A COMPARISON OF THE THROUGH THICKNESS STRAIN RATE SENSITIVITY OF EGLASS/EPOXY AND EGLASS/LPET UD COMPOSITES

摘要

Affordable fibre reinforced lightweight polymer materials are potential candidates to substitute rolled homogenous armour steel in add-on panels for military vehicles [1]. Among other threats, the panels protect against improvised explosive devices (IED), which produce explosions causing high strain rate deformation in both in-plane and out-of-plane directions of the plate as well as shearing. One of the major design decisions is the choice between a thermoset and thermoplastic matrix type where thermoplastic matrix systems are deemed to be favourable due to their higher inherent toughness [2]. The rate sensitivity of the out-of-plane properties for UD fibre laminates has been reported in the literature, but mostly for composite materials with a thermoset (e.g. epoxy) matrix [3-5]. The out-of-plane properties are dominated by the matrix behaviour [2] and an increase in stiffness and fracture stresses were found with increasing strain rate [3-5]. Since the matrix is dominant in the out-of-plane directions, the properties of the fibres have less influence on the rate effects. Thus it is interesting to compare how the strain rate affects the material properties between the two types of matrix materials when fibres are added. This is important with respect to assessing the materials ability to survive an impact and its resilience to multiple hits.