Simulation Of Ballistic Impact Research Articles

Simulation of Multi-Layered Ballistic-Resistant Armour with Enhanced Energy Absorption Properties

This research focuses on the simulation of ballistic impact on multi-layered ballistic resistant armour. The efficiency of spring-loaded backing plate armour was compared with armour that has solid end plate with a view to introducing a more elastic surface that enhances energy absorption properties. The design consists of three major layers of different materials: fibre cement as the first layer; Kevlar as the second; and a spring-loaded backing plate made of steel as the third layer. SolidWorks was used to model the multi-layered armour and ANSYS Workbench Explicit Dynamics and AUTODYN 3D solver were used to simulate the ballistic impact. The simulation involved testing different configurations of the multi-layered structure. Analysis of the effect of the spring wire diameter on the armour's energy-absorbing characteristics was carried out while keeping the overall weight within the acceptable range. The simulation results for the different configurations were compared and the ballistic-resistant armour designed with a spring-loaded backing plate of 0.40 mm spring wire diameter gave the least deformation. The research suggested an enhanced armour performance using embedded elastic material.

A progressive damage model associated with dynamic fracture toughness and IFF criterion with a fast search algorithm of fracture angle

This paper presents a quick search algorithm of the fracture angle of inter-fiber fracture (IFF) criterion and a progressive damage model considering the dynamic fracture toughness effect. The fracture angle determination of the IFF criterion is necessary and time-consuming, which has limited its practicality. Therefore, to accurately calculate stress exposure factors under various combinations of stress states, a highly efficient algorithm is needed. In this paper, a novel algorithm using stress tractions on the fracture plane and the golden section search (GSS) is promoted. Through a series of simulation tests, this novel algorithm has been proven to be exact and efficient compared with other two common algorithms, which saves an average of 63.2 % and 28.1 % of the time in 1 million calculations and 2 h 2 min 4 sec and 39 min 2 sec in simulations. Additionally, fracture toughness, which controls material damage evolution process, also has strain-rate effect like elastic modulus and strength. Hence, a new progressive damage model considering the dynamic fracture toughness effect is proposed. The results of dynamic compression and ballistic impact tests and simulations demonstrate the fidelity of the novel damage model.

A data-driven approach for predicting the ballistic resistance of elastoplastic materials

Data-driven methods and machine learning methods provide efficient and accurate approaches for solving impact problems. In this paper, a data-driven approach is proposed for numerical simulations of ballistic impact behavior for elastoplastic materials. An enhanced rate-dependent scheme is employed for improving the predictability of the data-driven constitutive model. A new method that introduces a stress triaxiality indicator to three separate constitutive models is proposed to consider the discrepancy between the mechanical responses of materials under tension, compression, and shear. Additionally, a modified Bai-Wierzbicki fracture criterion considering the strain rate effect and the stress-state effect is used to evaluate the fracture behavior of the materials during impact simulations. Subsequently, a compatible numerical implementation algorithm that considers loading, unloading, and reverse loading is established to enable the application of the data-driven approach in finite element simulations. Numerical validation of the proposed data-driven approach is conducted through several simple loading examples, such as cyclic loading, torsional loading, and tension–torsion combined loading. The data-driven approach is then employed to simulate the ballistic impact behavior of Ti-6Al-4V targets of different thicknesses that are struck by blunt projectiles. Impact properties—including the relationship between residual velocity and impact velocity, ballistic limit velocities, and fracture paths—are comprehensively studied. The results demonstrate the reasonable predictability and accuracy of the data-driven approach when applied to ballistic impact simulations.

