Review Penggunaan Komposit Serat Fiber pada Uji Balistik untuk Peralatan Pelindung Personel

Dalam konteks militer modern, istilah pelindung personel meliputi pelindung badan (rompi yang melindungi torso), helm (melindungi cranium), pelindung wajah dan mata (terutama kacamata dan goggle), perlengkapan Explosive Ordnance Disposal (EOD), dan pelindung balistik. Sejak Perang Dunia I, tentara yang menjadi korban akibat pecahan fragmen dan peluru telah membawa institusi pertahanan dan peneliti untuk mengembangkan pelindung dan prosedur pengujian yang mampu menangkal ancaman proyektil balistik dan dampak ledakan. Pengurangan masa peralatan dan peningkatan level perlindungan menjadi tujuan utama desain body armor. Penelitian dan pengembangan telah dilakukan untuk mendapatkan material atau konfigurasi struktur yang dapat menyerap energy dari impak balistik. Serat fiber adalah salah satu material yang saat ini diteliti menggunakan berbagai metode dan simulasi. Serat fiber dalam bentuk tekstil dan telah dikembangkan untuk respon dari material dan armour pada beban impak balistik. Pengembangan tersebut bertujuan untuk mengurangi angka kejadian dan juga memberikan kenyaman bagi personel selama bertugas. Penggunaan komposit serat fiber memiliki banyak keunggulan bagi personel diantaranya fleksibilitas armor, pengurangan masa total armor, meningkatkan level perlindungan dan meningkatkan factor ergonomis selama penggunaan armor.Kata Kunci: Komposit Serat Fiber, body armour, less weight, protection

The Applications of Auxetic Material

To date, increasing structural efficiency has become a main objective in material science and engineering. One focus is an auxetic material with a unique characteristic obtained by fabricating cellular forms. With its higher strength-to-weight ratio, auxetic is becoming popular in the real-world to produce products that are light but more durable. This study examines potential application of auxetic compared to that of conventional material

Experimental and numerical study of auxetic sandwich panels on 160 grams of PE4 blast loading

Mines, 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

On the importance of the bullet jacket during the penetration process: Reversed-ballistic experimental and numerical study

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

Structural Lattice Topology and Material Optimization for Battery Protection in Electric Vehicles Subjected to Ground Impact Using Artificial Neural Networks and Genetic Algorithms

A critical external interference that often appears to pose a safety issue in rechargeable energy storage systems (RESS) for electric vehicles (EV) is ground impact due to stone impingement. This study aims to propose the new concept of the sandwich for structural battery protection using a lattice structure configuration for electric vehicle applications. The protective geometry consists of two layers of a twisted-octet lattice structure. The appropriate lattice structure was selected through topology and material optimization using an artificial neural network (ANN), genetic algorithms (GA), and multi-objective optimization with technique for order of preference by similarity to ideal solution (TOPSIS) methods. The optimization variables are the lattice structure relative density, ρ¯, angle, θ, and strength of the materials, σy. Numerical simulations were used to model the dynamic impact loading on the structures due to a conical stone mass of 0.77 kg traveling at 162 km/h. The two-layer lattice structure configuration appears to be suitable for the purposes of RESS protection. The optimum configuration for battery protection is a lattice structure with an angle of 66°, relative density of 0.8, and yield strength of 41 MPa. This optimum configuration can satisfy the safety threshold of battery-shortening deformation. Therefore, the proposed lattice structure configuration can potentially be implemented for electric vehicle applications to protect the battery from ground impact

Frame modal analysis for an electric three-wheel vehicle

The alternative electric vehicle for delivery (E-Trike) is a developing three-wheel electric vehicle for goods delivery. Small size and its three-wheel mobility are required for flexible manoeuvrability on urban space due to traffic, parking and alley road. In this study, three different Alpha frames (Alpha-0, Alpha-1, and Alpha-2) of E-Trike vehicle are analysed using numerical simulation LS-DYNA. This study is conducted to obtain the modal response E-Trike vehicle. Eigenvalues of dynamics properties are investigated to avoid a resonance on excitation frequency. LS-DYNA implicit simulation used for simulating quadrangular shell element for the surface geometry of the frames. Boundary conditions are applied to the steering and suspension joints represent the real field. The result shows the amplitudes and the natural frequencies of Alpha frames. Bending mode and torsion mode can be determined. Based on the simulation, there is a pattern of vibration modes. Alpha-2 which is the latest version of three configurations has better response on vibration modes. There is about 3% reduction of vibration amplitude at Alpha-2 than Alpha-0 and Alpha-1. Natural frequency response for each mode occurs at similar range. Furthermore, a shifted natural frequency of Alpha-2 combination mode occurs due to addition of the stretched frame