Concrete is a multiphase composite material composed of high-strength aggregates, a cement matrix, and the interfacial transition zone (ITZ), whose inherent heterogeneity plays a critical role in its mechanical response. Phenomenological numerical models often assume a homogeneous material formulation, limiting their ability to capture localised failure mechanisms and the composite behaviour. This study presents a mesoscale modelling framework that explicitly represents concrete heterogeneity by incorporating aggregate distribution into finite element meshes generated from design-stage parameters. The approach is applied to ballistic impact scenarios and validated against previously published data by the authors. Finite elements simulations reproduced key experimental trends in stress-strain response, projectile residual velocity and mass loss. Furthermore, the heterogeneous formulation captured effects such as size-dependent behaviour, brittle-to-ductile transition and projectile rotation – which are not available using homogenised models. The framework is scalable and efficient, allowing for parametric studies on aggregate volume fraction, particle size distribution, and aggregate shape. This modelling approach may be used to optimise aggregate parameters during the design stage of a protective structure in response to a specified external threat. • Mesoscale model captured concrete heterogeneity using realistic aggregate geometry. • Framework reproduced size effects and brittle-to-ductile transition in concrete. • Simulations reflect experimental scatter in both material and ballistic tests. • Approach supports aggregate optimisation for protective structures.

Ballistic Impact and Compression after Impact Properties of Fiber Metal Laminates with Different Surface Treatment Methods

A review of ballistic impact behavior and multiscale simulation of composite laminates in wind turbine blades

Experimental and numerical study on oblique ballistic impact performance of CFRP sheets/ultra-thin stainless-steel strip honeycomb sandwich panels

Corrigendum to ’Optimization of steel-UHMWPE multilayer armour under ballistic impact: Experiments and Simulations’

ABSTRACT This study presents a combined experimental and numerical investigation of fused filament fabrication (FFF)‐printed polyether ether ketone (PEEK) plates subjected to quasi‐static and high‐velocity impact loadings. Izod impact, quasi‐static punch‐shear (QS–PS), and high‐velocity projectile impact tests were conducted on specimens with different infill patterns, namely line, grid, cubic, and hexagonal configurations. High‐velocity impact experiments were performed using a two‐stage gas gun at an impact velocity of 100 m/s. Infill architecture influences quasi‐static and low‐rate impact performance. The hexagonal pattern exhibited the highest Izod impact strength (ca. 24 kJ/m 2 ) and punch‐shear strength (ca. 12 MPa), demonstrating improved load distribution and energy absorption capability. Under high‐velocity impact, infill geometry becomes less influential, indicating comparable ballistic responses. This reduced sensitivity to infill pattern is attributed to rapid stress‐wave propagation and extremely short interaction times, which limit progressive deformation within the internal structure. Finite element simulations using a solid PEEK model further support these findings, showing similar stress distributions and penetration behavior across all configurations. The results demonstrate that while infill geometry plays a critical role under quasi‐static loading, its effect diminishes under high‐velocity impact, where the response is predominantly governed by the intrinsic material behavior of PEEK.

