Papers by Keyword: High Velocity Impact

Abstract: Recently, ceramics and metal-armed structures have been replaced by ceramics combined with ultra-high molecular weight polyethylene (UHMWPE) composite laminated structures for NIJ level III and level IV body armor applications. This shift is due to the superior specific energy absorption capabilities of the ceramics/UHMWPE composites compared to traditional ceramics and metal armor; however, it comes at a higher cost. Manufacturing body armor that offers higher specific energy absorption at a lower cost is challenging. As the thickness of UHMWPE increases, both the specific energy absorption and the overall cost of the body armor increase. Additionally, there is limited experimental data to evaluate the thickness of ceramics and UHMWPE to explore the performance of NIJ level III body armor, indicating that further research is needed. In this study, six different types of ballistic plate configurations were manufactured. Following that, high velocity impact tests were conducted to investigate the effects of front and back layer thicknesses of UHMWPE (Type 1 to Type 3 plates), the effects of foam material (Type 4 plate), and the effects of different thicknesses of boron carbide (B₄C) ceramic strike face (Type 5 and Type 6 plates) on the back face signature (BFS) of the ballistic plate. It was found that the BFS of Type 5 and Type 6 ballistic plate configurations is lower by 12% and 8.5%, respectively, compared with that of the Type 4 UHMWPE/polyvinyl chloride low-density foam ballistic plate. However, the Type 5 option is cost-effective and easy to manufacture, making it the preferred choice over the Type 6 variant.

Abstract: This article focuses on the Finite Element (FE) analysis of the ballistic performance of the polymer composites consisting of natural rubber (NR), glass-epoxy (GE) and glass-rubber-epoxy (GRE) sandwich of different thicknesses (3, 6 and 9 mm) under the impact of the conical nose projectile for a velocity variation of (180, 220 and 260 m / s). FE modeling was carried out in direction to forecast the energy absorption, ballistic limit velocity and failure damage mode of the target materail. The significant influence of thickness, interlayer and sandwiching effect was studied: the lowest ballistic limit was obtained for 3 mm thick GE. Energy absorption capacity of GRE sandwich was highest among the natural rubber and GE. In future, the work can be extended for the experimental validation purpose, so that these polymer composite materials could be utilized to defence sector for bullet-proofing.

Abstract: Sandwich structures based on Fibre Reinforced Polymer (FRP) facesheet skins bonded with low density aluminium foam core are increasing in use in aerospace and marine industries. These structures are very sensitive to high velocity impact during the service. Therefore, it is necessary to study the energy absorption of the structures to ensure the reliability and safety in use. Experimental investigation of these transient events is expensive and time-consuming, and nowadays the use of numerical approaches is on the increase. Hence, the purpose of this paper is to develop a numerical model of sandwich panels with aluminium foam as a core and Glass, Carbon and Kevlar Fibre Reinforced polymer composite as faceplate, subjected to high velocity impact using ABAQUS/Explicit. The influence of individual elements of the sandwich panel on the energy absorption of the structures subjected to high velocity impact loading was analysed. Selection of suitable constitutive models and erosion criterion for the damage were discussed. The numerical models were validated with experimental data obtained from the scientific literature. Good agreement was obtained between the simulations and the experimental results. The contribution of the face sheet, foam core on the impact behaviour was evaluated by the analysis of the residual velocity, ballistic limit, and damaged area.

Abstract: The Kevlar is an organic high crystalline fiber belonging to the aromatic polyamide family extensively used for its strength. Kevlar fiber posses high cut resistance and flame resistance, hence they have a wide range of application in ballistic and defense ^[2]. This paper investigates how K-149 behaves mechanically under sudden high velocity impact, it also shows which types of Kevlar grade hold the maximum impact stiffness capacity. In addition it also predicts the stress induced on the specimen at the time of impact. The ballistic impact object considered as 9mm standard size bullet used in short gun. The assumed velocity for these cases is 650m/s. The specimens K-149 & k-49 taken to be rectangle with the standard size 50 mm x 50 mm. The computational analysis done on Kevlar 49 & 149 and the results have been compared with the help of the pictorial representation of post processing abaqus results and the best ballistic material can be chosen. This paper also provided the recommended research data to fill the technology gap in defense material science.

