Assessment of the mechanical properties of different textile materials used for outer shell of bulletproof vest: woven fabrics for military applications

Purpose This paper aims to investigate the performance of four different textile materials used as an outer shell of the bulletproof vest. Design/methodology/approach In this paper, four different textile materials were used, polyurethane treatment was applied as a surface coating for the woven samples. Mechanical properties were conducted for all samples; scanning electron microscope and X-ray energy disperse spectroscopy were executed to show the surface morphology of samples and the chemical composition of the coating material. Findings One-way ANOVA was used to statistically analyse the results, which proved that all variables were highly significantly affected by using different textile materials, despite the stiffness variable being not significantly affected by textile materials. An overall evaluation was done using radar chart, demonstrated that Cordura material accomplished the best functional performance, using two types of calibres 7.62 × 54 mild steel core and 7.62 × 54 armour piercing incendiary; the common mechanism was localized burn because of the incendiary effect of the projectile in addition to tearing mechanism starting from inside because of penetration effect of the steel core. Originality/value This work was addressed to analyse the impact of using four different materials on its performance as the outer shell of bulletproof vest to achieve the desired degree of protection.

Probing Gas Kinematics and PDR Structure around O-type Stars in the Sh 2-305 H ii Region

We report an observational study of the Galactic H ii region Sh 2-305/S305 using the [C ii] 158 μm line data, which are used to examine the gas dynamics and structure of photodissociation regions. The integrated [C ii] emission map at [39.4, 49.5] km s−1 spatially traces two shell-like structures (i.e., inner and outer neutral shells) having a total mass of ∼565 M ⊙. The inner neutral shell encompasses an O9.5V star at its center and has a compact ring-like appearance. However, the outer shell is seen with more extended and diffuse [C ii] emission, hosting an O8.5V star at its center, and surrounds the inner neutral shell. The velocity channel maps and position–velocity diagrams confirm the presence of a compact [C ii] shell embedded in the diffuse outer shell, and both the shells seem to expand with v exp ∼ 1.3 km s−1. The outer shell appears to be older than the inner shell, hinting that these shells are formed sequentially. The [C ii] profiles are examined toward S305, which are either double peaked or blue skewed and have the brighter redshifted component. The redshifted and blueshifted components spatially trace the inner and outer neutral shell geometry, respectively. The ionized, neutral, and molecular zones in S305 are seen adjacent to one another around the O-type stars. The regularly spaced dense molecular and dust clumps (mass ∼10–103 M ⊙) are investigated around the neutral shells, which might have originated as a result of gravitational instability in the shell of collected materials.

Materials for Outer Shell of 1.170 GWh (1.00669 Kilo Ton TNT) Fusion Device - Weight Basis

With recent developments in fusion engineering, interest has sparked in development of fusion devices for deterrent. Enormous amount of energy generated by combining two light nuclei could be contained and manipulated at will to trigger and accelerate micro explosions (from shock wave, x-rays or ion beam focusing) which finally result in full scale blast. Materials required to make such device are critical. They must possess high strength, high hardness, ductility, formability, drawability, and anisotropic properties. High entropy alloys (HEA) are new class of materials which nicely fulfils this requirement. Essentially, they are solid solutions of multi principal elements (usually > 5) eliminating the need of base metal as in conventional alloys. This gives them many unique properties which may be tailored at will (heat treatment, cold rolling, precipitation, irradiation). They also exhibit excellent directional properties with formation of distinct bands along certain preferred crystallographic planes even in hexagonal close packed structures. These anisotropic properties are strong function of rolling, working, or forging (swaging) direction and can be utilized to benefit. This study encompasses making outer shell of a typical fusion device selected on the basis of the weight, which is a function of area of pay load bay of carrier aircraft.

Study of the Role of Void and Residual Silicon Dioxide on the Electrochemical Performance of Silicon Nanoparticles Encapsulated by Graphene

Silicon nanoparticles are used to enhance the anode specific capacity for the lithium-ion cell technology. Due to the mechanical deficiencies of silicon during lithiation and delithiation, one of the many strategies that have been proposed consists of enwrapping the silicon nanoparticles with graphene and creating a void area between them so as to accommodate the large volume changes that occur in the silicon nanoparticle. This work aims to investigate the electrochemical performance and the associated kinetics of the hollow outer shell nanoparticles. To this end, we prepared hollow outer shell silicon nanoparticles (nps) enwrapped with graphene by using thermally grown silicon dioxide as a sacrificial layer, ball milling to enwrap silicon particles with graphene and hydro fluorine (HF) to etch the sacrificial SiO2 layer. In addition, in order to offer a wider vision on the electrochemical behavior of the hollow outer shell Si nps, we also prepared all the possible in-between process stages of nps and corresponding electrodes (i.e., bare Si nps, bare Si nps enwrapped with graphene, Si/SiO2 nps and Si/SiO2 nps enwrapped with graphene). The morphology of all particles revealed the existence of graphene encapsulation, void, and a residual layer of silicon dioxide depending on the process of each nanoparticle. Corresponding electrodes were prepared and studied in half cell configurations by means of galvanostatic cycling, cyclic voltammetry and electrochemical impedance spectroscopy. It was observed that nanoparticles encapsulated with graphene demonstrated high specific capacity but limited cycle life. In contrast, nanoparticles with void and/or SiO2 were able to deliver improved cycle life. It is suggested that the existence of the void and/or residual SiO2 layer limits the formation of rich LiXSi alloys in the core silicon nanoparticle, providing higher mechanical stability during the lithiation and delithiation processes.