Despite their classification as “non-lethal,” Kinetic Energy Non-Lethal Projectiles (KENLPs) still causing fatal injuries, necessitating rigorous biomechanical assessment. Ethical and technical limits of Post Mortem Human Subjects (PMHS) and experimental testing have elevated Finite Element Human Body Models (HBMs) for blunt trauma research. This study develops a two-stage numerical framework for cranial and thoracic injury prediction using LS-DYNA. Firstly, Hybrid III (H3) sub-models are validated against the Ballistics Load Sensing Headform (BLSH) envelope and NATO STANREC 4744 (AEP-99) thorax guidelines using validated KENLPs. Building upon these validations, the second stage proposes the Simplified Head (SH-FEM), featuring a dual-layer scalp and skull architecture, and the Simplified Thorax (STh-FEM)—a three-layer construct comprising muscle, a lung slab, and a central skeletal structure preserving dominant load paths while reducing computational cost. Simulation results indicate peak forces scale nonlinearly from 0.82 to 16.03 kN across 20–80 m⋅s⁻¹, with neck coupling reducing peaks by 20–30%. A velocity inflection at 40 m⋅s⁻¹ marks sub-concussive-to-injurious transitions: <33 m⋅s⁻¹ yields <2.1 kN (insignificant risk), while >55 m⋅s⁻¹ exceeds 7.5 kN (fracture/coma). For thoracic impacts across Cases A–E, VCmax-based AIS ≥ 2 risks vary by model and projectile. In Case E, STh-FEM predicted 46% risk versus H3 at 91%; in Case C, values were 10% and 52%, respectively. Furthermore, STh-FEM overpredicted rigid PVC projectile forces (98% in Case C) but matched the deformable SIR-X projectile (∼8 kN peaks). These simplified models demonstrate controlled, reproducible responses, confirming their feasibility as performant alternatives for rapid KENLPs design screening and safety assessment.

Ballistic and drop-weight impact response of SS304 metal mesh embedded woven flax/hemp fiber hybrid composites

Peridynamic modeling of ballistic impact on metallic-ceramic functionally graded Sandwich plates

As engineering demands intensify, future structural materials have a greater need to be more efficient, performance-tailored, adaptive, and multifunctional, particularly for protective structures in extreme environments. This study explores applying metamaterials and bio-inspired design innovations to create a lightweight acoustic and ballistic barrier composite (LABBCOM) via experimental evaluations of prototypes and conventional baselines. LABBCOM comprises pleated layers of 10 wt.% silica nanoparticle-treated Kevlar fabric with a silicone rubber backing structure integrated with a perforated facesheet for acoustic tunability. An approximate analytical model was developed to predict pleat geometries balancing acoustic and ballistic functionalities. It is found that LABBCOM achieves over double the acoustic absorption compared to mass-equivalent baselines in the 800–1600 Hz range, while providing opportunities for optimizing pleat geometry to address lower frequency bandwidths. In ballistics tests, LABBCOM yielded the only non-penetrative impact result among cases tested, delivering a specific kinetic energy absorption in excess of 25% higher compared to mass-equivalent baselines. Inspecting the failure modes under ballistic impact reveals that the combination of the treated and pleated fabric with rubber backing amplifies energy dissipation without significant weight or volume penalties. Successful transition to applications promises lightweight multifunctional structural barriers for aerospace, defense, infrastructure, and transportation domains, among others.

In the aviation industry the so-called ballistic impact of small accidental or human-made sources on aircraft elements during their service life encompasses several scenarios of practical interest. The experimental assessment of ballistic impact requires dedicated infrastructures (such as the light-gas gun system utilized in this study) and exhibits intrinsic difficulties, mainly concerning the proper acceleration of a projectile and the accurate measurement by a high-speed camera of its (inlet and outlet) velocity. As a first objective, this study aimed at characterizing the dynamic response of fiber metal laminates, manufactured ad hoc by the authors with two different stacking sequences currently not available in commerce. The layups included aluminum 2024 T3 and aramid fiber-reinforced prepregs, leading through specific treatments to excellent specific properties. The collision of the laminate with a 25 g, 9 mm radius steel sphere, traveling at speeds ranging from 90 to 145 m/s, caused a variety of scenarios: partial or complete penetration, with the projectile passing through and continuing its trajectory, remaining stuck in the sample (embedment) or even being bounced back (ricochet). The experimental information led to the estimation, for each typology of sample, of a conventional ballistic limit according to the Lambert-Jonas approximation, as a second objective, these data were utilized to validate an accurate heterogeneous model of the samples developed in the ABAQUS® platform, discretized by finite elements in explicit dynamics and including geometric nonlinearity and contact. We describe plasticity and damage of the metal layers by the Johnson–Cook phenomenological model, progressive failure in the fiber-reinforced plies through a 2D Hashin criterion with damage evolution, and interlaminar debonding at multiple cohesive interfaces governed by the Benzeggagh–Kenane criterion. The outlet speed of the bullet measured during the experiments was retrieved correctly by this model, and a satisfactory agreement of the finite element predictions was found with the deformation patterns and the damage mechanisms identified by post mortem visual inspection. Finally, several discussion points are raised, concerning the robustness of the numerical analyses, the reliability of the constitutive modeling and the identification of the governing parameters.

