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

Long H Nguyen,Shannon Ryan,Stephen J Cimpoeru,Adrian P Mouritz,Adrian C Orifici

doi:10.1016/j.ijimpeng.2014.07.008

Abstract

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 (∼<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.

Highlights

Polymer-based fibre-reinforced composites such as ultra-high molecular weight polyethylene (UHMWPE) composite have been shown to be extremely effective against small calibre ballistic threats, in weight-critical applications [1] or as contact spall liners [2]
Iremonger [8] and Greenhalgh et al [9] found that thicker laminates show penetration under two distinct stages: an initial penetration stage characterised by shear failure of the fibres, and a second stage where partial penetration by the impactor causes a sub-laminate to bulge or break away and undergo deflection and bending
An extensive experimental program was conducted to understand the ballistic performance of ultra-high molecular weight polyethylene (UHMW-PE) composite panels

Summary

Introduction

Polymer-based fibre-reinforced composites such as ultra-high molecular weight polyethylene (UHMWPE) composite have been shown to be extremely effective against small calibre ballistic threats, in weight-critical applications (e.g. personal protection vests and helmets) [1] or as contact spall liners [2]. It is considered that these materials, when applied in thicker sections, may be suitable as a primary armour component for protection against higher lethality fragmentation threats. It has been found that the protection efficiency of some composites increases with thickness [3], which is driven by different penetration mechanisms occurring for thicker sections. The ballistic performance of thin UHMW-PE composite is well known [4][5], there have only been limited published experimental results for thick targets. The second stage is similar to the failure mode seen for thin laminates [10] or fabrics [11], with fibre failure in tension the dominant mechanism close to the ballistic limit

Methods

Results

Conclusion