Ice vs. steel: Ballistic impact of woven carbon/epoxy composites. Part I - Deformation and damage behaviour

With extensive use of composite materials in aerospace, marine, energy and defence applications, their susceptibility to impact events is still an unresolved problem. In this paper, impacts of carbon fibre/epoxy composite specimens with solid (steel) and fragmenting (ice) spherical projectiles are studied extensively, using a combination of non-invasive analysis techniques to assess their dynamic deformation behaviour and resultant damage. The velocity magnitudes of high-intensity impacts varied between 70 and 90 m/s for solid projectiles and between 300 and 500 m/s for fragmenting ones, resulting in three consistent and comparable levels of structural damage for both cases. A new in-depth deformation analysis method based on high-speed digital image correlation was utilised to assess the effect of both the projectile type and impact velocity, resulting in a deeper understanding of the specimen's deformation behaviour allowing detailed observation of its stages during the impact event. Additionally, both visual and non-invasive methods were employed to analyse the extent of damage related to various dynamic loading conditions. X-ray computed tomography was used to implement a full volumetric analysis of internal damage and resulted in a detailed insight into inter- and infra-ply damage modes.