A numerical ballistic performance investigation of Armox 500T steel through ductile damage models

In this work, the ballistic response of an armor steel, Armox 500T, is numerically investigated through finite element (FE) analysis by utilizing the Johnson–Cook (JC) and modified Mohr–Coulomb (MMC) damage models, with a focus on emphasizing the consequences of different modeling approaches. Although Lode-dependent failure models are considered to increase the accuracy of numerical predictions for ductile failure, there remains a complete lack of clarity as to whether all conditions and materials necessitate the adoption of such models for ballistic impact simulations. In this context, MMC and JC model parameters are calibrated through tensile test data available in the literature enabling direct comparison between them. Damage models are then validated using ballistic impact tests of Armox 500T performed with 7.62 API projectiles. The results indicate that the MMC model outperforms the JC model at predicting the failure modes while both models demonstrate strong performance in anticipating the residual velocity. The influence of projectile nose shape, target plate thickness, and impact angle are further investigated, and the effect of incorporating the Lode parameter is discussed in detail. Impact simulations with the blunt projectile nose shape is found to be highly sensitive to the effect of Lode angle on failure, with differences of up to 20% between models, while 7.62 API shows the lowest sensitivity. The difference between the models’ predictions is observed to increase at lower impact velocities and higher impact angles demonstrating the necessity of a Lode-dependent failure model for such cases. The JC model consistently yields smaller residual velocities compared to the MMC model in all cases indicating that the MMC is more conservative in terms of predicting protective performance of Armox 500T.

Advancements in numerical modelling of synthetic gel for ballistic impact assessment

A synthetic gel based on SEBS (styrene-ethylene-butylene-styrene), commonly used as a human soft tissue simulant, was characterised over a wide range of strain rates. Material parameters were derived from quasi-static and dynamic tests using DMA. These parameters were then integrated into a visco-hyperelastic material law based on an Ogden model. Ballistic impact simulations showed good agreement with experimental analysis.

Numerical Analysis of the Impact Resistance of Composite A-Shaped Sandwich Structures.

This paper focuses on the finite element analysis simulation of the impact properties of composite sandwich structures made of carbon fiber-reinforced polymer lamina. In the existing studies, the composite sandwich structures with A-shaped cores have superior mechanical properties under quasi-static plane compression loads compared to W-shaped, Y-shaped, and X-shaped cores. However, there is limited research on the impact resistance of this structure. This paper studied the resistance of a composite A-shaped core structure to ballistic impact. Using ABAQUS/explicit finite element analysis software, ballistic impact tests for the composite A-shaped core structure were simulated based on the Hashin and Yeh failure criteria with a progressive damage model introduced in the user-defined subroutine VUMAT. First, the composite Y-shaped core sandwich structure was verified via experiments and simulations to determine the accuracy of the method, and then the composite A-shaped sandwich structure was subjected to a series of ballistic impact simulations. With varied impact velocity, the damage to the front and rear face sheet and cores via ballistic loads was simulated to illustrate the overall dynamic response process of the sandwich structure. Subsequently, a curve was fitted using a ballistic limit velocity equation, which was used as the criterion to evaluate the impact resistance of the composite A-shaped core structure. The results showed that, under the same relative density and the same number of component layers, the ballistic limit velocity of the composite A-shaped core sandwich structure was bigger than the composite Y-shaped core sandwich structure. The composite A-shaped core structure had 12.23% higher ballistic limit velocity than the composite Y-shaped core, indicating the impact resistance capabilities of the A-shaped core structure. In addition, the impact location's effect on the impact response was investigated.

Modeling of hyperelastic polymer gels under blunt ballistic impact with three-dimensional flexibilities

Polymer gels are promising surrogates for human tissues, whereas simulating the behavior of these materials in 3D scenarios, particularly when they are subjected to dynamic loads, can be a complex and computationally demanding task. This work presents a solution to this challenge through developing a three-dimensional meshfree framework based on bond-based peridynamics. The novelties of this method are threefold: (1) The peridynamic bond force–stretch​ relationship of the Mooney–Rivlin hyperelastic model is original formulated and implemented based on thermomechanical theories and energy equivalence principles; (2) A novel contact algorithm is proposed to reduce the complexity of realistic loading and boundary conditions in blunt ballistic impact simulations; (3) This computational framework enables 3D dynamic simulations of hyperelastic polymer gels with complex geometric configurations. Tensile and compressive tests with varying loading rates are studied to validate the capability and accuracy of the proposed method. The proposed computational framework outperforms its finite element counterparts in modeling blunt impacts on polymer gels. It can be readily extended to penetration impact problems since accounting for failures is straightforward in this peridynamics framework.

