Influence of a Steel Strike Face on the ballistic resistance of an Ultra High Molecular Weight Polyethylene fibre reinforced thermoplastic matrix composite considering energy absorption and penetration

Jason Harvey

Abstract


A series of experimental target panels were constructed from ultra-high molecular weight polyethylene fibre reinforced thermoplastic using a locally developed compression moulding procedure. Half of the experimental test panels were bonded to a 1.2mm steel strike face with an acrylic adhesive forming fibre metal laminates for ballistic testing. The panels were subjected to ballistic impact loading from 55 grain jacketed soft point spitzer projectiles, fired from a rifle at velocities above 103 ms-1 under open environmental conditions. Velocity measurements were taken fore and aft with Caldwell precision chronographs, and energies calculated and normalised with areal density. Plotting of velocity, energy, thickness and areal density suggested the addition of a steel strikeface reduced the energy absorption capacity of the thermoplastic matrix laminate by approximately 50%. This result was found to be inconclusive when reviewed against high-speed video imagery. Optical microscopy was conducted on the sectioned, impacted laminates where wide area delamination was observed to initiate up to 35% earlier through thickness in fibre metal laminates. This result complimented surface profilometry observations where a 35% increase in back face deformation area was identified for fibre metal laminates. The fibre metal laminates were observed to initiate significant delamination from a thickness of 47%, with back face deflection extending to 28mm. These results illustrated a complimentary correlation with analytical calculations made using equations from previous works. Identifying this result and noting that wide area delamination is the characteristic ballistic resistance mechanisms of armour laminates, it is suggested an increase in ballistic resistance of up to 35% may be achieved by the addition of a steel strike face. To further increase the scope of results a commercial laminate was included in the testing regime qualifying the response of the panels to be consistent with commercial ballistic laminates.

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