Ballistic Impact Research Articles

Photothermally‐Induced Reversible Rigidity of Nacre‐Mimetic Composites Toward Semi‐Active Personal Safeguard

AbstractThe capacity to withstand challenges posed by complex environments is crucial for developing advanced high‐performance protective materials with mechanically adjustable nature. By constructing long‐range hierarchical network of shear‐stiffening gel‐carbon nanotube‐cellulose nanofiber (SCC) embedded within epoxy resin (ER), this work engineers a nacre‐inspired variable‐stiffness SCC‐ER composite (SCCE). Lightweight SCC scaffold attenuates falling impact force from 2.23 to 0.46 kN, and reaches 60 °C within 20 s under 1 sun exposure. Additionally, owing to the rigid ER matrix, SCCE exhibits 4.03 GPa elastic modulus, outperforming numerous conventional engineering materials in puncture resistance. Specific energy absorption of nacre‐mimetic SCCE presents 1.91 MJ m−3 while that of random structural SCCE is only 0.50 MJ m−3. More importantly, SCCE features representative photothermal‐induced reversible rigidity whose storage modulus varies from 9.85 MPa at 30 °C to 11.61 kPa at 116 °C under light stimulation. It also presents shape‐programmability, capable of adhering complex structural surfaces for protection. Eventually, SCCE‐based semi‐active adjustable protectors are constructed that leverage contactless photothermal effect to modulate rigidity. 5 mm‐thick smart SCCE‐protectors resist 163.93 m s−1 ballistic impact while 15‐mm commercial kneepads are penetrated at lower speed of 136.98 m s−1. This bio‐inspired semi‐active strategy proposes a promising avenue for enhancing personal protective equipment.

Influence of weft yarn distribution on 3D woven composites under impact loading

This paper provides new insights into the impact resistance of 3D woven composites from a weft yarn distribution perspective. Two 3D through-thickness angle interlock (3D ATT) woven composites with aligned and misaligned weft yarn distributions were prepared for investigation. And a macro-meso combination model based on a bottom-up multi-scale framework was constructed to elucidate the damage evolution and dynamic response mechanisms of the composites during impact. The results show that the misaligned structure has superior impact resistance, more dispersed damage distribution, and less permanent damage at similar area density. The synergistic effect of finely dispersed resin pockets and misaligned yarns helped to retard the damage evolution, thereby improving the performance. The multi-scale simulation framework proved to be an effective tool for analyzing the mechanical properties of 3D woven composites, with misaligned weft yarns playing a critical role in stress and damage distribution. This research will aid in the design and application of 3D woven composites in impact resistant fields such as bird impact, ballistic impact, and explosions.

A data-driven ductile fracture criterion for high-speed impact

Data-driven methods based on machine learning (ML) models offer new approaches for characterizing the fracture behavior of advanced elastoplastic materials. In this paper, a ML-based data-driven ductile fracture criterion is proposed to characterize the fracture behavior of elastoplastic materials under high-speed impact loading conditions. To reduce the required training dataset and enhance the predictability capability, several assumptions are used. Firstly, utilizing the decoupled assumption, two separate artificial neural network (ANN) models are employed to establish the fundamental fracture model and characterize the strain rate effect of ductile fracture behavior, respectively. In addition, the enhanced method with a logarithmic function is introduced to improve predictability capability of the proposed data-driven criterion under unknown high strain rates. To establish a complete numerical implementation framework, an enhanced rate-dependent data-driven constitutive model and a compatible numerical implementation algorithm are additionally introduced. Eventually, to assess the applicability of the proposed data-driven fracture criterion, numerical simulations of notched specimens and ballistic impact conditions of Ti-6Al-4V material are conducted, respectively. These investigation results demonstrate the effectiveness of the proposed data-driven ductile fracture criterion.