Combining protective clothes with human body models for finite element ballistic impact simulations

The ballistic deformation of an ultra-high-molecular-weight (UHMW) polyethylene (PE) composite has been subjected numerically to a multi-layered soft ballistic fabric package modelled upon the body contours of the Global Human Body Models Consortium (GHBMC) human body models M50-P and F05-P. The results of the clothing-body-interaction have been investigated and compared to the behavior of anthropomorphic surrogate models made from ballistic clay. For building the fabric model in donned shape, a single ply of woven fabric material has been converted upon the anthropomorphic body contour by subjecting it to a quasi-deep drawing process. After the fabric deformation, the shaped layer was duplicated 20 times and shifted outwards to build the fabric model, representing a multi-layered soft ballistic fabric package. The results of the ballistic impact simulation show that the response of the human body models (HBMs) is much more compliant than the behavior of the surrogate models. The deformation of the female HBM in terms of penetration depth and diameter of the affected impact region is slightly more severe than the deformation of the male counterpart with respect to identical impact conditions.

Evaluation of automatic versus material test-based calibrations of concrete models for ballistic impact simulations

Concrete is used for protective structures all over the world. Accurate response estimates to a given threat is vital for designing such structures. Concrete models often require numerous input parameters for which sufficient experimental data can be challenging to obtain. Some models are accompanied by parameter generators which use the unconfined compression strength to extrapolate the remainder of the parameters based on experimental databases. This study investigates simulation of ballistic impact on high-strength concrete with 75 MPa nominal unconfined cylindrical compressive strength. The first objective is to investigate the accuracy parameter generators to produce input data for commonly used concrete material models. The second objective is to establish and evaluate a simplified parameter calibration procedure based on standard material experiments and data from the literature. The results employing parameter generators varied notably between the models while still giving decent ballpark estimates. The parameters obtained from inverse modelling of standardized material tests improved the results significantly. The findings of this study recommend caution when using automatic parameter generators. Although a detailed calibration of these concrete models is complicated, a simplified calibration gives reasonable predictions, making this the advisable approach for designing concrete protective structures.

Experimental and numerical study on failure mechanisms of bone simulants subjected to projectile impact.

Analyses of the human bones failure mechanisms under projectile impact conditions can be made through performing of a large number of ballistic trials. But the amount of data that can be collected during ballistic experiments is limited due to the high dynamics of the process and its destructive character. Numerical analyses may support experimental methodologies allowing to better understand the principles of the phenomenon. Therefore, the main aim of the study was to create and to verify a numerical model of commercially available synthetic bone material-Synbone®. The model could be used in the future as a supporting tool facilitating forensic studies or designing processes of personal protection systems (helmets, bulletproof vests, etc.). Although Synbone® is commonly used in the ballistic experiments, the literature lacks reliable numerical models of this material. In order to define a numerical model of Synbone®, mechanical experiments characterizing the response of the material to the applied loads in a wide range of strains and strain rates were carried out. Based on the mechanical tests results, an appropriate material model was selected for the Synbone® composite and the values of constants in its equations were determined. Material characterization experiments were subsequently reproduced with numerical simulations and a high correlation of the results was obtained. The final validation of the material model was based on the comparison of the ballistic impact experiments and simulation results. High similarity obtained (relative error lower than 10%) demonstrates that the numerical model of Synbone® material was properly defined.

Fluid-structure interaction simulation and evaluation of ballistic impact of STF impregnated UHMWPE fiber composites

This study reveals the fluid-structure interaction simulation of the ballistic impact of shear thickening fluid (STF) impregnated with ultra-high molecular weight polyethylene (UHMWPE) fiber composites. The STF/UHMWPE composites pull-out test results are fitted to obtain a similar STF rheological curve. The STF/UHMWPE composites fluid-structure interaction (FSI) model was established to reproduce the local failure and stress distribution at each stage of the ballistic impact process. The comparison of the finite element analysis (FEA) and the experimental results showed that the fitting degree of the STF/UHMWPE composites to the impact energy absorption was 94.74%. STF treatment has dual effects on the impact resistance of fabrics, increasing the friction and enhancing the thickening effect.

