Hemispherical-nosed Projectiles Research Articles

Constitutive and impact response of AA7475-T7351 under different projectile shapes and velocities: An experimental and numerical investigation

Through experimental and numerical investigation, this article investigates the constitutive and impact response of the 1.6 mm thick AA7474-T7351 plate under the impact of blunt and hemispherical-nosed projectiles at different velocities. The Johnson-Cook plasticity and failure model parameters were calibrated for the target material using experimental data from the tensile experiments, which took into consideration the effects of plastic strain, strain rate, temperature and stress triaxiality. Further, JC plasticity model parameters were also optimised using a parametric optimisation process. The flow stress of AA7475-T7351 shows positive and negative sensitivity toward loading rate and temperature. It is observed that the ductility of AA7475-T7351 decreases with increases in stress triaxiality, whereas the flow stress increases. Perforation experiments on 1.6 mm thick circular AA7475-T7351 plates were carried out using a single-stage gas gun along with the high-speed Digital Image Correlation (3D-DIC) technique. The blunt nose projectile causes shear failure, whereas hemispherical nose projectile causes combined tension-shear failure; a microscopic study is performed to confirm this phenomenon. Experimental results obtained from DIC were validated using the numerical analysis in the Abaqus/Explicit platform in terms of transient out-of-plane deformation of the target plate. The quantitative error between experimental and numerical analysis was evaluated using the Russell error technique. Numerical analysis revealed that constitutive relations could predict the physical fracture mechanisms during perforation qualitatively as well as quantitatively.

Ballistic impact response of reinforced concrete panels subjected to diverse multiple projectile impact scenarios: A numerical study

Concrete has wide applications in civil and military infrastructures. Thorough ballistic damage evaluation of these structures is crucial to safeguard these structures against potential threats. Past studies on reinforced concrete (RC) panels primarily focused on single-impact scenarios. However, real-world situations often involve multiple impacts that need to be examined. Hence, this paper critically examines multiple impact scenarios on RC panels to provide a realistic understanding of their ballistic resilience. A three-dimensional finite element model was developed and validated with the experimental data from the literature to simulate the impact of a 2 kg hemispherical-nosed projectile on an RC panel. Extended analyses further investigated the RC panel subjected to multiple impact scenarios. Four distinct scenarios were studied: (1) single impacts at four separate locations, (2) simultaneous impacts at these four locations, (3) sequential impacts of four projectiles, and (4) single projectile impact with energy equivalent to the combined impact of the four projectiles. The study assessed local damage failures, including penetration depth, crater formation, energy absorption, deceleration and reaction forces on projectiles. Results revealed reduced ballistic performance of RC panels under multiple impacts compared to single impacts. Specifically, simultaneous impacts (case 2) and the equivalent single impact (case 4) caused more damage in terms of spalling and scabbing than single impacts (case 1) and sequential impacts (case 3). Additionally, cases 2 and 4 exhibited similar performance in terms of projectile penetration. This study is useful in understanding RC panels’ ballistic performance under multiple impacts.

High-velocity impact performance of sandwich panels with additively manufactured hierarchical honeycomb cores: An experimental and numerical study

The honeycomb sandwich panel presents a highly promising solution for enhancing ballistic behavior owing to its excellent strength-to-weight ratio and impact resistance. This study focuses on investigating the shock mitigation properties of honeycomb sandwich panels through experimentation and numerical simulation of high-velocity impact tests. Single-scale and double-scale hierarchical honeycomb cores are manufactured using selective laser melting with AlSi10Mg powder, combined with a pair of stainless steel (SS 316) sheets. High-velocity impact experiments were conducted within a velocity ranging from 100 to 270 m/s to examine the effects of different cores and projectile nose shapes on the dynamic response of the panels. Numerical simulations using ABAQUS/Explicit software were performed and validated against the experimental results. The sandwich panel with a double-scale hierarchical honeycomb core exhibited 7.8% and 6.1% more energy absorption compared to the single-scale hierarchical honeycomb core against conical and hemispherical nose projectiles, respectively. Additionally, the ballistic limit for the hemispherical projectile was found to be 8.9% higher than the conical-nose projectile under the same impact velocity and panel thickness. Moreover, an increase in panel thickness from 12 mm to 25 mm prompted a significant improvement of approximately 39% in specific energy absorption and a 44% increase in ballistic limit velocity. These findings highlight the considerable potential of single-scale and double-scale hierarchical honeycomb sandwich panels for the development of threat-resistant structures in critical dynamic loading applications.