Abstract: This paper explains the utilisation of finite element model to analyse the ballistic limit of aluminium alloy 7075-T6 impacted by 8.33 g with 12.5 mm radius rigid spherical projectiles. This numerical study was compared with the results obtained experimentally. During impact, the targets were subjected to either non- or uniaxial- pretension and the projectile travelled horizontally to the target. It was observed that pretensioned targets were more vulnerable, which reduced the ballistic limit. The existence of harmful failures owing to pretension impact was ascertained and compared with the non-pretension targets.

Abstract: Cubic-shaped specimens and hat-shaped specimens were used to investigate ASBs formed in Mg-12Gd-3Y-0.5Zr magnesium alloy under different initial strain rate impact. It shows that no adiabatic shear bands (ASBs) is observed in micro-structure of cubic-shaped specimens by scanning electron microscope (SEM) , but obvious ASBs can be observed in hat-shaped specimens. Johnson-Cook model based on thermoviscoplasticity constitutive relation was used to simulate internal stress distribution and fracture mode, and it indicated that the result of failure analysis from specimens under high velocity impact tests was the same as that obtained by computer simulation.

Abstract: This study presents the local damage of ultra high strength fiber reinforced concrete plates. Impact test of the reinforced concrete plates using two different short fibers are conducted to examine the failure behavior and impact resistant performance. Material models are discussed and proposed by simulating the high speed tri-compressive and uni-tensile tests. Numerical simulations of the impact tests are carried out. Numerical results show good agreements with the test results.

Abstract: A finite element model is developed in this paper to simulate the perforation of aluminium foam sandwich panels subjected to high velocity impact using the commercial finite element analysis software LS-DYNA. The aluminum foam core is governed by the material model of crushable foam materials, while both aluminium alloy face sheets are modeled with the simplified Johnson-Cook material model. A non-linear cohesive contact model is employed to simulate failure between adjacent layers, and an erosion contact model is used to define contact between bullets and panels. All components in the model are meshed with 3D solid element SOLID 164. The developed finite element model is used to simulate the dynamic response of an aluminium foam sandwich panel subjected to projectile impact at velocity ranging from 76 m/s to 187m/s. The relationship between initial velocity and exit velocity of the projectile obtained from numerical modelling agrees well with that obtained from experimental study, demonstrating the effectiveness of the developed finite element model in simulating perforation of sandwich panels subjected to high velocity impact.

Abstract: The 2D axisymmetric smoothed particle hydrodynamics (ASPH) has been adopted to study the perforation of AA5083-H116 aluminum plates with ogive-nose hard steel projectiles. The deceleration history curves of the projectile by the ASPH were presented for three impact conditions. Impact vs. residual velocity curves were constructed and the ballistic limit velocity was determined. The computational residual velocities and the ballistic limit velocities from the ASPH agree well with available experimental data. The study shows that the ASPH is able to emulate the perforation of aluminum plates as observed in the experimental investigations of high velocity impact.

Abstract: This paper presents the ballistic impact study for the non-filled aluminum tank. The objective was to determine the ballistic limit for front tank wall and rear tank wall. The tank was impacted with fragment simulating projectile (FSP) with various velocities range from 239 m/s up to 556 m/s. The aluminum tank was 3 mm thick, 150 mm wide and 750 mm long. The ends of tank were closed with two Polymethyl methacrylate (PMMA) windows which fixed to the tank with four steel bars. The test was conducted at the Science and Technology Research Institute for Defense (STRIDE) Batu Arang, Selangor. The results showed that the ballistic limit for the front tank wall and rear tank wall was 257.7 m/s and 481 m/s, respectively.