Study on physical behaviors according to element formulations of ballistic impact simulation models

During modeling ballistic impact, physical behaviors were investigated according to element formulations. In order to conduct the investigation, a simple ballistic impact simulation model was used. Several case studies consisting of FEM (Finite Element Method) and SPH (Smoothed Particle Hydrodynamics) models were conducted using the LS-DYNA research/commercial code. As a result, these case studies suggest that the SPH formulation is effective to simulate interactions among particles after failures so that the penetration phenomenon of the projectile were well described. In addition, some parameters relating to the SPH formulation such as particle spacing and smoothing length constant were investigated. Finally, for the verification, 20 mm fragment simulating projectile tests to verify the protection performance of K9 Thunder grill louver were compared with the simulations applying the FEM and SPH formulations.

Experimental and numerical evaluation of the perforation resistance of multi-layered alumina/aramid fiber ballistic shield impacted by an armor piercing projectile

Multilayered Armor System is an efficient protection which combines a ceramic front layer and ductile backing usually made by a metal or a composite material. Numerical models are an effective tool to design ballistic protections. Such models may be used as virtual tests, strongly reducing the efforts for experimental testing. Moreover, numerical models can be used for optimization of protections. However, the correct definition of such models is not straightforward and requires strong expertise both in material and numerical modelling. Fragmentation of ceramic cannot be correctly simulated by the Finite Element method, which is commonly used in the literature. Indeed, the Finite Element method requires the implementation of element erosion which is introduced errors due to mass and energy loss. To solve this issue, the aim of this work is to develop and validate a Finite Element coupled to Smoothed Particle Hydrodynamics model for the simulation of ballistic impact against a Multilayered Armor System. Experimental tests were performed to obtain the ballistic curve for the 7.62 × 51 P80 bullet on a full Multilayered Armor System (Kevlar®29/epoxy cover, alumina tiles and Kevlar®29/epoxy backing), obtained using a one-stage vacuum infusion. Consequently, the numerical model was validated showing good agreement with the experimental results.

Numerical simulation of ballistic impact on multilayer ceramic backed fibre reinforced composite target plate

Fibre reinforced polymer composites have been established as potential materials for making body armours. The present work depicts estimation of ballistic resistance of multilayer ceramic backed fibre reinforced composite target through 3D numerical simulation using Ansys/Autodyn software. The present numerical and material models have been validated against the results available in the literature. After that, the velocity–time history of the projectile is examined for impact velocities ranging between 330 to 1200 m/s. Here, the study has been focused on predicting the progressive damage and failure modes of the ceramic-composites target plate under impact. Also, the variation in residual velocities, time of penetration/perforation with different incident velocities, damage pattern in the deformable projectile and the kinetic energy of the impactor is studied. Finally, the trend of variation of ballistic limit velocity with different masses and diameter of the impactor has also been investigated.

Effect of sphere radius and bullet hitting location on the ballistic performance of alumina ceramic tile

Designers in the defense industry aim to increase the protectiveness of armors while decreasing their weight. On-body armors, composites, and ceramics are widely used due to their lightweight, high hardness, and reduction in blunt trauma. Ceramic armor materials are usually used as the front face for their capability to erode or break up the projectile. There exist various parameters affecting the performance of ceramic armors, and one of these parameters is surface profile. It is a compelling parameter due to its ability to yaw the projectile, causing a reduction of projectile penetration capacity. This study aims to compare alumina ceramic tiles with different surface profiles in terms of their specific kinetic energy absorption (SKEA). Although experimental results are necessary due to an armor system’s acceptance, numerical results lead to a better understanding of surface profiling. In this study, LS-DYNA software is used for ballistic impact simulations to explore the effect of surface profiling. In the simulations, a steel projectile with varying velocities penetrates a ceramic tile. Johnson-Cook material model is used for the projectile, whereas Johnson- Holmquist material model is used for ceramic tiles. For the modeling of ceramic tile, smoothed particle hydrodynamics (SPH) is used to capture fractures and debris. In this study, the finite element (FE) model that simulates a projectile impacting a flat ceramic tile is generated and validated with the experimental results available in the literature. Then, surface profiled ceramic tiles having spherical surface profile with different radius values are analyzed, and their SKEA values are compared. It is found that surface profiling can increase the SKEA value up to 56% when the bullet hits the gap between four spheres. The worst ballistic performance of surface profiled tiles occurs when the bullet hits the top of the sphere; however, even the worst performance increases the SKEA value by 21%.

