Dynamic deformation, damage and failure of carbon fibre composites under ballistic and blast loading

Carbon Fibre Reinforced Polymers (CFRPs) have proven to be a popular choice in many applications given their higher desired and advantageous high strength to weight ratio, which makes them ideal for extreme loading conditions such as; low velocity impacts through airborne debris (1-100 m/s), high velocity impacts with fragmenting hailstone clouds, or even close-proximity air blast shock waves. In a real environment, these dynamic loading conditions are very rarely mutually exclusive, and so it is necessary to analyse the combined loading of both an impact and air blast shockwave which then creates the following question. Which is the most destructive, an impact closely followed by an air blast or visa-versa?

With this in mind, the presented research is first focused on the experiment testing of a consistent CFRP specimen material to ballistic rigid steel and fragmenting ice projectiles, as well as air blast shock wave loading with in-situ deformation analysis via digital image correlation from high speed photography alongside the post loading damage analysis via x-ray tomography. The second part of the research then focuses on the development of a meso-scale modelling strategy for carbon fibre reinforce polymer (CFRP) via a phenomenological continuum damage approach, which delivers accurate through-thickness stress responses, strain-rate sensitive behaviour, and full damage-initiation and evolution tracking of various damage modes with stiffness degradation. The modelling approach was incorporated into Abaqus Explicit 6.14-4 as a user defined subroutine (VUMAT), with inter-ply delamination modelled via cohesive zone surfaces (CZSs).

Following a new approach to obtaining and extrapolating material parameters for CFRPs utilising a comparative literature search to obtain an array of common ratios, the CFRP model was validated against the ballistic and air blast experiments, the results of which demonstrate the model delivering accurate correlation of both the specimens deformation behaviour and observed resultant damage to the various experimental loading conditions without modification of the modelling parameters. Finally, the modelling approach was then employed to predict and analyse the hypothetical scenarios of the impact closely followed by an air blast and visa-versa, subjecting the CFRP to set combined loading conditions within the limits of those set out within the scope of the experiment studies.