Numerical investigation on effect of different projectile nose shapes on ballistic impact of additively manufactured AlSi10Mg alloy

In the last few years, due to the superior mechanical qualities of Additive Manufacturing (AM) AlSi10Mg alloy to those of traditional casting process AlSi10Mg alloys, the application of AM technology has significantly increased. The ballistic impact research has a wide range of uses, notably in the mining, construction, spacecraft and defence sectors. This work focuses on analyzing the behavior of different projectile nose shapes on the AlSi10Mg alloy fabricated by AM. There are several projectile nose forms to consider, including blunt, hemispherical, conical, and ogive shapes. The impact of various projectile shapes on the ballistic limit of the additively created AlSi10Mg alloy is carefully examined in this study. All numerical simulations were carried out using LS-DYNA software, and the Johnson-Cook material and damage model were considered to assess the ballistic resistance behavior. The ballistic limit for various projectile shapes is computed using the Jonas-Lambert model, which describes the connection between residual velocity and starting projectile velocity. The results showed that, the ogive-shaped Projectile offers the highest ballistic limit, and the blunt projectile shows the lowest ballistic limit for a 5 mm thin target plate. The ballistic impact phenomenon showed plugging failure for the blunt nose projectile, the formation of plug and small fragments were observed in the case of hemispherical nose projectile, fragmenting failure is observed with radial necking in the case of conical nose projectile and petals are formed at the impacted zone in ogive nose shape projectile. Moreover, the ballistic limit of AM AlSi10Mg alloy was slightly higher compared to the ballistic limit of the die-cast AlSi10Mg alloy for the 7.62 mm AP bullet (core). Therefore, AM AlSi10Mg alloy may have equal or good ballistic properties compared to die-cast AlSi10Mg alloy.

Perforation of carbon fiber reinforced plastic laminates struck transversely by hemispherical-nosed projectiles

This study focuses on perforation of carbon fiber reinforced plastic (CFRP) laminates struck transversely by hemispherical-nosed projectiles. Global deformation with local rupture failures for thin laminates and localized response failures for thick laminates are two common categories of the ballistic perforation of CFRP laminates. An analytical model is proposed considering these two failure modes and their transition conditions. The ballistic limit predicted for laminates in global deformation with a local rupture failure mode is given based on the energy dissipation method, and an ultimate perforation failure criterion is derived based on the bottom surface tensile fracture of the laminate. A critical transition condition of the two failure modes is obtained by combing the localized response failure model and Von Karman’s critical impact velocity concept. Model predictions agree with the experimental and numerical results regarding ballistic limits in a wide ratio range of laminate thickness H and hemispherical-nosed projectile diameter d.

Effect of Lode angle and projectile diameter on the ballistic resistance of 6061-T651 aluminum alloy plates struck by hemispherical nosed projectile

Aluminum alloy has been gradually applied to the field of armor protection because of its excellent material properties. The research on its ballistic resistance has important theoretical and engineering application value. In order to study the ballistic resistance of 6061-T651 aluminum alloy plate, the impact tests of 6061-T651 aluminum alloy plate against hemispherical nosed projectile with a diameter of 12.66 mm were carried out with a light gas gun system and the ballistic limit velocity and failure mode of the target plate were obtained. Subsequently, the numerical simulations corresponding to the tests were carried out by using the Lode dependent and independent fracture criteria, and the effect mechanism of the Lode angle on the numerical simulation results were analyzed. Finally, the effect of projectile diameter on the ballistic resistance of the target plate was analyzed by the expansion of numerical simulation. The research results show that the numerical simulation will be quite different from the test results if the effect of the Lode angle on the material fracture strain is not considered. As the diameter of the projectile increases, the armor-piercing efficiency of the hemispherical nosed projectile is improved since the energy dissipation mechanism of the target plate gradually changes from ductile hole enlargement to shear plugging.

