Dynamic damage in woven carbon/epoxy composites due to air blast

In this study, the dynamic response to air blast observed in a flat plate specimen of 2 x 2 twill weave T300 carbon fibre/epoxy composite is examined, using a combination of non-invasive analysis techniques. The study investigates deformation and damage following air blasts with incident pressures of 0.4 MPa, 0.6 MPa and 0.8 MPa, with wave speeds of between 650 m/s and 950 m/s. Digital image correlation was employed to obtain displacement data from the rear surfaces of the specimens during each experiment, then used to assess the effect of air blast magnitude on the specimen's response. 3D x-ray tomography was employed to assess the resultant internal damage within the samples, allowing for a damage cloud to be visualized for each specimen. It was demonstrated that the global deformation and transitions in curvature of each specimen appeared to be very similar for all damage cases and that only the out-of-plane displacement increased showing that the pressure magnitude had no effect on the curvature or modes during deformation. Damage was found to propagate from the rear surface of the specimens towards the front surface as the air blast magnitude increased. A finite-element model based on a phenomenological continuum damage approach was also developed and validated against the experimental data.