The efficiency of ultra-high molecular weight polyethylene composite against fragment impact

This paper presents an experimental investigation into the ballistic resistance of ultra-high molecular weight polyethylene (UHMW-PE) composite, and compares its performance against a range of common metallic and composite armour materials. An extensive experimental program was conducted to determine the ballistic limit velocity (V<inf>50</inf>) of UHMW-PE composite against 12.7 and 20 mm fragment simulating projectiles (FSPs) for a wide range of thicknesses. For protection against these projectiles, UHMW-PE composite was found to be consistently more mass efficient than rolled homogeneous armour steel (RHA), high hardness armour steel (HHA), aluminium alloy 5059-H131, and polymer composites reinforced with aramid, glass or carbon fibres. In terms of armour space claim, UHMW-PE composite was found to be less efficient than both steel types and glass fibre-reinforced plastic, though it was comparable to aramid fibre-reinforced plastic, and was more efficient than aluminium 5059-H131 and carbon fibre-reinforced plastic. Scaling effects were observed that showed metals were more effective against smaller projectiles in terms of armour mass required to stop a given projectile kinetic energy. These effects were not observed to the same extent for UHMW-PE composite, giving rise to a higher UHMW-PE mass efficiency against larger projectiles

The effect of target thickness on the ballistic performance of ultra high molecular weight polyethylene composite

The ballistic performance of thick ultra-high molecular weight polyethylene (UHMW-PE) composite was experimentally determined for panel thicknesses ranging from 9 mm to 100 mm against 12.7 mm and 20 mm calibre fragment simulating projectiles (FSPs). Thin panels (similar to <10 mm thick) were observed to undergo large deflection and bulging, failing predominantly in fibre tension. With increased thickness the panels demonstrated a two-stage penetration process: shear plugging during the initial penetration followed by the formation of a transition plane and bulging of a separated rear panel. The transition plane between the two penetration stages was found to vary with impact velocity and target thickness. These variables are inter-related in ballistic limit testing as thicker targets are tested at higher velocities. An analytical model was developed to describe the two-stages of perforation, based on energy and momentum conservation. The shear plugging stage is characterised in terms of work required to produce a shear plug in the target material, while the bulging and membrane tension phase is based on momentum and classical yarn theory. The model was found to provide very good agreement with the experimental results for thick targets that displayed the two-stage penetration process. For thin targets, which did not show the initial shear plugging phase, analytical models for membranes were demonstrated as suitable

Matrix elements of the electromagnetic operator between kaon and pion states

We compute the matrix elements of the electromagnetic (EM) operator between kaon and pion states, using lattice QCD with maximally twisted-mass fermions and two flavors of dynamical quarks (Nf = 2). The EM operator is renormalized non-perturbatively in the RI'/MOM scheme and our simulations cover pion masses as light as 260 MeV and three values of the lattice spacing, ranging from ~ 0.07 up to ~ 0.1 fm. At the physical point our preliminary result for the K -> pion tensor form factor at zero-momentum transfer is fT[K\pi](0) = 0.42(2_stat), which differs significantly from the old quenched result fT[K\pi](0) = 0.78(6) obtained by the SPQcdR Collaboration with pion masses above 500 MeV. We investigate the source of this difference and conclude that it is mainly related to the chiral extrapolation of the quenched data. For the case of the tensor charge of the pion we obtain the preliminary value fT[\pi\pi](0) = 0.200(14_stat), which can be compared with the result fT[\pi\pi](0) = 0.216(34) obtained at Nf = 2 by the QCDSF Collaboration using higher pion masses.Comment: 7 pages, 5 figures, contribution to the XXVIII International Symposium on Lattice Field Theory, Lattice2010, June 14-19, 2010, Villasimius, Ital

A penetration model for semi-infinite composite targets

A penetration model for composites reinforced with high tenacity fibres like ultra-high molecular weight polyethylene (UHMW-PE) is proposed based on the modified Bernoulli theory typically used for metallic targets. The model describes penetration by tensile failure of the composite material through compression loading in an infinitely thick target and includes consideration for projectile deformation. The predicted projectile velocity and axial interface loads shows good agreement with numerical simulations for a deforming and rigid projectile condition against two grades of UHMW-PE composite. The model can also be used to predict transient projectile velocity and interface loads during the first phase of penetration (which acts over most of the penetration event) for a target of finite thickness. It was shown that transition to bulging occurs upon the arrival of the rarefaction wave, generated from the back of an unsupported target, at the projectile-target interface. The stress relief can lead to a change in penetration mode when the magnitude of release is sufficient to reduce the load at the interface below that of the target strength. This change in mode occurs late in the penetration event, and the model developed in this work is demonstrated to be valid up to this point

Improved analysis of the scalar and vector form factors of kaon semileptonic decays with Nf = 2 twisted-mass fermions

We investigate the vector and scalar form factors relevant for Kl3 semileptonic decays using maximally twisted-mass fermions with two flavors of dynamical quarks (Nf = 2). The simulations cover pion masses as light as 260 MeV and four values of the lattice spacing, ranging from ~0.05 up to ~0.1 fm, which allow to compute directly, for the first time, the continuum limit for the vector form factor at zero-momentum transfer, f_+(0). The preliminary result is f_+(0) = 0.9544(68), where the error is statistical only. We also extrapolate both form factors to the physical point and study their momentum dependence. Our results are in good agreement with those obtained from a dispersion analyses of the experimental data. Together with the form factors, we analyze the ratio of the leptonic decay constants f_K / f_pi, by imposing the constraint coming from the Callan-Treiman theorem, obtaining at the physical point f_K / f_pi = 1.190(8). Combining our results for f_+(0) and f_K / f_pi with the experimental measurements of the leptonic and semilpetonic decay rates, and using the determination of |V_ud| from nuclear beta decays, we determine the values of the Cabibbo angle |V_us| from both Kl3 and Kl2 decays, obtaining |V_us|^{Kl3} = 0.2266(17) and $|V_us|^{Kl2} = 0.2258(16)

Promoting smartness among local areas in a Southern Italian region: The Smart Basilicata Project

Making cities smarter and more competitive is one of the major challenges of climate change and energy security. Smart city initiatives have arisen Europe-wide to help cities to start planning their future in a new way to become more sustainable and resilient. New business models need to be investigated to foster local business development, innovative local administrations and industries, valorize the cultural heritage and the research outcomes and promote community’s participation. This transition is even more complex and necessary for sparsely populated regions with poor infrastructures in the buildings, manufacturing and transport domains and with a multi-layer local governance (e.g. Italian Towns, Provinces and Region). In this case, a widespread concept of smart city can be applied proposing systematic strategies for urban innovation with a regional-wide perspective. This paper focuses on a coordinated project aimed to promote smartness among local areas in a small region in Southern Italy (Basilicata). The ‘Smart Basilicata’ project constitutes a unique example in which, by working together, multi-layer public authorities, private enterprises, research organizations and universities drafted the basis for a regional strategy for smart-related issues