Dynamic mechanical behaviors of nacre-inspired graphene-polymer nanocomposites depending on internal nanostructures

Nacre, a natural nanocomposite with a brick-and-mortar structure existing in the inner layer of mollusk shells, has been shown to optimize strength and toughness along the laminae (in-plane) direction. However, such natural materials more often experience impact load in the direction perpendicular to the layers (i.e., out-of-plane direction) from predators. The dynamic responses and deformation mechanisms of layered structures under impact load in the out-of-plane direction have been much less analyzed. This study investigates the dynamic mechanical behaviors of nacre-inspired layered nanocomposite films using a model system that comprises alternating multi-layer graphene (MLG) and polymethyl methacrylate (PMMA) phases. With a validated coarse-grained molecular dynamics simulation approach, we systematically study the mechanical properties and impact resistance of the MLG-PMMA nanocomposite films with different internal nanostructures, which are characterized by the layer thickness and number of repetitions while keeping the total volume constant. We find that as the layer thickness decreases, the effective modulus of the polymer phase confined by the adjacent MLG phases increases. Using ballistic impact simulations to explore the dynamic responses of nanocomposite films in the out-of-plane direction, we find that the impact resistance and dynamic failure mechanisms of the films depend on the internal nanostructures. Specifically, when each layer is relatively thick, the nanocomposite is more prone to spalling-like failure induced by compressive stress waves from the projectile impact. Whereas, when there are more repetitions, and each layer becomes relatively thin, a high-velocity projectile sequentially penetrates the nanocomposite film. In the low projectile velocity regime, the film develops crazing-like deformation zones in PMMA phases. We also show that the position of the soft PMMA phase relative to the stiff graphene sheets plays an important role in the ballistic impact performance of the investigated films. Our study provides insights into the effect of nanostructures on the dynamic mechanical behaviors of layered nanocomposites, which can lead to effective design strategies for impact-resistant films.

A computational framework for energy absorption and damage assessment of laminated composites under ballistic impact and new insights into target parameters

In this research, by means of advanced methods within the framework of the FE method, an effective modeling approach is proposed to simulate the ballistic perforation behaviors of multi-directional woven composite panels. Within that scope, constitutive models for intraply and interfacial or interply damage mechanisms are formulated and implemented into ABAQUS/Explicit FE code. The constitutive law of ply-level damage model incorporates the nonlinear material response, degradation of material properties, progressive failure and the element deletion scheme. The interfaces between the individual plies are modeled using a cohesive surface method, and the behaviors of interply degradation and failure are described using a traction-separation law. Besides, the material responses with large nonlinearity due to fiber rupture, matrix cracking, plasticity effects due to micro-matrix cracking under shear loading, and interface delamination are accounted for by appropriate material degradation models. The proposed developments are first validated against the available experimental and analytical results. Next, the ballistic impact simulations of woven composite targets are carried out in a two-phase research. The first phase analyzes the ballistic impact behavior and ballistic performance of the composite laminates in terms of residual velocity and energy absorbing capacity. The second phase involves the investigation of the impact characteristics and failure mechanisms of the composite materials. More specifically, the key perforation mechanisms and associated impact damage extents and patterns with respect to projectile velocity are investigated for the composite panels. We further perform parametric analysis in order to understand the influence of a certain number of parameters on the laminate ballistic impact response. These parameters are categorized based on materials such as fiber type material, interface systems, and geometry such as stacking sequences and support conditions. Numerical results reveal that the ballistic impact performance depends significantly on the cohesive material properties, the stacking sequence, and the woven fabric material, whereas less contribution of support conditions to the ballistic perforation characteristic is noticed.