Research on high-velocity ballistic impact of para-aramid sateen fabric with ZnO nanorods oriented to the development of soft body armor

This study introduces an innovative approach of utilizing ZnO nanorod growing technology to the sateen fabric in order to improve its ballistic performance. Through SEM, FTIR, XRD and XPS analyses, ZnO nanorods with majority length of 1000–1500 nm and fineness of 200–600 nm have been deposited on the surface of sateen fabric surface Compared the fabric with ZnO nanorods (S-11-Nrs) with its neat counterpart, the mechanical properties of S-11-Nrs are increased, especially the inter-filament friction and fabric tensile breaking strength. However, in the impact process, the number of filaments involved in the impact is reduced and the filaments are mainly failure by the shear action of the bullets. Due to these positive and negative effects, the energy absorption of S-11-Nrs displays inferior ballistic energy absorption. Nevertheless, at lower areal density, in the non-perforation test, S-11-Nrs presents less BFS and shows better resistance to the consecutive shotting process compared with the neat fabric. The reason is that the increase of inter-filament friction limits the movement of filaments and thus results in less BFS. In addition, the flexibility, air permeability and moisture permeability are still kept. This research offers valuable insights for the design and development of comfortable soft body armor.

Experimental and numerical study on ballistic impact behavior of explosively-welded double-layered Weldox700E targets against ogival-nosed projectiles

In this work, explosive welding technique was used to fabricate 2 mm + 2 mm thick double layered Weldox700E steel targets. The bonding interface exhibited wave-shaped patterns without obvious micro-defects, grain refinement and grain elongation were observed. With specially designed shear specimen and tensile specimen, Ultimate stresses of the bonding interface under shear and tensile loadings were measured to be 526 MPa and 683 MPa, respectively. Ballistic impact tests against ogival-nosed projectiles were conducted on both explosively welded double-layered targets and double-layered contact targets. Ballistic limit velocities of the two target configurations were respectively 225.32 m/s and 203.98 m/s , with the former being 10.5 % higher than the latter. For both target configurations, localized bulging and petal-shaped cracking were observed; specially, welded bonding interface remains well bonded even after perforation of the projectile. Combining experimental results and numerical simulations, it was found that the explosively welded double-layered targets exhibited better ballistic performance than double-layered contact ones. The good welded bonding interface provides a better overall deformation capability for the explosively welded double-layered target, which is an important reason for the improved ballistic performance of the target. Although hardness tests show that there is a significant hardened layer in the explosively welded double-layered target, and the hardness value can reach up to 409.4 HV. However, the thin hardened layer cannot significantly improve the ballistic performance of the explosively welded double-layered target in the high-speed impact process of the projectile.

Hypervelocity impact against aluminium Whipple shields in the shatter regime with systematic parameter variation: An experimental and numerical study

Aluminium Whipple shields are commonly used to protect spacecraft against hypervelocity impacts (HVIs) from orbital debris and micrometeoroids. Since numerical models nowadays are vital in the design process of protective shields, experimental studies of HVI are important to ensure that the numerical methods are robust and capable of accurately describing a range of impact conditions and material responses. The shatter regime is the transition velocity range between ballistic impact and hypervelocity impact, typically defined from 3 to 7 km/s. In this region, the debris cloud generated by the impact transitions from a few large, solid fragments at the lower end of the velocity range, to a high number of smaller fragments and partial melting of the projectile at the higher velocities. In this study, an experimental campaign of 22 normal impacts of spherical AA1100 projectiles on AA6061-T6 Whipple shields is performed, where the impact velocity and bumper thickness are systematically varied to study the change in debris cloud characteristics and shield damage. Impact velocities from 2.6 to 5.0 km/s are investigated, combined with bumper thicknesses of 1.0, 1.5 and 2.0 mm. Analysis of the experimental results is conducted using high-speed camera footage of the debris clouds and post-impact analysis of bumpers and rear walls. A numerical model is then established using the Smoothed Particle Hydrodynamics (SPH) method in the IMPETUS Solver, and the numerical results are compared to the experimental data. The simulations are able to capture the main trends found in the experimental study, and show a similar level of damage as the experiments when varying the impact velocity and bumper thickness. The simulations have somewhat smaller fragments generated in the debris cloud than in the experiments, leading to slightly less damage inflicted on the rear wall.