A critical review on the effect of high-velocity ballistic impact loading on the personal armors used by the soldiers.

Dynamic behaviour of spiderweb-inspired lattice structures for enhanced crashworthiness and energy absorption under impact loading

Numerical simulation and machine learning framework approach for ballistic performance evaluation of aluminium structures

Energy absorption mechanism and cost-benefit assessment of UHMWPE and para-aramid hybrid fabrics for protective structures

Abstract The prevailing global political circumstances and the concomitant increase in security concerns give rise to heightened expectations regarding the building envelope.Transparent areas in façades are essential for daylight entrance and the interaction between the interior and the external environment but represent a risk to building occupants in the case of blast events or attack with firearms. Conventional glazing such as monolithic glazing and laminated safety glass lack resistance to bullet attack due to their brittle fracture behaviour. Glass shows favourable properties in terms of scratch resistance and strength. While the lamination of numerous layers of glass panes provides enhanced resistance against bullet attack, higher dead weights result, necessitating thicker frames and fittings. Due to the higher ductility of polymers, the integration of glass with polymeric glazing material effectively reduces the total dead weight and nominal thickness of security glazing with a resistance against bullet attack. The classification of bullet-resistant glazing is determined in accordance with European standard EN 1063. A test specimen is subjected to a series of three shots fired in a triangular configuration using specified types of weapons and ammunition. The present paper focuses on the topic of bullet resistance by glass panes, plastic sheets and composite panels. In initial experimental tests, monolithic test specimens of annealed glass, toughened safety glass, polycarbonate sheets and polymethylmethacrylate sheets are investigated. The thicknesses of the materials are in a range that will cause a bullet to penetrate. This enables to measure the velocity before and after penetration of the test specimen, as well as to calculate the absorbed energy. Finally, the materials can be characterised in the context of ballistic impact. By recording the mass of the outgoing fragment and the projectile using ultra-high-speed imaging, it is possible to analyse the effect of the materials on velocity reduction. The combination of individual layers with and without lamination by thermoplastic polyurethane interlayers allows for the recommendation of a favourable composition in the cross-section. As result of the research, bullet-resistant glazing with reduced nominal thicknesses can be predicted and processed to slim insulated glazing with high thermal insulation.

ABSTRACT The composite tail drive shaft of the helicopter offers the advantages of high power density, excellent vibration damping characteristics, and superior energy absorption properties. However, it is vulnerable to ballistic impact threats under operational conditions. In this study, ballistic impact tests and finite element modeling were employed to assess and analyze the ballistic impact damage of the composite tail drive shaft. To simulate the intra‐laminar high‐velocity impact damage behavior of composites, a dynamic damage model was developed based on continuum damage mechanics and 3D‐Hashin criterion. The cohesive zone model was used to characterize the inter‐laminar damage initiation and propagation of composites. Additionally, to account for the strengthening effects caused by high strain rates, the strain rate correlation coefficients were introduced to modify the constitutive model. The bullet's residual velocity, the impact process, and the damage morphology of composites obtained from numerical simulations and impact tests demonstrate a high degree of consistency, effectively validating the reliability of the simulation model. Subsequently, using the validated simulation model, the detailed impact damage process and failure characteristics under different typical impact conditions were analyzed and compared. Delamination, matrix tensile damage, and fiber tensile damage were identified as the dominant failure modes, with edge impacts causing more severe damage than central impacts. Furthermore, the effects of offset distance and incident angle on the ballistic impact damage were investigated, revealing significant non‐monotonic effects on material removal volume and the bullet's residual velocity.

