant. This is particularly true for concrete and is therefore likely to apply to similar geomaterials. In the case of aluminum, the assumption of constant deceleration is, to some extent, reasonable within specific velocity regimes.
Shaped-charge warheads constitute a distinctive, highly effective, and comparatively inexpensive class of munition, employed principally in rocket-propelled grenades (RPGs) and in a range of civil applications such as perforating rock formations in mining, oil-well perforation, and other geotechnical operations. The armor-piercing capability of an RPG derives from the explosively driven formation of an elongated metallic jet that attains hypervelocity. The hydrodynamic penetration mechanism of this elongated, semi-solid metallic jet is highly complex and remains incompletely understood: both the advancing jet and the target — rolled homogeneous armor (RHA) steel — respond hydrodynamically, that is, as though they were incompressible fluids, even though both remain nominally solid throughout the event. The present study seeks to defeat penetration by the elongated jet of an RPG warhead by means of an add-on layered composite armor system that consists of layers of boron carbide along with alümina spherical balls and highly lubricating very fine silicate powders. A series of controlled detonation and terminal-ballistic experiments was performed on explosive munitions in order to elucidate the microstructural evolution and properties of the copper jet. The water-jet-like metallic streams were successfully deflected, arrested, captured, and contained within the interior layers of a highly effective add-on composite armor configuration. The findings demonstrate that the lethality of this weapon can be substantially reduced by redirecting and bending its linear elongation and its penetration path.
The proposed study investigates the application of physics-informed oversampling in machine-learning models to approximate ballistic curves and ballistic limit velocities that represent the resistance of targets made from S355 steel under impacts of 7.62 × 51 mm P80 (0.308 Win) small-calibre projectiles. Through a detailed terminal ballistic experimental investigation, we determined ballistic limit velocities and corresponding limit curves for four target thicknesses: 20 mm, 16 mm, 8 mm, and 5 mm. The experimental results for the four impact configurations were used to validate the finite element analysis, resulting in an additional set of 11 ballistic limit curves and ballistic limit velocities for a total of 15 configurations of S355 steel plates, with thicknesses ranging from 4 mm to 18 mm. Finite element simulations complemented the experimental data and further characterised the effects of varying plate thickness on protection level. Several machine-learning approaches, including deep neural networks (DNN), Random Forests (RF), Support Vector Machines (SVM), and XGBoost (XGB), were trained on a part of the data. Their efficiency and accuracy in predicting experimentally identified ballistic limit features were then evaluated for the remaining data subset. By leveraging available data and incorporating specific physical mechanisms into machine-learning algorithms, the study analyses the applicability and limitations of these approaches.
Explosive incidents, whether accidental or intentional, pose significant threats to buildings, critical infrastructure, and urban environments. Understanding the evolution of blast-resilient design research is therefore essential to developing safer, more resilient built environments. This study presents a bibliometric and thematic analysis of blast-resilient design research, based on 1982 publications indexed in the Scopus database between 2000 and 2026. Bibliometric analyses were conducted in VOSviewer to examine publication trends, leading journals, country collaboration networks, subject-area distributions, keyword co-occurrence, and co-citation relationships, complemented by a thematic interpretation of the identified research domains. The results reveal a substantial increase in publication activity, particularly after 2015, reflecting the growing importance of blast resilience in structural safety research. The findings further demonstrate that the field remains predominantly engineering-oriented, with comparatively limited contributions from architecture and urban planning. Overlay visualisation indicates a shift in focus from conventional topics such as reinforced-concrete behaviour and progressive collapse towards numerical simulation, optimisation, machine learning, and advanced protective materials. Overall, the study identifies significant disciplinary fragmentation while highlighting emerging opportunities for interdisciplinary collaboration. By integrating bibliometric mapping with thematic analysis, this research provides a comprehensive overview of the current knowledge structure and offers an evidence-based foundation for future interdisciplinary research and blast-resilient design practices.
Underground industrial service tunnels, protective access passages and utility corridors can transmit explosion-generated pressure waves after an external or near-portal event. This study integrates reduced-scale rectangular tunnel evidence, archived LS-DYNA ALE modelling information and tunnel-network geometry observations from an archived source programme into a validation-bounded loss-prevention assessment. The source programme included a 30 cm x 30 cm steel tunnel, C4 charges of 100-350 g, a 60 cm external stand-off and internal gauge locations at L/D = 0.07, 1.00, 3.00 and 5.67. The archived numerical workflow used C4 JWL modelling, a null-material air domain and Eulerian-Lagrangian coupling. The new contribution is not a new blast-test series or a newly executed numerical campaign. It is an evidence-controlled reanalysis that (i) defines four interpretation tiers, (ii) extracts a case-specific T-junction branch-to-main local peak-overpressure indicator, (iii) consolidates geometry mechanisms into a screening map, and (iv) converts these findings into an action-oriented loss-prevention workflow. Because complete raw pressure-time histories, model decks and repeat-test statistics are not available in a unified archive, the manuscript does not claim design-grade validation. The evidence tiers are calibration check, trend-level support, ratio-level warning and geometry-risk flag. The reanalysis identifies where simplified straight-tunnel attenuation assumptions are insufficient. A recovered equal-section T-junction dataset gives a branch-to-main local peak-overpressure indicator of approximately 0.53. L-bends, open chambers and closed chambers are treated respectively as reflection-concentration zones, expansion/discharge features and recompression-risk spaces, but without universal design coefficients. Three engineering deductions follow from the reanalysis: branch-ratio dispersion must be retained rather than collapsed into a deterministic reduction coefficient; sequential features can compound branch loading and recompression risk; and the assigned evidence tier determines whether preliminary screening, rerun, pressure-time validation or layout redesign is required. The workflow helps engineers prioritise CFD/ALE reruns, pressure-time validation and layout redesign in underground loss-prevention planning while clearly separating screening-level interpretation from design-grade extrapolation.
