Analysis of the high strain-rate behaviour of polyethylene based nanocomposites Chandragupt Gorwade 1 , Foz Hughes 3 , Dongyu Cai 2 , Ian Ashcroft 1 , Vadim Silberschmidt 1 , Gerry Swallowe 3 , Mo Song 2 , Steve Shaw 4 . 1 Wolfson School of Mechanical and Manufacturing Eng., Loughborough University, UK 2 Department of Materials, Loughborough University, UK 3 Department of Physics, Loughborough University, UK 4 DSTL, Porton Down, UK (TBC) Keywords Split Hopkinson pressure bar test, armour, nanocomposites, finite element analysis Abstract Advanced polymeric materials and polymer based nanocomposites are finding an increasing range of industrial and defence applications. These materials have the potential to improve combat survivability, whilst reducing cost and weight. This study deals with nanocomposites manufactured from blends of low density polyethylene (LDPE) with various nanofillers. The high strain rate behaviour of these materials was investigated using the split Hopkinson pressure bar (SHPB) test. The experimental results for non-reinforced materials were used as a reference to analyse the effect of the nanofillers on the properties and performance of the nanocomposites. These results, together with those obtained from other mechanical tests, will be used as input into finite-element analyses to simulate the performance of these materials in lightweight armour applications. In the first step, the finite element model was validated by simulating the SHPB test and comparing the predicted results with those from the experiments. Explicit finite element analysis was used for the simulation. The fully developed model was able to demonstrate the behaviour of the test bar and specimen interaction correctly and reasonably good agreement between predicted and experimental results was observed. 1. Introduction The need for efficient, lightweight armour has never been so great as it is today. Increasing numbers of personnel, both military and civilian are being placed in an expanding variety of life- threatening situations and we must recognise the responsibility to maximise their combat survivability. One way to help protect such people is to provide them with some form of armour. Typical body armour solutions consist of a bullet-proof layer, commonly made from materials such as Kevlar [5] for lightweight armour, or hardened steel or ceramic plates where a higher degree of protection is required. Additionally, a liner is necessary to reduce the risk of any blunt-force trauma behind the bullet-proof layer. An ideal liner would have the ability to elastically deform under the impact point, dissipating some of the energy, whilst maintaining a degree of rigidity, spreading the remainder of the impact force over a relatively wide area. In modern body armour systems, ultra- high molecular weight polyethylene (UHMWPE) is often used for the liner, however, it is heavy and expensive to produce. The aim of this project is to attempt to produce a new material for use in body armour linings which meets or exceeds the mechanical properties of UHMWPE, whilst providing a reduction in the overall weight and/or cost of production. Nanomaterials, such as carbon nanotubes (CNTs) and nanoclay offer exciting possibilities in the reinforcement of composites. In this work a range of LDPE based nanocomposites are tested at high strain rate as an initial part of their evaluation as usable armour materials. 2. Material For the initial experimental testing LDPE blend samples were used, with reinforcement of carbon nanotubes (CNT), clay and carbon black (CB). Applied Mechanics and Materials Vol. 70 (2011) pp 237-242 Online available since 2011/Aug/18 at www.scientific.net © (2011) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMM.70.237 All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 128.243.253.114-11/09/12,12:11:02)