Composite Projectile Research Articles

Compressive behavior and visco-hyperelastic constitutive of polyurethane elastomer over a wide range of strain rates

Polyurethane elastomers (PUEs) will experience different strain rates in different application scenarios. Therefore, it is of great significance to study the mechanical properties of PUE under a wide range of strain rates and establish a constitutive model that considers strain rates with high accuracy and few parameters. In this study, the quasi-static and dynamic compression tests of two types of PUEs (PUE55 and PUE85) were carried out, and investigated the strain rate effect of the materials. Based on the Mooney-Rivlin hyperelastic model and the Prony series, a compressible visco-hyperelastic constitutive model for PUE was established. Different from the conventional constant relaxation time in Prony series, two relaxation times that vary exponentially with principal stretch were proposed based on the relaxation test to describe the strain rate effect of the material at low and high strain rate respectively. In addition, using the visco-hyperelastic constitutive model to obtain the model inputs of the Simplified rubber/foam model in LS-DYNA, the impact process of the Metal/PUE composite projectile was reproduced under different impact conditions through the finite element simulation. Simulation results verified the visco-hyperelastic model in generating numerical model material parameters and the rationality of the Simplified rubber/foam model in describing PUEs.

Response of aluminium honeycomb sandwich panels under combined shock and impact loading: Experimental and numerical investigations

The performance of sandwich structures against individual shock loading and fragment impact loading has been extensively examined, but little is known about their performance in the presence of simultaneous shock and impact loading. Based on a recently developed composite projectile to simulate combined shock and single fragment impact loading, the performance of aluminum honeycomb core sandwich panels (HCSPs) against combined loading is methodically examined. The achieved results reveal that the combined loading exhibits a synergistic effect compared to the single loading, i.e., increased damage of the sandwich panel and enhanced perforation resistance of the sandwich panel. After that, a three-dimensional finite element simulation is performed to explore the underlying mechanism of the synergistic effect. Numerical analysis indicates that the increased damage is a result of perforation-induced reduction of load-carrying capacity of sandwich panel, while the enhanced perforation resistance is the result of deflecting-induced perforation time delay of the perforation process. Finally, the parametric investigation of sandwich geometries such as asymmetric face sheets, core density, and core height is comprehensively conducted. The gained results reveal that both performance and synergistic effect due to combined loading are sensitive to these parameters.

Impact of composite soft-rigid elastic projectiles: A numerical study.

We study by numerical simulation the impact of a one-dimensional composite projectile, composed of two superposed homogeneous parts, on an infinitely rigid and massive wall. The coefficient of restitution and the contact time are systematically measured as functions of the contrasts of mass and stiffness between the two parts. For purely elastic parts, these quantities show complex trends associated with different dynamics of the deformation waves propagating inside the projectile. A significant portion of the initial kinetic energy can be trapped in the deformation modes: the coefficient of restitution is lowest, about 0.2, when there is a strong stiffness contrast between the two parts and the stiff and soft parts are at the leading and trailing edges of the projectile respectively. In this case, we highlight the presence of multiple bounces, whose number increases as the proportion of the soft part increases. Finally, viscoelastic parts can be implemented in the same numerical framework to successfully recover the results obtained in real composite projectile impact experiments [D'Angelo et al., Phys. Rev. E 103, 053005 (2021)2470-004510.1103/PhysRevE.103.053005].

Computational Analysis of Sandwich Panels with Graded Foam Cores Subjected to Combined Blast and Fragment Impact Loading.

This study aimed to evaluate the performance of sandwich panels with graded foam cores of layered densities against combined blast and fragment impact loading, and to ascertain the optimal gradient of core configuration that would maximize the performance of sandwich panels against combined loading. First, based on a recently developed composite projectile, impact tests of the sandwich panels against simulated combined loading were conducted to provide a benchmark for the computational model. Second, a computational model, based on three-dimensional finite element simulation, was constructed and verified by means of a comparison of the numerically calculated and experimentally measured peak deflections of the back facesheet and the residual velocity of the penetrated fragment. Third, the structural response and energy absorption characteristics were examined, based on numerical simulations. Finally, the optimal gradient of core configuration was explored and numerically examined. The results indicated that the sandwich panel responded in a combined manner involving global deflection, local perforation and perforation hole enlargement. As the impact velocity increased, both the peak deflection of the back facesheet and the residual velocity of the penetrated fragment increased. The front facesheet was found to be the most important sandwich component in consuming the kinetic energy of the combined loading. Thus, the compaction of the foam core would be facilitated by placing the low-density foam at the front side. This would further provide a larger deflecting space for the front facesheet, thus reducing the deflection of the back facesheet. The gradient of core configuration was found to have limited influence on the anti-perforation ability of the sandwich panel. Parametric study indicated that the optimal gradient of foam core configuration was not sensitive to time delay between blast loading and fragment impact loading, but was sensitive to the asymmetrical facesheet of the sandwich panel.

