Browsing by Author "Roberson, Colin J."

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    The design of mosaic armour: the influence of tile size on ballistic performance
    (2008-03-15T00:00:00Z) Hazell, Paul J.; Roberson, Colin J.; Moutinho, Mauricio
    Silicon carbide square tiles of different areal geometries and manufactured via two different processing routes have been bonded to polycarbonate layers to evaluate their ballistic performance. Four ceramic tile sizes were tested: 85mm, 60 mm, 50 mm and 33 mm. In each case the residual depth-of-penetration into a polycarbonate semi-infinite backing was recorded. To elucidate the penetration and failure mechanisms, a computational model using the JH-1 ceramic model [Holmquist TJ, Johnson GR. Response of silicon carbide to high velocity impact. J Appl Phys 2002;91:5858–66] of the projectile used in the experimental study penetrating into a silicon carbide-faced polycarbonate was implemented in the hydrocode AUTODYN-2D. This paper shows that there is a critical dimension of tile that should be used in a silicon carbide-based ceramic-faced mosaic armour system design to ensure optimum system performance when each tile is struck centrally.
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    On the critical thickness of ceramic to shatter WC-Co bullet cores
    (2011-05-11) Hazell, Paul J.; Roberson, Colin J.
    In this paper, the 7.62 mm x 51 mm FFV round consisting of a tungsten carbide core (1550 HV) and copper gilding jacket was fired at silicon nitride, titanium diboride, tungsten carbide and silicon carbide ceramics. Of particular interest is the thickness of the ceramic required to change the penetration mechanism from that of an intact body to broken body, and finally, to becoming completely fragmented during penetration. There appears to be a correlation between the acoustic impedance of the ceramic and the thickness required to shatter the core. The effect of ceramic hardness is less-marked. The existence of a critical thickness to shatter the core suggests that it is not only the magnitude of the shock-stress imparted to the core but the duration of the shock-stress that is important in causing shattering of these relatively brittle cores.
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    Resistance of silicon carbide to penetration by a tungsten carbide cored projectile
    (2003-12-31T00:00:00Z) Roberson, Colin J.; Hazell, Paul J.
    Silicon carbide is well known as being a ceramic that can be employed as part of an effective armour solution to defeat small arms ammunition. Its relatively high hardness and ability to accommodate large plastic strains at high confining pressures lend itself to offering sufficient resistance to defeat tungsten carbide cored projectiles. In this paper, the 7.62 × 51mm FFV*† round consisting of a tungsten carbide core (Hv 1200) and copper gilding jacket was fired at a variety of thicknesses and types of silicon carbide. The results suggest that it is not only the type of silicon carbide that is important in the design of the armour solution but also a critical thickness that is necessary to sufficiently resist and damage the round. This paper will also draw conclusions on the effectiveness of the manufacturing routes of silicon carbide for armour solutions. This paper will be of interest to armour system designers and manufacture