Ballistic response of sandwich shell panels: A comparative study

The present work was carried out to explore the impact response of hemispherical (HSS), cylindrical (CSS) and flat sandwich structures (FSS) subjected to high-velocity impact through experimental and numerical simulations. All three-sandwich structures comprised of Al 1100-H12 face skins and Al -3003 H12 honeycomb core. For the direct comparison, the radius and thickness of all three-sandwich structures were kept identical. The high velocity impact tests were performed by using a pneumatic air gun. The hemispherical and conical shape projectiles were impacted typically at the centre (axis) of the sandwich structures with varying impact velocity. The finite element simulations were carried out through commercially available software Abaqus/explicit. The numerically obtained test results were validated through the experimental results to check the accuracy of the modelling. The response of all three structures was examined by comparing their ballistic resistance, failure mechanics and energy absorption characteristics. In addition, the parametric study was conducted numerically by changing the face skin thickness, cell length and cell wall thickness to find out their influence on the impact response of all three structures. The results revealed that the hemispherical structures showed higher impact resistance in terms of higher ballistic limit velocity and energy absorption. The ballistic limit of the HSS structure was 14.6% and 36.5% higher than the CSS and FSS structure respectively against hemispherical nosed projectile whereas the corresponding value against conical projectile was 9.9% and 20.6% respectively.

Performance of reinforced concrete composite wall systems under projectile impact

Composite walls consist of two reinforced concrete (RC) walls with or without a filling between them. The use of RC composite walls instead of thick monolithic concrete walls can save material costs significantly. However, it is still unknown if a composite wall system with some granular filling can provide impact resistance comparable to a monolithic RC wall. The objective of this experimental study was to investigate the effect of granular fillings between the two RC walls in improving the impact potential of composite walls and compare the behavior of such walls with that of an equivalent monolithic RC wall. For this purpose, the specimens were prepared to simulate monolithic and composite RC walls. These specimens were tested with a gas gun under single and multiple/repetitive impact loading using hemispherical nose projectiles. The composite walls’ response was then studied and compared with the response of monolithic and no-filling composite walls. Test results and the analysis of the results demonstrate that the idea of using a composite wall system is very promising as the impact response of a composite wall system is much improved than a monolithic wall of the same total thickness and reinforcement. The ballistic limit of the composite wall was also found. In order to predict the ejected mass from a composite wall system, a new analytical model was proposed. There was reasonable agreement between the test results and the prediction.

Numerical investigation on drag characteristics of the truncated hemispherical-nose projectile in vertical water entry

ABSTRACT In this study, the feasibility of the ALE algorithm in analyzing the drag of a rigid truncated hemispherical-nose projectile at the initial stage of vertical water entry is examined. The water entry process is simulated under the conditions of different dilated half-angles of the head plane (DHAHPs) and muzzle velocities (u 0). The drag coefficient is obtained by dimensionless processing of the drag. The maximum (Cd max) drag coefficients of the initial stage are fitted to obtain the generalised impact laws of water entry. The results show that the larger the DHAHP, the smaller is u 0 and the higher is Cd max. The bivariate fitting formula for Cd max of the truncated hemispherical-nose projectile has high prediction accuracy and wide applicability. The average (Cd ave) drag coefficients of the projectile changes significantly after DHAHP of approximately 40°. This change is related to the wet state of the head.

Impact behavior of hybrid-fiber reinforced concrete beams

The impact studies on concrete beams are primarily pertaining to the drop hammer impact, and studies involving projectile impacts on reinforced concrete beams are limited. In this research, the response of hybrid fiber reinforced concrete (HFRC) beams under quasi-static loading and the projectile impact was studied. The HFRC was produced using eight concrete mixes having different proportions and combinations of three fiber types (viz. polypropylene, steel, and Kevlar). The HFRC mixes had a total fiber volume fraction of 1.2% and 1.4%. In addition, plain concrete was used as a control. The beams were tested under the impact of hemispherical nose projectile at varying strike velocities. The projectile strike velocity was increased till the perforation of beams. The main flexural reinforcement in beams was provided on the back face. In order to assess the punching resistance of beams, the beams were tested under quasi-static punching load applied using the same projectile employed in impact tests. The use of hybrid fibers improved beams’ quasi-static punching resistance in terms of energy absorption and load–displacement behavior. The hybrid fibers also improved the impact response of beams by reducing damage levels, increasing perforation velocity, and reducing ejected mass. By modifying the earlier proposed model for slabs, the ballistic limit of HFRC beams is also predicted.