Dynamic performance of ultralight corrugated sandwich plate with FML face-sheets impacted by FSP-foam composite projectile

Ultralight corrugated sandwich constructions have shown great promise as multifunctional structures capable of simultaneous load-bearing, shock mitigation and ballistic resistance, yet little is known about the synergetic effects of combined shock and fragment loadings on their performance. This study presented a combined experimental and numerical investigation of corrugated-core sandwich plate with ultra-high molecular weight polyethylene (UHMWPE) fiber metal laminate (FML) face-sheets subjected to combined shock and fragment impact. The combined loading was achieved using a laboratory-based experimental technique previously proposed by the present authors, i.e., the impact of fragment-foam composite projectile fired from a light gas gun. Corrugated-core sandwich plates with both FML face-sheets and metallic face-sheets were prepared, and their ballistic/blast resistances and deformation/failure modes were characterized experimentally. Three-dimensional finite element simulations were performed and validated to provide further insight into the underlying mechanisms of dynamic responses under combined loading. Compared with the reference sandwich plate with metallic face-sheets, stacking UHMWPE composite sheets into the face-sheets not only maintained the blast-induced deflection but also improved the ballistic limit against the fragment simulation projectile (FSP). The synergetic effect of combined loading could weaken the penetration resistance and increase the permanent deflection, but the tearing cracks caused by combined loading could be significantly inhibited by the use of FML face-sheets. In addition, the impact sequence of foam and fragment affected the ballistic resistance of corrugated-core sandwich plate with FML face-sheets.

Dynamic response of fully-clamped steel plate under laboratory-simulated sequential fragment impact and blast loading

Composite projectile (CP) impact, as a new in-laboratory experimental technique, was further developed to simulate sequential fragment impact and blast loading generated by cased charge explosion. New developments include modification of the equivalent relationships between main loading characteristics from the explosion and the CP impact and the improvement of the experimental setup. Then, it was used to study the dynamic response of a fully-clamped steel plate under simulated sequential fragment impact and blast loading. For comparison, a widely used traditional technique, which decoupled the two load types by generating pressure pulse on the structure with pre-formed holes to simulate the sequential loading, was also employed. Deformation processes, deformation/failure modes, and central deflections of the plates tested using the two different techniques were compared and analyzed. It was found that the traditional technique underestimated the damage caused by sequential fragment impact and pressure pulse: the plate subjected to the CP impact was found to be more susceptible to tearing fractures at high impact velocities. Finite element simulations were subsequently performed and the simulation results were validated against experimental data. The validated FE model was then employed to further evaluate the synergetic effects of sequential fragment simulating projectile (FSP) impact and impulsive loading on the ballistic performance and deformation behavior of the fully-clamped steel plate. Results indicate that while pressure pulse in the sequential loading leads to an enhanced ballistic limit of the plate, FSP impact in the sequential loading causes significant local shear and tensile deformation around the perforation, resulting in plate tearing at a lower impact velocity.

Dynamic response of UHMWPE plates under combined shock and fragment loading

Ultra-high molecular weight polyethylene (UHMWPE) fiber composite has been extensively used to construct lightweight protective structures against ballistic impacts, yet little is known about its performance when subjected to combined blast and fragment impacts. Built upon a recently developed laboratory-scale experimental technique to generate simulated combined loading through the impact of a fragment-foam composite projectile launched from a light gas gun, the dynamic responses of fully-clamped UHMWPE plates subjected to combined loading were characterized experimentally, with corresponding deformation and failure modes compared with those measured with simulated blast loading alone. Subsequently, to explore the underlying physical mechanisms, three-dimensional (3D) numerical simulations with the method of finite elements (FE) were systematically carried out. Numerical predictions compared favorably well with experimental measurements, thus validating the feasibility of the established FE model. Relative to the case of blast loading alone, combined blast and fragment loading led to larger maximum deflections of clamped UHMWPE plates. The position of the FSP in the foam sabot affected significantly the performance of a UHMWPE target, either enhancing or decreasing its ballistic resistance. When the blast loading and fragment impact arrived simultaneously at the target, its ballistic resistance was superior to that achieved when subjected to fragment impact alone, and benefited from the accelerated movement of the target due to simultaneous blast loading.