New Insights into the Reactivity of Detonation Nanodiamonds during the First Stages of Graphitization

The present study aims to compare the early stages of graphitization of the same DND source for two annealing atmospheres (primary vacuum, argon at atmospheric pressure) in an identical set-up. DND samples are finely characterized by a combination of complementary techniques (FTIR, Raman, XPS, HR-TEM) to highlight the induced modifications for temperature up to 1100 °C. The annealing atmosphere has a significant impact on the graphitization kinetics with a higher fraction of sp2-C formed under vacuum compared to argon for the same temperature. Whatever the annealing atmosphere, carbon hydrogen bonds are created at the DND surface during annealing according to FTIR. A “nano effect”, specific to the < 10 nm size of DND, exalts the extreme surface chemistry in XPS analysis. According to HR-TEM images, the graphitization is limited to the first outer shell even for DND annealed at 1100 °C under vacuum

The Effectiveness of Dental Protection and the Material Arrangement in Custom-Made Mouthguards

Experimental research studies have shown that wearing a mouthguard (MG) is an effective way to prevent tooth or maxillofacial trauma. However, there is a lack of scientific information regarding how the material arrangement within the mouthguard can modify its mechanical response during an impact. Hence, this study aimed to evaluate the influence of material arrangement within custom-made mouthguards on stress transmitted to anterior teeth, bone, and soft tissue after impact. Four 3D finite element models of a human maxilla were reconstructed based on the CBCT of a young patient and analyzed according to the presence or absence of a mouthguard and the type of material arrangement within those with a mouthguard: model NMG with no mouthguard; model CMG representing the conventional arrangement with a single 4 mm-thick ethylene-vinyl acetate (EVA) foil; model FMG presenting layer arrangement with two 1 mm-thick foils of EVA in the outer shell and one 2 mm-thick foil of EVA foam in the core; model HMG presenting a 1 mm-thick compact inner and outer shell of EVA and a 2 mm wide air-filled zone in the core. Linear quasi-static analysis and frontal load were used to simulate an impact with an energy of 4.4 J. Isotropic linear elastic properties were assumed for the bone and teeth but not for the mouthguard protection and oral soft tissues. The results were evaluated and compared in terms of displacement, stretches, and stresses. All the mouthguards analyzed reduced the risk of injury to teeth and bone, reducing the displacement and stress of these structures. However, the implementation of a honeycomb structured layer allowed more significant displacement and deformation of the mouthguard's external layer, thus promoting higher protection of the anatomic structures, namely the root dentin and the bone tissue. Nevertheless, the results also indicate that improving the mouthguard flexibility might increase the soft tissue injuries.

Research of Gfrp Shell Confined Concrete Columns Behavior Under Axial Compression

Постановка задачи. Исследуется влияние внешних композитных (стеклопластиковых) оболочек, которые имеют различные физико-механические свойства в продольном и поперечном направлениях, на увеличение прочности находящегося внутри оболочек бетонного ядра. Результаты. Представлены результаты экспериментальных исследований несущей способности, позволяющие оценить эффективность применения внешней цельной стеклопластиковой оболочки в качестве усиления бетонной стойки. Результаты исследования позволили определить основной фактор, значительно влияющий на несущую способность гибридной стойки с композитной оболочкой. Выводы. Получен более высокий показатель несущей способности гибридных стоек в сравнении с традиционно применяемыми в мостостроении стойками. Тем самым доказана возможность применения в опорах мостовых сооружений гибридных по материалу стоек, состоящих из внешней цельной стеклопластиковой оболочки и внутреннего бетонного ядра, которые ранее не применялись в мостовых конструкциях. Statement of the problem. The influence of external GFRP (glass-fiber-reinforced-plastic) shell, with different physicomechanical longitudinal and transverse properties on increasing the strength of the concrete core is investigated. Results. The article presents the results of experimental investigations of the load-bearing capacity to evaluate the effectiveness of using a solid fiberglass outer shell as a reinforcement of a concrete column. The results of the study has allowed us to establish the major factor that significantly affects the load-bearing capacity of a hybrid column with a composite shell. Conclusions. A higher load-bearing capacity of hybrid supports in comparison with the concrete columns traditionally used in bridge construction. This proves the possibility of using hybrid columns in the supports of bridge structures consisting of concrete core confined solid fiberglass outer shell that were not previously used in bridge structures.