Effect of projectile nose on high‐velocity impact behavior of fiber metal laminates

AbstractFiber metal laminates (FMLs) are a class of hybrid materials consisting of several thin metal layers bonded by layers of composite material. In the present study, the ballistic limit, absorbed energy, specific perforation energy and failure mechanism of FML 2/1 (Al/GFRE/Al) and FML 3/2 (Al/GFRE/Al/GFRE/Al) are numerically and experimentally studied under the high‐velocity impact loading using a single‐stage light gas gun. In addition, the ballistic behavior of FML 2/1 and FML 3/2 is investigated using three different projectile nose geometries. Numerical simulation of the ballistic tests was performed to determine the residual velocity and the FML panel failure mechanism by using AUTODYN. The results indicated that the highest ballistic limit for FML 2/1 and FML 3/2 was obtained for the conical nosed projectile and the ballistic limit of FML 3/2 was 75.63% higher than FML 2/1. Although the FML 3/2 thickness is ~67% higher than FML 2/1, the specific perforation energy of FML 3/2 is improved by 72.51%, 55.26%, and 89.22% compared to FML 2/1 for blunt, hemispherical, and conical nosed projectiles, respectively.

Experimental and numerical study on the ballistic resistance of 6061-T651 aluminum alloy thin plates struck by different nose shapes of projectiles

The aim of the present paper is to study the effect of shapes of projectile nose on the ballistic resistance of 6061-T651 aluminum alloy thin plates, and to evaluate the effect of Lode angle dependent fracture criterion when predicting the ballistic resistance of 6061-T651 aluminum alloy thin plates struck by projectiles with different nose shapes through finite element (FE) simulations. To this end, the ballistic impact tests are firstly conducted using different nose shapes of projectiles. Ballistic limit velocities (BLVs) of different projectile-plate pairs considered are calculated by using initial versus residual velocity data obtained from the experiments. It can be found that the BLV of spherical projectile is the highest, followed by ogival-, blunt- and hemispherical-nosed projectiles. Subsequently, a 3D FE model corresponding to the test is built by ABAQUS/Explicit software and then they are adopted to predict the ballistic resistance of the plate. In these simulations modified Johnson-Cook (MJC) strength model accompanied with either the Lode angle independent and slightly modified Johnson-Cook (MJC) fracture criterion or the Lode angle dependent and modified Mohr-Coulomb (MMC) fracture criterion are adopted to describe plate material properties. Finally, the predicted ballistic resistance of the plates is compared with those observed in the experiments. The numerical predictions of the plate struck by different nose shapes of projectiles show that the BLV predicted by Lode angle dependent MMC fracture criterion is more accurate for spherical and ogival-nosed projectile, while the BLV predicted by Lode angle independent MJC fracture criterion is more accurate for blunt- and hemispherical-nosed projectile. In addition, the results show that the Lode angle's effect is related to the curvature radius of the nose shape of projectile, i.e., the Lode angle's effect decreases with the increase of the curvature radius.

Experimental and Numerical Investigation of the Effect of Projectile Nose Shape on the Deformation and Energy Dissipation Mechanisms of the Ultra-High Molecular Weight Polyethylene (UHMWPE) Composite.

The effect of projectile nose shape on the ballistic performance of the ultra-high molecular weight polyethylene (UHMWPE) composite was studied through experiments and simulations. Eight projectiles such as conical, flat, hemispherical, and ogival nose projectiles were used in this study. The deformation process, failure mechanisms, and the specific energy absorption (SEA) ability were systematically investigated for analyzing the ballistic responses on the projectile and the UHMWPE composite. The results showed that the projectile nose shape could invoke different penetration mechanisms on the composite. The sharper nose projectile tended to shear through the laminate, causing localized damage zone on the composite. For the blunt nose projectile penetration, the primary deformation features were the combination of shear plugging, tensile deformation, and large area delamination. The maximum value of specific energy absorption (SEA) was 290 J/(kg/m2) for the flat nose projectile penetration, about 3.8 times higher than that for the 30° conical nose projectile. Furthermore, a ballistic resistance analytical model was built based on the cavity expansion theory to predict the energy absorption ability of the UHMWPE composite. The model exhibited a good match between the ballistic resistance curves in simulations with the SEA ability of the UHMWPE composite in experiments.