Study on the Penetration Power of ZrO2 Toughened Al2O3 Ceramic Composite Projectile into Ceramic Composite Armor.

This work aims to improve the penetration ability of a 14.5 mm standard armor-piercing projectile into ceramic/armor steel (Al2O3/RHA) composite armor. To this end, ZrO2 toughened Al2O3(ZTA) is prepared as the material for bullet tips, utilizing in situ solidification injection molding that is realized via ceramic dispersant hydrolytic degradation. The penetration power of ZTA ceramic composite projectile, compared with standard armor, against 15 mm armor steel (RHA) and 30 mm Al2O3/RHA composite armor, is studied by ballistics testing combined with numerical simulation. The Tate theory is optimized and then employed to calculate the penetration depth and bullet core’s residual mass when ZTA ceramic composite projectile penetrates into Al2O3/RHA composite armor. The results show that when penetrating RHA of 15 mm, the penetration area of ZTA ceramic composite projectile into RHA increases by 27.59% and the exit area by 42.93%. While the standard projectile fails to penetrate the 30 mm Al2O3/RHA composite armor, the ZTA ceramic composite armor-piercing projectile succeeds, with the mass loss reduced by 66.67% over the standard one. The ZTA ceramic composite bullet has a better performance than the standard bullet in penetrating RHA and Al2O3/RHA composite armors. The test results, simulation, and theoretical analysis are consistent. This study has practical values for engineering applications to design new ceramic composite bullets.

Study of Impact Characteristics of ZrO2 Ceramic Composite Projectiles on Ceramic Composite Armor.

Exploring new armor-piercing materials is crucial for improving the penetrative ability of projectiles. Based on the process of in situ solidification injection molding through ceramic dispersant hydrolytic degradation, a ZrO2 ceramic material suitable for use as the tip of a 12.7 mm kinetic energy (KE) projectile was prepared. The ZrO2 ceramic tip can be matched with the metal core of a conventional projectile to form a ceramic composite projectile, increasing the damage to the Al2O3 ceramic composite armor. Specifically, the ZrO2 ceramic tip can increase the impact load on the Al2O3 ceramic panel, prolonging the pre-damage phase and reducing the stable penetration phase, shortening the mass erosion time of the metal core compared with a 12.7 mm metal KE projectile tip. The ceramic composite projectile with the ZrO2 ceramic tip has a lower critical penetration velocity than a 12.7 mm metal KE projectile for Al2O3 ceramic composite armor. Furthermore, the residual velocity, residual length, and residual mass of the metal core of the ceramic composite projectile that penetrated the Al2O3 ceramic composite armor are greater than those of a 12.7 mm metal KE projectile.

Dwellings and workspaces at Strandvägen, 5600–5000 cal. BC

This paper describes identified workspaces and the manufacture of slotted bone points at the Late Mesolithic settlement Strandvägen in Motala, in eastern central Sweden. Several dwellings were documented, Dwelling 1 being typically round-oval in shape 9×5.5 meters, with a floor area covering 49.5 m2. Radiocarbon dates fall between approximately 5600-5200cal BC. A combined archaeological record, with lithics and bone artefacts as well as analyses of the osteological assemblage has shown that slotted bone tools with mounted lithic inserts have been produced adjacent of the dwelling. The spatial distribution of bone flakes, microblades, processed resin and slotted artefacts testify to a clearly and delimited craft area near the shoreline of the river Motala Ström. Analyses of the finds, e.g. birch bark resin and prepared bone preforms by direct percussion, also help in reconstructing the stages of manufacturing composite projectile points in this part of Eurasia.

Study on the Penetration Performance of a 5.8 mm Ceramic Composite Projectile.

