Browsing by Author "Shepherd, C. J."

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    The dynamic behaviour of ballistic gelatin
    (AIP American Institute of Physics, 2009-12-31T00:00:00Z) Shepherd, C. J.; Appleby-Thomas, Gareth J.; Hazell, Paul J.; Allsop, Derek F.
    In order to characterise the effect of projectiles it is necessary to understand the mechanism of both penetration and resultant wounding in biological systems. Porcine gelatin is commonly used as a tissue simulant in ballistic tests because it elastically deforms in a similar manner to muscular tissue. Bullet impacts typically occur in the 350–850 m/s range; thus knowledge of the high strain-rate dynamic properties of both the projectile and target materials are desirable to simulate wounds. Unlike projectile materials, relatively little data exists on the dynamic response of flesh simulants. The Hugoniot for a 20 wt.% porcine gelatin, which exhibits a ballistic response similar to that of human tissues at room temperature, was determined using the plate-impact technique at impact velocities of 75–860 m/s. This resulted in impact stresses around three times higher than investigated elsewhere. In US−uP space the Hugoniot had the form US = 1.57+1.77 uP, while in P−uP space it was essentially hydrodynamic. In both cases this was in good agreement with the limited available data from the literature.
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    On the dynamic behavior of three readily available soft tissue simulants
    (American Institute of Physics (AIP), 2011-12-31) Appleby-Thomas, Gareth J.; Hazell, Paul J.; Wilgeroth, James Michael; Shepherd, C. J.; Wood, David C.; Roberts, A.
    Plate-impact experiments have been employed to investigate the dynamic response of three readily available tissue simulants for ballistic purposes: gelatin, ballistic soap (both subdermal tissue simulants), and lard (adipose layers). All three materials exhibited linear Hugoniot equations-of-state in the US-uP plane. While gelatin behaved hydrodynamically under shock, soap and lard appeared to strengthen under increased loading. Interestingly, the simulants under test appeared to strengthen in a material-independent manner on shock arrival (tentatively attributed to a rearrangement of the amorphous molecular chains under loading). However, material-specific behavior was apparent behind the shock. This behavior appeared to correlate with microstructural complexity, suggesting a steric hindrance effect.