Energy dissipation characteristics of single curvature metallic shells subjected to ballistic impact

The impact resistance of single curvature semi-cylindrical shell targets of aluminum 1100-H12 was explored against hard steel cylindrical projectiles. Experimental as well as numerical investigations were carried out to observe the performance of shell targets against ogive, conical, blunt and hemispherical nosed projectiles. Effect of oblique impact was studied on the ballistic performance of the shell targets at 0 (normal), 15 and 30° obliquity. Further, the impact performance of 2 mm thick monolithic and in-contact layered targets of equivalent thickness was evaluated and compared. The projectiles were driven by a pneumatic air gun and the projectile flight path was captured with a high-speed camera. The experimental results obtained in terms of incidence and residual velocities, and deformation profile of the targets, were validated with the numerical analyses conducted in ABAQUS/Explicit solver. Johnson-Cook constitutive strength and damage material model was employed to simulate the deformation and damage evolution in the targets. The ballistic performance of both monolithic and layered targets impacted at oblique incidence, was compared in terms of ballistic limits, failure mechanisms, local and global plastic deformations and plastic strain energy absorbed in radial, circumferential, axial and shear deformation modes. The in-contact layered shell targets exhibited significantly higher impact resistance than the monolithic targets against all projectiles. Target configurations impacted at oblique incidence with conical and ogive nosed projectiles showed increase in global deformation, while, opposite behaviour was observed in case of blunt and hemispherical nosed projectiles. The plastic strain energy absorbed in various deformation modes correlated with the failure patterns observed in the target material during ballistic impact.

Energy absorption characteristic of sandwich shell structure against conical and hemispherical nose projectile

Present study addresses the ballistic performance and energy absorption behaviour of the hemispherical sandwich shell structure having hexagonal honeycomb core against conical and hemispherical nosed projectile. The sandwich shell had two face sheet of radius 100 and 80 mm for outer and inner shells respectively, whereas for the honeycomb core cell thickness 0.05 mm, cell size 3.2 mm and core height 20 mm were considered. Al −1100 H12 was used for both the shell, whereas for the honeycomb core Al − 3003 H18 was employed. The projectiles of diameter 19 mm, length 50.8 mm and mass 52.5 g were hit on the crown of the sandwich shell. The experiments were performed using the pneumatic gun, whereas the ABAQUS/explicit solver was used for numerical simulations. The response of the sandwich shell was studied in terms of ballistic limit, residual velocity, failure modes and energy absorption by the sandwich structure. Numerical study further extended to perform parametric studies to investigate the effect of the face sheet thickness, core cell size and cell wall thickness on the response of the sandwich shell against conical and hemispherical projectile impact. The conical projectile required less energy for perforation as compared to the hemispherical nosed projectile.

Ballistic performance of monolithic and double layered thin-metallic hemispherical shells at normal and oblique impact

The present study discusses experimental and numerical investigations on the ballistic performance of aluminum 1100-H12 hemispherical shell targets of 150 mm diameter against 19 mm diameter cylindrical steel projectiles. The influence of nose profile of the projectiles on the impact resistance of the targets, was observed by varying the nose geometry to ogive, blunt, conical and hemispherical shapes. Effect of normal as well as oblique impact on the failure mechanisms and perforation process of shells was studied at 0 (normal), 15 and 30° angle from the normal incidence path. Further, the ballistic performance of two target configurations, viz. 2 mm thick monolithic and double layered in-contact shell targets was investigated and compared within the configurations. The finite element analysis of the ballistic impact on shell targets was done in ABAQUS/Explicit solver by employing the Johnson – Cook constitutive strength and damage model for deformable target material, whereas all the projectiles were assumed as rigid body. The ballistic performance of both shell target configurations against oblique impacts with different projectiles was evaluated and compared in terms of ballistic limit, local and global deformations, failure mechanisms and plastic work done in radial, polar, meridional and shear deformations. The obtained experimental results were then compared with numerical simulations and found in good corroboration. It was observed that both monolithic and layered shell targets showed highest ballistic resistance against hemispherical nosed projectile. For all the projectiles, layered shell targets displayed higher energy dissipation than monolithic targets.