Manipulation of mechanical properties and ballistic performance by armor-grade composite processing

For the armor-grade composite, the resin bonding force cannot be too high or too low in order to achieve maximum utilization of high-performance fibers to ballistic impact. This study aims to identify the influence of the resin bonding of armor-grade composite on mechanical properties and ballistic performance. The varied resin bonding force of the panel was manipulated by the composite processing. After resin coating and curing, yarn mobility in fabric was almost fully constrained with 90% reduction, which was benefit for minimizing Backface Signature (BFS) of armor-grade composite. Tensile strength was improved 12.45% for the prepreg (FP/R 15) and 52.87% for the laminate (FL/R 15) due to better synchronous failure of filaments. However, specific energy absorption was degraded during composite processing, such as 10.74 ∼ 27.84% reduction in comparison with the neat fabric. This was because the dominant failure mode was gradually varied from tensile failure of fabric to shear failure of composite.

BPNN-based prediction for the shapes of a petal hole induced by hydrodynamic ram

The attitude angles of a projectile moving through a liquid are important factors that influence the dynamic failure of liquid-filled structures induced by hydrodynamic ram (HRAM). In this study, the effect of the attitude angles of a cylindrical projectile on the shapes of the petal hole in the rear plate of a kerosene-filled tank was investigated through ballistic impact experiments using three-dimensional digital image correlation, finite element simulations, and a back propagation neural network (BPNN). The inclination angle λ characterizing the shapes of the petal hole was related to the projection shapes of the projectile when impacting on the rear plate. The formation of petal-hole shapes was also accompanied by the formation of plastic hinge lines in the rear plate. Additionally, a method combining a BPNN and physical equations that accurately predict the drag coefficient and motion of a projectile moving through a liquid was proposed. A function describing the shapes of the petal hole was provided in the 2D space of the two initial attitude angles. The results provide offer insights into trajectory stability during liquid entry and aid in predicting the dynamic failure mode of a liquid-filled tank induced by HRAM.

Experimental and Numerical Modelling of Ballistic Impact on Fiber Metal Laminates Based on Aramid Fiber Reinforced Epoxy

This paper investigates the ballistic impact behavior of fiber metal laminates (FML) composed of aramid fiber-reinforced epoxy with a central layer of aluminum alloy Al5083. The research examines the ballistic performance influenced by factors such as hole shape and depth in the laminate and integrates both macro and microstructural analyses of FMLs. The FML variations studied included a perforated first layer with hole diameters of 3 mm and 5 mm, through which bullets penetrated. Ballistic tests were conducted from a firing distance of 5 meters using 9-mm cartridges loaded with full metal jacket bullets approximately 25 mm wide, fired at an angle perpendicular to the target surface. The experimental and simulation ballistic impact tests closely matched, with a 95.63% agreement and an error margin of about 4.37%. The FML resisted bullet impact by allowing perforation through three layers (the aluminum plate and the first and second aramid/epoxy plies) while forming a bulge due to longitudinal deformation in the final layer (the back plate). The experimental and simulation results showed similar trends, with a 5 mm diameter hole leading to a deeper bulge on the backside. Bullet penetration at the center, following a square pattern, resulted in the smallest bulge formation and a reduction in both initial and final bullet velocities. The fracture morphology indicates a ductile fracture, characterized by dominant dimple formations across the surface. The dimples in the FMLs are coarser than those in monolithic aluminum plates due to the reduced bullet velocity as it penetrates each layer of the target FMLs, significantly decreasing the remaining bullet velocity. In contrast, monolithic aluminum plates exhibit a minimal velocity decrease, resulting in smoother dimple fractures.

