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Schematic of target holder setup for impact experiments showing the materials used in the models (see later).
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A pre-stressing technique for improving the ballistic performance of a circular silicon carbide tile has been tested against ø12-mm spherical steel projectile. The confining pre-stress was achieved through a heat-shrunk steel collar and was evaluated through neutron diffraction for the ceramic-collar system. Subsequent ballistic experiments and sim...
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... (2 kgF). All impact velocities were nominally 400 m/s. The target was sandwiched between a thin (~1 mm) soft aluminium alloy cover plate (with an average hardness of 49.8 HV) and rear plate (AA 5005-H34, with an average hardness of 103.3 HV), a steel target fixture is placed in front of the cover plate and bolted to the rear plate as depicted in Fig. 2. The tiles were fixed to the aluminium rear plate and cover plate using Loctite EA E-30CL epoxy resin to retain as much of the ceramic fragments as possible post-impact. Similarly, the steel target fixture was designed to hold the ceramic target in place to reduce any damaged material from the ceramic target detaching, Fig. 2. A ...
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... plate as depicted in Fig. 2. The tiles were fixed to the aluminium rear plate and cover plate using Loctite EA E-30CL epoxy resin to retain as much of the ceramic fragments as possible post-impact. Similarly, the steel target fixture was designed to hold the ceramic target in place to reduce any damaged material from the ceramic target detaching, Fig. 2. A high-speed camera setup was implemented with the Phantom v710 at 30,010 fps to record the perpendicular of the direction of impact. The projectile velocity was recorded by a VMS-2000B Velocimeter (accuracy to ~10 m/s). The impact velocity calculated using the high-speed camera footage matched closely with velocimeter's ...
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... of the scalar damage parameter shows that increased prestress reduces the extent and volume of material in the conoid damage zone as shown in Fig. 12. Also highlighted is the mesh dependence of the solution, as greater mesh refinement provides greater resolution of the crack paths. The fine mesh model shows good qualitative agreement for the confined and ~100 MPa pre-stress, in comparison to the experimental, with radial through-thickness cracking evident for the confined model. The ...
Citations
... The composite target was fixed in a steel frame with a covering plate, with an exposed area of 150 mm × 150 mm. Studies 21,[25][26][27] have shown that lateral constraint and prestress had an important effect on the performance of ballistic ceramics. In order to avoid the interference of above factors on the test results, as shown in Figure 4A, there was an above 3 mm gap between the ceramic side surface and the inner wall of the steel frame, which was filled with expandable polyethylene. ...
Several commonly used ceramics in ballistic protection were compared in terms of ballistic resistance and failure behavior, including alumina (Al2O3), silicon carbide (SiC), boron carbide (B4C), and silicon nitride (Si3N4). Hybrid ceramic ultrahigh molecular weight polyethylene composite armors were impacted by 12.7 mm armor‐piercing incendiary projectiles, with a velocity of around 490 m/s. Moreover, there was a layer of aramid fabric composite covering on the impacted side of the ceramic plate. These composite armors were paneled with four different types of ceramics as faceplates and had the same sizes. The ballistic test results show that B4C ceramic provides the worst protection performance, and SiC provides the best protection performance. The angles of ceramic cones formed by different ceramic plates under the same impact load are different, SiC is the widest and Al2O3 is the narrowest. Numerical simulation shows that several ceramic composite targets have the same resistance to the projectile at the pit stage. The fragment mass was quantified by using the screening method, and the results show that the Schumann distribution is more consistent with the experimental results.
... Although most brittle-fracture models do not accurately describe the nucleation and propagation of cracks and inevitably miss some complex physical phenomena, key features of the impact response of brittle materials can be captured in numerical simulations and the results are illuminating [13][14][15][16][17][18]. These phenomenological models involve some parameters that are not physically based and difficult to determine experimentally; therefore, these parameters are usually modified to match the experimental results. ...
... The velocity measurement system obtained the approximate impact velocities of the projectiles by measuring the times when the projectile passed through two light screens with a distance of 2.0m. The composite targets were fixed in a steel frame with a cover plate to facilitate clamping, shown in Figure 4. Studies have shown that lateral restraint have an obvious effect on the ballistic performance of ceramic (Chi et al., 2015;Hazell et al., 2021;Lundberg et al., 2000;Lynch et al., 2006), but it was not within the research scope of this article. There was a 3mm spacing between the ceramic side and the inner wall of the steel frame to ensure that the composite target would not receive lateral restraint and pre-stress. ...
... Based on the SEM observation of the fragments collected after the test in 3.2.2, it was determined that the fragmentation mode of the core is a brittle fracture. And SiC ceramic was a typical brittle material (Chi et al., 2015;Hazell et al., 2021). The distributions of the fragments of the core and ceramic were fitted by Schuhmann distribution. ...