Experimental and numerical investigations on the behavior of thin metallic plate targets subjected to ballistic impact

In this study, the description of energy absorption capacity in different deformation modes in the perforation of thin metallic aluminum 1100-H12 targets is presented. The targets were impacted with 19 mm diameter hard steel cylindrical projectiles of varying nose profiles, viz. ogive, blunt, conical and hemispherical shape. Effect of oblique impact on the perforation behavior of 255 mm diameter circular plate targets was studied at 0 (normal), 15 and 30° angles from the incidence line. The ballistic performance of two different configurations of plate targets, viz. monolithic target of 2 mm thickness and in-contact double layered target of equivalent thickness (2 × 1 mm) was also investigated and compared. The numerical simulations were executed using Johnson-Cook elasto-viscoplastic material model for the targets in ABAQUS/Explicit solver and the results were corroborated with the experimental observations. The ballistic performance of the targets against different nose shaped projectiles, was evaluated and compared in terms of ballistic limit velocities, local and global deformations in the target, failure mechanisms and plastic work done in various deformation modes involved in the impact process. It was observed that the ballistic limit for all targets was increased with obliquity, except for targets impacted with blunt nose projectile. The energy absorbed in different deformation modes corroborated with the failure mechanisms involved in the target during perforation. Both target configurations showed the highest ballistic resistance for hemispherical nosed projectile.

Numerical Study on Ballistic Resistance of Thin Aluminium Plate Subjected to Variable Diameter Projectile Impacts

The ballistic resistance of a thin aluminium plate was investigated against rigid hemispherical nosed projectile impact. The target span was varied as 68 mm, 100 mm, 150 mm and impacted normally by 19 mm diameter hemispherical nosed projectile. The residual velocity and ballistic limit velocity obtained from the numerical results using nonlinear finite element code LS-DYNA is compared with the experimental results available in the literature. Further, parametric study has been carried out for different projectile diameter with the same target span and validated with Recht and Ipson’s model. The ballistic limit has been decreasing with decrease in projectile diameter and it is also observed that ballistic limit of the target increases with increase in target span diameter.

High-velocity impact behavior of sandwich structures with AL faces and foam cores—Experimental and numerical study

In this research, the effect of layering of the foam core of sandwich structures with aluminum face-sheets (AL-1050) and also arrangements of these layers on the ballistic resistance of the structures under high-velocity impact were investigated experimentally and numerically. Three single-layer core sandwich structures and four sandwich structures with four-layer core were considered with a total fixed volume (90 ⁎ 90 ⁎ 63 mm3). These structures were impacted by a hemispherical nose cylindrical steel projectile of 20 mm length and 8 mm diameter. The impact velocity range was chosen from 188.7 to 322.6 m/s. The results of this study revealed that, considering constant core mass and total thickness, the core layering increases the ballistic limit velocity of the sandwich structures, so that the ballistic limit velocity of the sandwich structures with four-layer core, with different arrangements of layers, compared to the single-layer core structure is 5 to 8 percent higher, on average. Also, experimental and numerical results are in good agreement. In this research, the effect of parameters such as the sandwich structure core, the thickness of the face-sheets, the projectile nose geometry, the projectile diameter and mass on the ballistic limit velocity were investigated. The study showed that the removal of the core from the sandwich structure led to a 32% reduction in ballistic limit velocity. Increasing the thickness of the back face-sheet (with the constant total thickness of the two face-sheets) increases the ballistic limit velocity by more than 6%. Compared to flat nose projectile, the ballistic limit velocity of a hemispherical nose and conical nose projectiles are respectively 9.5 and 15.6% less. Considering a constant projectile mass, with an increase of 12.5 and 25% in its diameter, the ballistic limit velocity was increased by 6.5 and 14.4%, respectively, and by decreasing the diameter by 5 and 10%, the ballistic limit velocity dropped 7.9% and 13.5%, respectively. Assuming a fixed initial kinetic energy, the increase in the mass of the projectile also reduced the ballistic limit velocity, so that by increasing the 14 and 46.1% of the projectile mass, the ballistic limit velocity was reduced by 8.5 and 18.3%, respectively.

Finite Element Simulation of Tensile Preload Effects on High Velocity Impact Behavior of Fiber Metal Laminates

As primary structures and protective structures, fiber metal laminates (FMLs) in practical application are always in preload states before possible impact damage threats. In this work, a nonlinear finite element (FE) model is developed to study the impact damage scenario where tensile preloaded FMLs are impacted by a hemispherical nose projectile at high velocities. In the modeling, the intra-layer damage in aluminum sheets and composite laminates and the delamination between adjacent plies are entirely included. The FE model is verified with available experimental results in non-preload condition and then applied to predict the high velocity impact behavior in uniaxial and biaxial tensile preload cases. The ballistic performance and damage response of representative FMLs with different preloads and impact velocities are discussed and analyzed in detail. The numerical results and modeling strategy here provides applicable reference for preloaded impact issues in other FMLs.