Micromechanics-based multi-scale framework with strain-rate effects for the simulation of ballistic impact on composite laminates

The performance of composite materials and structures at high-velocity impacts reaching or exceeding their ballistic limit is crucial for assessing their strength and safety in aerospace applications. In this highly transient impact regime, composite materials are subject to multiple complex failure modes and their properties are susceptible to strain rate effects, making very challenging the simulation and understanding of their ballistic impact performance. This study presents: (1) a multi-scale computational framework for predicting the ballistic limit of composite plates, and (2) experimental results of ballistic impacts on carbon/epoxy plates. The multi-scale model uses a micromechanical approach to account for strain-rate dependency, to calculate micro-stress effects on the matrix and fiber properties, and to predict their coupled effect on effective composite properties. Intralaminar damage initiation and evolution are identified using the maximum stress criterion, but the degradation of properties in the matrix and fibers is predicted with the micromechanics model. Mixed-mode damage laws are implemented to simulate delamination, which guarantees accurate and reliable results. The proposed multi-scale model has been implemented and integrated into ABAQUS/Explicit (VUMAT). Experimental results from high-velocity steel ball impacts on woven IM-65 Carbon/RTM6 epoxy composite plates conducted on a high-speed impact test bench are also presented including non-destructive evaluation of the types of damage and failure. The experimental results are finally used to validate the model predictions for the ballistic limit and the predicted types of damage and failure.

Bio-inspired helicoidal hemp/basalt/polyurethane rubber bio-composites: Experimental, numerical and analytical ballistic impact study with residual velocity prediction using artificial neural network

Recent body armour trends emphasize mobility, flexibility, and cost reduction while maintaining ballistic effectiveness through the use of natural fiber composite. This study evaluates the ballistic impact performance of soft and hard armor using experimental, analytical, numerical, and machine learning methods. We developed a soft armor bio-composite using monolithic, hybrid, and helicoidal structured Hemp (H)/Basalt (B)/Polyurethane (PU) rubber and tested its V50 ballistic limit according to Millitary-Standred-662 F. For hard armour, a multi-layer armor system (MAS) consisting of Al2O3/SiC ceramic, intermediate soft armour bio-composites, and an Aluminum (Al)-5052 plate backing was tested with armour-piercing bullets as per National Institute of Justice (NIJ)-0101.06 standards (Level IV). Soft armor performance was evaluated using macro-homogeneous finite element (FE), the Ipson-Retch analytical, and an Artificial Neural Network (ANN) regression model. Results showed minimal discrepancies from experimental data, with differences of 13.33 %, 12.08 %, and 8.08 % in V50 ballistic limit. The mechanical and thermal behaviors of bio-composites were assessed using un-notched Charpy, FTIR, and TGA methods. Helicoidal laminates improved Charpy toughness by 9.44 %, 19.30 %, and 40.28 % compared to hybrid and monolithic ([H]15 and [H]10) laminates, and exhibited lower weight reduction at high degradation temperature of 395.76 ℃. Helicoidal laminates increased V50 ballistic performance by 155.80 %, 76.22 %, and 16.61 % compared to [H]10, [H]15, and hybrid laminates, respectively. Due to spiral load distribution reduces stress concentration and enhanced the damage resistance of the laminate. Stand-alone soft armor demonstrates crater formation and radial cracks (petaling) due to fiber wedging and the shearing effect of a bullet. In conclusion, MAS revels a maximum back face deformation (BFD) of 18.06 mm. Al2O3/Helicoidal/Al-plate MAS reduced weight and cost by 69.21 %, and 233.72 % compared to Kevlar™-based MAS, promoting sustainable, lightweight, economical designs. Due to its higher fracture toughness and lower density, SiC ceramic in MAS provides lower trauma and further reduced weight compared to Al2O3 ceramic.

Experimental and numerical study on CuO/ZnO-modified aramid fabric for ballistic and UV radiation protection

Aramid fabrics are widely used in bulletproof armor because of their excellent mechanical properties. Previous studies have shown that ultraviolet radiation has a negative effect on the mechanical properties of aramid yarn, so improving the mechanical properties and impact resistance of aramid fabrics under ultraviolet radiation has become a research focus. In this work, aramid fabric was modified with CuO and ZnO particles to improve its ballistic performance under ultraviolet radiation. The ballistic impact resistance response and microscopic failure mechanisms of aramid fabrics under ultraviolet radiation were analyzed in detail. Under ultraviolet radiation, the ballistic limit velocity (vbl) of the CuO/ZnO-modified aramid fabric was 185.1 % greater than that of a neat fabric with a similar areal density. The vbl of the single-layer modified fabric was 45.6 % greater than that of the two-layer neat fabrics. The decrease in the ballistic performance of the aramid fabric under ultraviolet radiation was attributed to surface damage caused by the fracture of the chemical structure of the fibers, which weakened the mechanical properties of the fabric. The numerical simulation results were highly consistent with the ballistic impact test results, and the error between the numerical simulation and experimental results was within 10 %. The effects of changes in the mechanical parameters of the fabrics on the protection mechanism and energy absorption structure during ballistic impact were investigated. The energy dissipation of the modified fabric was at least 147.7 % greater than that of the neat fabric, further explaining the significant improvement in the ballistic performance of CuO/ZnO-modified fabrics under ultraviolet radiation.

