Browsing by Author "Arifurrahman, Faizal"
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Item Open Access Experimental and numerical study of auxetic sandwich panels on 160 grams of PE4 blast loading(SAGE, 2020-09-30) Arifurrahman, Faizal; Critchley, RichardMines, specifically as Anti-Tank (AT) mines are a significant threat for defence vehicles. While approaches such as v-shaped hulls are currently used to deflect the blast products from such threats, such a solution is not always usable when hull standoff is limited. As such the development of a low profile, energy absorbing solution is desirable. One approach that has potential to achieve these requirements are sandwich panels. While sandwich panel cores can be constructed from various materials, one material of particular interest are auxetics. Auxetic are materials that exhibit a negative Poisson’s ratio. This material has potential to be an efficient an impact energy absorber by increasing stiffness at local deformation by gathering mass at the impact location. This study investigates the effectiveness of novel auxetic core infills alongside three other panel types (monolithic, air gap, polymer foam sandwich) against buried charges. 160 grams of PE4 were buried in 100 mm depth and 500 mm stand off the target. Laser and High Speed Video (HSV) system were used to capture the deflection-time profile and load cell sensors were used to record the loading profile received by the panels. Experimental works were compared with numerical model. Explicit model were generated in LSDYNA software as ‘initial impulse mine’ keyword. The result found that the auxetic and foam core panels were effective in reducing peak structural loading and impulse by up to 33% and 34% respectively. Air-filled panels were the most effective to reduce the deflection of the rear of the plate, however variation between capture methods (HSV and Laser system) were reported, while numerical modelling provided comparable plate deflections responses. When normalised against panel weight, the air filled panels were experimentally the most efficient per unit mass system with the auxetics being the least effective.Item Open Access On the importance of the bullet jacket during the penetration process: reversed-ballistic experimental and numerical study(Springer Verlag, 2020-04-30) Lesmana, Denny; Arifurrahman, Faizal; Hameed, Amer; Appleby-Thomas, Gareth J.; Santosa, Sigit P.The behaviour of exposed and copper-jacketed 12.7 mm En8 steel cores impacting against 5 and 9 mm Armox Advance plates was investigated to determine the significance of the jacket during the penetration. The target plates were accelerated into stationary projectiles (a reversed-ballistic configuration) and the impact was monitored using a multichannel flash X-ray system to gain insight into the interaction of the core target. Numerical simulations were also carried out to compare result with the experimental testing. Explicit numerical software LS-DYNA was used to model the behaviour of the target and the projectile during the impact collision. Fragments of the core and target plate were collected post-shot for analysis. A similar penetration behaviour was observed for both plates, although the post-shot core was shorter after impacting against the 9 mm plate, consistent with enhanced erosion behaviour. The copper jacket protected the core, resulting in greater surface defeat and dwell compared to the unjacketed core. Numerical studies agreed on the cases of projectile impacting the 5 mm and 9 mm target. However, the target fracture cannot be captured. This could be caused by the input of material data and strain rate parameter modelling in LS-DYNA was limited, while the impact phenomenon was high velocity impact that the material exhibits a highstrain rate effect. Overall, the ductile jacket appeared to serve two functions: (1) Absorbing reflected energy during impact, hence cushioning the impact and thereby preserving the core, and (2) constraining or confining the core. In this study, the steel core design and copper jacket has a more complex geometry compared to the simplified steel core designs often applied in several earlier ballistic studies. The captured flash X-rays revealed significantly less erosion in the jacketed cores, agreeing with the post-impact core length measurements.