Traumatic brain injury (TBI) remains a leading cause of morbidity among military personnel, despite improved personal protective equipment. Although modern combat helmets effectively prevent penetration and skull fractures, their ability to mitigate behind-helmet blunt trauma (BHBT) and primary blast-induced TBI (bTBI) is less clear. This review evaluates combat helmet protection considering biomechanical, medical, and operational evidence. A structured scoping literature review was conducted according to the SANRA framework. Searches were performed in PubMed, Scopus, and SciFinder using combinations of terms related to "combat helmet," "blunt trauma," "ballistic impact," "blast exposure," and "traumatic brain injury." Peer-reviewed studies, experimental reports, and regulatory standards (NIJ, NATO STANAG) were included. Data were synthesized thematically by injury mechanism, protection metric, and helmet design characteristics. Ballistic helmets significantly reduce skull fractures and contusions but provide limited protection against diffuse axonal injury and blast overpressure. Rotational acceleration correlates strongly with predicted strain and mild TBI, yet is not incorporated into current standards. Pad stiffness, fit, and coverage strongly influence both ballistic and blast protection, creating trade-offs between impact absorption and blast under wash. Finite element models and biomarker studies show complementary value but require in vivo validation. Current helmet standards insufficiently address complex threat biomechanics. Future developments should integrate multidimensional metrics, linear and rotational kinematics, strain thresholds, and sensor-derived field data, while balancing tactical functionality with neurobiological protection.

Abstract Despite the excellent mechanical strength of graphene, its inherent brittleness limits its application as an impact-resistant material. To address this limitation, a bilayer system composed of graphene and highly flexible graphene origami (GOri) is investigated using molecular dynamics simulations, with particular emphasis on the effect of stacking order on ballistic impact performance. First, the bimodal load-displacement curves of nanoindentation reveal the superior secondary protective capability of the graphene-on-GOri (rigid-on-flexible) structure, implying that the sub-structure (GOri) can withstand impact even after the super-structure (graphene) fails. Subsequently, it is demonstrated that the ‘hybrid rigid-flexible’ gradient structure significantly enhances the dynamic impact resistance in terms of energy absorption and fracture behavior. Furthermore, based on an analysis of stress wave propagation characteristics and a comparison of projectile penetration response time, the graphene + GOri stacking configuration exhibits exceptional energy delocalization and dissipation behavior, due to the synergistic support provided by the GOri layer through larger out-of-plane deformation, thereby counteracting/delaying the projectile tearing effect on the super-graphene layer. This novel phenomenon is further verified and discussed by comparing the fracture patterns and maximum crack lengths at different impact velocities. This work proposes integrating origami techniques into graphene materials and devises a gradient structure scheme, thus offering new insights for advancing the development of graphene-based impact-resistant materials.

Carbon fiber-reinforced polymer (CFRP) composites exhibit excellent mechanical strength. However, they are susceptible to impact loads due to their low interlaminar fracture toughness, leading to delamination. This work presents an innovative hybrid laminate structure in which carbon and glass fiber yarns are hand-woven alternately over a stainless steel 304 wire mesh (SSWM) and incorporated into a CFRP matrix. In contrast to traditional CFRP mesh-reinforced composites, this design integrates metallic mesh with woven fiber yarns to improve load transmission and damage tolerance. Two different types of laminates, nonwoven (NW) and woven (W), with 90° yarn orientations, were produced using the conventional hand layup method. Low-velocity impact tests were performed at drop heights of 0.5 m and 1 m to assess energy absorption and load-bearing capacity. The results show that woven laminates absorbed more energy and could withstand greater loads when struck by a cylindrical indenter than NW laminates. A ballistic impact investigation was conducted on CFRP laminates of 120 × 120 × 3 mm using hemispherical nose-shaped projectiles. Crucial factors, including impact velocity, residual velocity, damage area, percentage of ballistic resistance, and delamination, were derived from the experimental data. The ballistic impact findings indicate that the residual velocity of the NW composite was 12% lower than that of the woven composite under hemispherical projectile impact, thereby confirming the woven composite's enhanced resistance.