Facile armour production from cocoon waste by a cold-pressing process

Utilising cocoon waste as reinforcement in composites offers a cost-effective alternative for soft body armour production. Cocoon waste, including damaged or uncoiled cocoons and those with pupae, is recognised as an eco-friendly choice. This study aims to develop and assess the incorporation of varying amounts of cocoon waste as reinforcement in epoxy resin matrix composites through the cold-pressing process. The cocoon waste content in the composite specimens ranged from 0 to 40 wt%. Tensile testing and ballistic impact testing were conducted to evaluate specimen performance. The cocoon waste composite plate exhibited a maximum tensile strength of 62.21 MPa at 30 wt%, slightly surpassing that of woven hemp. These findings indicate the advantageous reinforcement attributes of cocoon waste. However, a limitation was identified: bullets fully penetrated the composite plate. To address this, ultra-high-molecular-weight polyethylene was incorporated into cocoon waste composites, resulting in enhanced tensile strength (107.36 MPa) and complete bullet penetration prevention. These outcomes position the study as a promising avenue for developing body armour plates meeting the stringent level II certification standards set by the National Institute of Justice.

Analysis of the ballistic impact on sandwich panel: influence of attack angle and target location in structure–bullet interaction

Analysis of the ballistic impact on sandwich panel: influence of attack angle and target location in structure–bullet interaction

Experimental and numerical analysis of ballistic impat and material characterization of GFRP and Kevlar 29/epoxy composite laminate

Through experimental testing and numerical simulations, this study examines the effects of ballistic events on thin FRP composite laminated plates fabricated using a hand lay-up method. Experimental ballistic impact tests using a pneumatic gun are conducted on composite plates reinforced with woven glass and woven Kevlar 29 fibers. An advanced three-dimensional finite element model programed in Ansys/Autodyn v19.1 is employed to verify the experimental findings and analyze the ballistic perforation characteristics of the target. The crucial material constants needed for the constitutive material model used in the simulation are acquired through precise experimentation on samples prepared from the fabricated laminates. Significant agreement is observed between the FE simulations and experimental findings, particularly concerning the assessment of residual velocities of the projectile and damage pattern in the laminates. The results of this study show that when subjected to ballistic impact by a flat-ended cylindrical projectile, the thin woven FRP composite primarily experiences damage characterized by delamination, fiber breakage and matrix cracking. Additionally, based on current simulations, it is observed that the ballistic limit velocity of the Kevlar 29/epoxy laminate exceeds that of GFRP by 25.64% when both materials have an equal thickness of 2.8 mm.

Ballistic resistance of ceramic and metal target plates impacted against different projectile’s nose shape: A numerical investigation

Layered ceramic/metal plates are investigated for ballistic impact against projectiles with different nose shapes. Explicit finite element method is used to model the target and projectile. This study examines the effect of nose shapes on the ballistic performance of target. This includes replacing the metallic layer with a ceramic plate of the same thickness to identify the best ceramic-to-target plate ratio for maximum BLV. Ballistic performance is compared between two different configurations having equal total thickness of ceramic and metallic layer. Increased ceramic layer thickness upto certain thickness-ratio may significantly improve the target plate’s ballistic resistance for all bullet types.