A machine learning model for predicting the ballistic impact resistance of unidirectional fiber-reinforced composite plate

It has been a vital issue to ensure both the accuracy and efficiency of computational models for analyzing the ballistic impact response of fiber-reinforced composite plates (FRCP). In this paper, a machine learning (ML) model is established in an effort to bridge the ballistic impact protective performance and the characteristics of microstructure for unidirectional FRCP (UD-FRCP), where the microstructure of the UD-FRCP is characterized by the two-point correlation function. The results showed that the ML model, after trained by 175 cases, could reasonably predict the ballistic impact energy absorption of the UD-FRCP with a maximum error of 13%, indicating that the model can ensure both computational accuracy and efficiency. Besides, the model’s critical parameter sensitivities are investigated, and three typical ML algorithms are analyzed, showing that the gradient boosting regression algorithm has the highest accuracy among these algorithms for the ballistic impact problem of UD-FRCP. The study proposes an effective solution for the traditional difficulty of the ballistic impact simulation of composites with both high efficiency and accuracy.

Numerical analysis of strain rate effect on ballistic impact response of multilayer three dimensional angle-interlock woven fabric

This paper investigates the ballistic impact on Kevlar multilayer three-dimensional angle-interlock woven fabric (3DAWF) by proposing the mesoscale geometrical model for the numerical simulation. Multilayer 3DAWF is designed to yarn level configuration by utilizing the membrane elements to reduce computational time and enhance accuracy. The general-purpose finite element code LS-DYNA is employed to predict the ballistic behavior of multilayer 3DAWF under ballistic penetration. The velocity evolution of the projectile, energy absorption mechanism, and failure morphology of multilayer 3DAWF are predicted and validated by the impact test results. It is found that the mesoscale model based on strain rate material models accurately reproduces the ballistic test results. Numerical simulations with strain rate effects in the yarn material properties have a higher precise prediction in the projectile's velocity, energy absorption mechanism, and failure morphology compared with traditional FEA. This study demonstrated the importance of the strain rate effect of material properties in simulating the ballistic impact on the fabric and dramatically improves the ballistic impact simulation's accuracy on fabric.

Ballistic Penetration Analysis of Soft Laminated Composites Using Sublaminate Mesoscale Modeling

Ballistic impact mitigation requires the development of protective armor applications from composite material systems with good energy absorption and penetration resistance against threats, e.g., metallic projectiles. In this aim, high-strength and high-stiffness soft fibrous composite materials (such as ultra-high molecular weight polyethylene—UHMWPE) are often used. The high specific strength feature is one of the main reasons for using these soft composite systems in ballistic impact applications. In the present investigation, experimental and computational finite element (FE) studies were carried out to investigate the ballistic behaviors of these soft layered composite targets. To this end, a new FE multi-scale analysis framework for ballistic simulations is offered. The proposed analysis presents a new meso-scale sublaminate material model, which is applied to Dyneema® cross-ply laminate in order to predict its behavior under ballistic impact. The sublaminate model is implemented within an explicit dynamic FE code to simulate the continuum response in each element. The sublaminate model assumes a through-thickness periodic stacking of repeated cross-ply configuration. In addition, a cohesive layer is introduced in the sublaminate model in order to simulate the delamination effect leading to the subsequent degradation and deletion of the elements. This new approach eliminates the widely used costly computational approach of using explicit cohesive elements installed at pre-specified potential delamination paths between the layers. Furthermore, in-plane damage modes (such as fiber tensile, and out-of-plane shearing) are also accounted for by employing failure criteria and strain-softening. The obtained quantitative results of ballistic impact simulations show good correlation when compared to a relatively wide range of experiments. Moreover, the simulations include evidence of capturing the main energy absorption mechanisms under high-velocity impact. The proposed modeling approach can be used as a useful armor design tool.