... However, none of these methods have been widely used beyond the work of their original authors. Preliminary works to relate ceramic pre-stress magnitude to ballistic performance have been conducted in [28] [29], focusing primarily on the influence of pre-stress on crack propagation within the ceramic. In [28] the authors performed reverse ballistic tests using sub-scale tungsten penetrator (2.0 mm diameter, 80/120 mm length). ...
... They identified an initial improvement in dwell performance with increasing pre-stress magnitude, however above ~100 MPa the performance reached a plateau, however sub-scale ceramic armour performance may not translate directly to larger systems [30]. In [29] direct impact tests were performed using 12.0 mm diameter steel spheres against unconfined, confined, and radial pre-stressed ceramic targets. From a single successful shot against each target configuration, the authors found that the radial pre-stress affected the trajectory of the Hertzian cone crack, limiting overall damage and thus proposed to improve ballistic resistance. ...
A series of bare silicon carbide ceramic armour disks were manufactured with high-strength steel containment to induce varying magnitudes of radial pre-stress. The induced radial stresses, ranging from 0 to 900 MPa, were measured via neutron diffraction and verified by comparison with numerical calculations. Four targets of each configuration, referred to as slip-fit, moderate pre-stress, and high pre-stress, were subject to ballistic testing with hemispherical-nose, tungsten heavy alloy long rod projectiles to determine the interface defeat transition velocity. In-situ diagnostics were unsuccessful in aiding the identification of interface defeat, necessitating a reliance on post-mortem assessment. A transition velocity of approx. 1000 m/s was identified for the unstressed target, increasing to approx. 1200 m/s for the pre-stressed configurations. No performance effect was discernible between the moderate (372 MPa) and high (899 MPa) pre-stress configurations, suggesting that an optimal performance may be achieved for lower pre-stress levels (i.e., <372 MPa). The test results were compared with four semi-analytical predictions of interface defeat performance and good agreement was found, albeit with significant range in the model predictions.
A ballistic resistance of hard ceramic combined with aluminum foam sandwich (CAFS) constructions was investigated in this paper. This combination plate is constructed by a front faceplate (FFP), ceramic plates, an aluminum foam (Al-foam) panel, and a rear faceplate (RFP). The material used for the FFP and RFP was heat-treated mild steel with the thicknesses are 5 mm and 3.5 mm, respectively. The ceramic materials to be evaluated are B 4 C, SiC, and Al 2 O 3 . Al-foams were fabricated by varying the stabilizer weight ratio of MgO and Al 2 O 3 . The Al-foams have a porosity of 79.93%–82.57%, a pore diameter of 2.51–2.82 mm, the relative density of 0.17–0.24, and plateau stress of 3.88–6.63 MPa. Ballistic tests were carried out only for aluminum foam sandwich (AFS) construction without ceramics to evaluate the manufacturing effect and to obtain a baseline ballistic plate to be improved. Ballistic tests are conducted by using 5.56 × 45 mm bullet with 50 m shooting range and bullet speed of 929–958 m/s. To validate the damage mode and energy absorption capability of the AFS, a numerical model is constructed. The numerical studies were conducted to investigate the damage mode and energy absorption capabilities of each part. The simulation has a good agreement with the experiment result on the damage mode. This model then to be used to study the effect of the additional hard ceramic layer. An interaction between hard ceramic and AFS is also investigated to get a new insight of the energy absorption mechanism during bullet penetration. A new finding shows that ceramic presses the Al-foam to solidify so that it can increase the energy absorbed by the Al-foam. The ceramic is impacted by a bullet pushing the Al-foam so that it undergoes solidification which leads to increasing absorbed energy.
The failure and fragmentation of monolithic bare alumina 99.5% ceramic target and energy dissipation of steel 4340 projectile have been studied in a series of ballistic experiments carried out, with the incidence velocities in a range, 122–290 m/s. The velocity drop and energy dissipation increased with incidence velocity for 10 mm thick target with damage zone extended upon the whole area of rear face at higher velocities. The ballistic results obtained with the 10 mm thick target have been compared with the ballistic performance of the 5 mm thick target used in a previous study to explore the effects of target thickness on the failure mechanism. A model for the residual velocity of projectile after perforation of the single layered ceramic target has been developed based on the Lambert Jonas model by using the experimental data available for 5 mm and 10 mm thick alumina 99.5% target against 10.9 mm projectile. The residual velocities and damage patterns were reproduced with a reasonable amount of accuracy by a three-dimensional finite element model developed on commercial ABAQUS/CAE. The effect of obliquity and projectile diameter to target thickness ratio (D/T) on ballistic performance has been determined by the numerical simulation model with impact velocity in a range of 300–500 m/s. A spatial variation of ejected fragments velocity at different time steps was plotted to develop a velocity profile for the ceramic fragments coming out of the target. A semi-empirical model has been proposed for residual velocity after perforation of a monolithic ceramic target, relating to the incidence velocity and projectile diameter to target thickness ratio. The monolithic ceramic targets have been investigated for a comparative assessment of energy dissipation by the ceramic layer to eventually design an efficient front layer of a ceramic based composite armour in future studies.