The penetration ability of a 5.8 mm standard projectile can be improved by inserting a ZrO2 ceramic ball with high hardness, high temperature, and pressure resistance at its head. Thereby, a ceramic composite projectile can be formed. A depth of penetration (DOP) experiment and numerical simulation were conducted under the same condition to study the armor-piercing effectiveness of a standard projectile and ceramic composite projectile on 10 mm Rolled Homogeneous Armor (RHA) and ceramic/Kevlar composite armor, respectively. The results show that both the ceramic composite and standard projectiles penetrated the armor steel target at the same velocity (850 m/s). The perforated areas of the former (φ5 mm & φ2 mm) were 2.32 and 2.16 times larger, respectively, than those of the latter. The residual core masses of these two projectiles (φ5 mm & φ2 mm) were enhanced by 30.45% and 22.23%. Both projectiles penetrated the ceramic/Kevlar composite armor at the same velocity (750 m/s). Compared with the standard projectile, the residual core masses of the ceramic composite one (Ø5 mm & Ø2 mm) were enhanced by 12.4% and 3.6%, respectively. This paper also analyzes the penetration mechanism of the ceramic composite projectile on target plates by calculating its impact pressure. The results show that the ceramic composite projectile outperformed the standard projectile in penetration tests. The research results are instructive in promoting the application of the ZrO2 ceramic composite in an armor-piercing projectile design.

Characterization of Crater Area in a Target Penetrated by a Wf/Zr-Based Amorphous Matrix Composite Projectile.

Tungsten fiber-reinforced Zr41.25Ti13.75Cu12.5Ni10Be22.5 amorphous matrix composites (hereinafter referred to as Wf/Zr-based amorphous matrix composites) are considered as a potential new generation of projectile material, while the penetration behavior of Wf/Zr-based amorphous matrix composites is not fully clear yet. In order to better understand the penetration behavior of this composite material and study its armor-piercing performance, a ballistic experiment was performed and the hardness and microstructure around the crater of a target material were studied. A ballistic experiment was performed with a projectile of Wf/Zr-based amorphous matrix composite and a target of 4043 steel. After the ballistic experiment, the target was cut through the crater using a wire cutting machine into a sample with size 150 mm × 40 mm × 20 mm, which was later polished by different types of sandpaper. The micro-hardness was analyzed in a micro-hardness tester, and the microstructure was observed by SEM. According to this study, three layers were identified in the direction lateral to the crater, consisting of a martensite layer, a deformation strengthening layer, and the original structure layer. Moreover, the martensite layer initially thickened and then thinned in the direction longitudinal to the crater.

Penetration Behavior of Wp/Zr-based Amorphous Matrix Composite

The penetration ability and penetration behavior of 50% Wp/Zr41.2Ti13.8Cu12.5Ni10Be22.5 amorphous matrix composite were studied through penetration test and microtopography observation. It is concluded that: the composite projectile shows self-sharpening behavior when penetrating 30CrMnMo steel target and 6061 aluminum target, especially after penetration of the aluminum target, the phenomenon of self-sharpening is obvious. 50% W particles added greatly improves the penetration performance of the composite. In the process of high-speed collision between the composite projectile and the target, the high temperature causes the amorphous alloy Zr41.2Ti13.8Cu12.5Ni10Be22.5 with low melting point to melt and cover on the surface of the crater.

A laboratory experimental technique for simulating combined blast and impact loading

A novel composite projectile is put forward to simulate combined blast and single fragment impact loading, which is comprised of a cylindrical aluminum foam projectile embedded with a fragment simulation projectile (FSP). Comparison between cased explosive and composite projectile in terms of the generated combined loading shows that the composite projectile technique is theoretical feasible. Experimental tests for normal impact of the composite projectile on clamped plates are carried out. Results show that the proposed composite projectile can induce both blast-induced deflection and fragment-induced perforation on the clamped plate. The arrival time interval between blast and fragment has significant influence on the extent of induced damage on the plate and the residual FSP velocity. Numerical simulations with the method of finite elements are carried out to provide further insight into the interaction between the composite projectile and clamped plate, and to explain observations and measurements in experiments. The present study reveals a new synergetic effect of combined blast and single fragment impact loading on clamped plate: arrival time interval between blast and impact loading affects significantly the residual velocity of the FSP.