Ballistic performance of aluminum alloy plates with polyurea coatings for high-speed train structures

Polyurea coatings have been widely promoted in explosion and ballistic impact protection applications due to their excellent hyper-elasticity performance. In rail transportation, high-speed trains face potential impact threats from track ballast, which can affect the strength performance of the base material. To address these challenges, we examined the ballistic performances of aluminum alloy plates with polyurea coatings under large-scale impact (>30 mm). Four different configurations of target plates were investigated: A, P-A, A-P, and P-A-P. We fabricated samples and performed dynamic impact tests using an air cannon system to demonstrate the feasibility. Results show that ballistic performance is significantly improved by applying polyurea coatings on aluminum alloy plates. In particular, the growth rate of limit velocity of configuration A-P, P-A, and P-A-P to that of configuration A are 5.5 %, 19.4 %, and 22.8 %, respectively. The enhancement mechanism was further uncovered through stress wave propagation analysis and lateral energy diffusion effect. Explicit formulas for predicting the limit velocity and residual velocity were derived and demonstrated with reasonable accuracy over a wide range of parameter spaces. The observed enhancement in ballistic performance through polyurea coatings on aluminum alloy plates offers promising ways to design and implement more resilient and impact-resistant high-speed train structures.

Biomimetic 3D-printed Composites: Ballistic Impact Resistance with Nacre-Inspired and Tubulane Structures

This research delves into nature-inspired designs for creating materials with exceptional impact resistance, leveraging cutting-edge 3D printing techniques. Our composite design features a nacre-like outer layer combined with a tubulane-resembling core, aiming to enhance energy dissipation significantly. By emulating the dense aragonite structure found in natural nacre and the unique porosity of tubulane, to enhance ballistic impact resistance. To validate its effectiveness, we conducted ballistics tests using a 40-grain lead-tipped .22 LR bullet at an initial velocity of 330.7 m/s, with a specialized chronograph setup to measure both initial and post-penetration bullet velocities, quantifying energy absorption precisely. This study opens new frontiers in aviation safety, structural engineering, and personal protective equipment, showcasing the transformative potential of biomimicry and additive manufacturing in advancing public safety and material science.

Ballistic impact behavior of shear thickening fluid impregnated sisal fabrics

The study explores the ballistic impact performance of shear thickening fluid (STF) impregnated sisal fabric panels with varying nano silica loadings (10 wt%, 20 wt%, and 30 wt%). Rheological analysis indicated improved shear thickening behavior with increased nano-silica. FESEM, XRD, and FTIR analyses were conducted to assess changes in morphology, phase structure, and functional groups. The yarn pull-out test showed a higher pull-out force for STF-impregnated fabrics, with 30 wt% STF demonstrating the highest pull-out speed. Ballistic impact tests revealed significant improvements in energy absorption for STF-impregnated fabrics compared to neat fabrics, with energy absorption enhancements of 4.40% for 10 wt%, 45.09% for 20 wt%, and 50.17% for 30 wt%. The increased nano-silica loading resulted in greater energy absorption, attributed to enhanced inter-yarn friction and improved fabric integrity.

An experimental and numerical investigation of ballistic penetration behaviors of deployable composite shells

Bistable composite shells are suitable candidates for deployable space structures due to high stiffness to weight ratio as well as large volume reduction. Nevertheless, impact performance of bistable composite shells conflicting with space debris have been rarely studied. In this paper deployable hybrid composites constructed with combinations of carbon–carbon, carbon–kevlar, kevlar–kevlar, high-energy-absorption graphene-reinforced polyurethane elastomers are developed, and their ballistic penetration behaviors are experimentally and computationally studied. The influences of ballistic velocity on the absorbed energy, the residual velocity and damage morphology of the targets are investigated in both deployed and coiled stable states. The results show that severe local damages were observed for the carbon–carbon and carbon–kevlar samples after penetration with various velocities even first cosmic velocity, and the sample of deployable hybrid composite shell yielded the best ballistic impact resistance. The total energy absorption performance of the hybrid composite structure was greatly improved by introducing graphene-reinforced polyurethane elastomers without losing the deployability. Additionally, investigation on the energy absorption capability of deployed laminated shells with various curvature radii indicated that the curvature radius had a significant effect on the anti-penetration performance.