Gluon emission at small longitudinal momenta in the QCD effective action approach

In the framework of the QCD effective action the vertices of gluon emission in interaction of reggeons are studied in the limit of small longitudinal momenta of the emitted gluon. It is found that the vertices drastically simplify in this limit, so that the gluon becomes emitted from a single reggeon coupled to the projectile and target via multireggeon vertices. The contribution from this kinematical region is studied for double and 2 times 2 elementary collisions inside the composite projectile and target.

Spacetime picture of baryon stopping in the color-glass condensate

We discuss baryon stopping in the Color Glass Condensate description of high energy scattering. We consider the scattering of a distribution of valence quarks on an ultra-relativistic sheet of colored charge. We compute the distribution of scattered quarks from a composite projectile, and calculate the baryon currents before and after the collisions and on an event by event basis. We obtain simple analytic estimates of the baryon number compression and rapidity shifts, which in the idealized case of plane wave scattering, produce results that agree with considerations of Anishetty-Koehler-McLerran.

Density distributions, form factors and reaction cross sections for exotic 11Be and 15C nuclei

The ground state proton, neutron and matter densities of exotic 11Be and 15C nuclei are studied by means of the TFSM and BCM. In TFSM, the calculations are based on using different model spaces for the core and the valence (halo) neutron. Besides single particle harmonic oscillator wave functions are employed with two different size parameters Bc and Bv. In BCM, the halo nucleus is considered as a composite projectile consisting of core and valence clusters bounded in a state of relative motion. The internal densities of the clusters are described by single particle Gaussian wave functions.
 Elastic electron scattering proton form factors for these exotic nuclei are analyzed via the plane wave born approximation (PWBA). As the calculations in the BCM do not distinguish between protons and neutrons, the calculations of the proton form factors are restricted only by the TFSM.
 The reaction cross sections for these exotic nuclei are studied by means of the Glauber model with an optical limit approximation using the ground state densities of the projectile and target, where these densities are described by single Gaussian functions. The calculated reaction cross sections at high energy are in agreement with the experimental data.

非晶复合材料高速侵彻下反喷碎片的微观组织和侵彻热效应初步分析

非晶复合材料高速侵彻下反喷碎片的微观组织和侵彻热效应初步分析

On the shape of things: A geometric morphometrics approach to investigate Aurignacian group membership

The manufacture of composite projectile technology requires the production and assemblage of tightly fitted parts designed to fulfill a number of distinct functions. Each part combines a number of techno-functional units, and various processes may be responsible for the shape variability of these units. In order to investigate the relative contribution of each process to the overall variability of a projectile implement, one must identify the point of demarcation between its techno-functional units. In the present paper, the concept of shape modularity is introduced to precisely identify this locus. The application of geometric morphometrics and shape modularity to the study of two Aurignacian osseous projectile point types, i.e., split- and massive-based points, reveals interesting patterns. On both types, the maximum width delimits the distal and proximal techno-functional units of these objects. When focusing on the morphometric variability and the geographic distribution of the implements' proximal unit, the eight shapes identified for split-based points are found over vast regions of Europe. On the other hand, the two proximal shapes defined for massive-based points show a pattern of local, or regional, aggregation. These proximal shapes were likely considered fit for hafting and hunting by the prehistoric populations who reproduced them, and they are interpreted as a proxy for the socially shared rules of production that guided the manufacture of these tool types. They could therefore be used in future studies that aim to identify group membership amongst the Aurignacian metapopulation and the extent of their interactions.

Experimental study on the penetration effect of ceramics composite projectile on ceramic / A3 steel compound targets

Abstract In order to improve the penetration of projectiles into ceramic composite armors, the nose of 30 mm standard projectile was replaced by a toughened ceramic nose, and the performance of ceramic-nose projectiles penetrating into ceramic/A3 steel composite targets has been experimentally researched. According to impact dynamics theory,, the performances of 30 mm ceramic-nose projectile and 30 mm standard projectile penetrating into the ceramic/A3 steel composite targets were analyzed and compared using DOP method, especially focusing on the effects made by different nose structures and materials. The aperture and depth of perforation of projectile into the armor plates as well as the residual mass of bullet core under the same conditions were comparatively analyzed. A numerical simulation was built and computed by ANSYS/LS-DYNA. Based on the simulated results, the penetration performance was further analyzed in terms of the residual mass of bullet core. The results show that the ceramic nose has a great effect on the protection of bullet core.