Effect of temperature on low velocity impact damage and post-impact flexural strength of CFRP assessed using ultrasonic c-scan and micro-focus computed tomography

The effect of temperature on the low velocity impact resistance properties and on the post-impact flexural performance of CFRP laminates were studied. With this aim, 150 75 mm cross-ply carbon fibre/ epoxy laminates with a [0/90/90/0]2s layup, therefore with a total of sixteen layers, were impacted at ambient temperature (30 C) and at elevated temperatures (55, 75 and 90 C) at a velocity of 2 m/s using a drop weight impact tower. This was followed by flexural tests carried out at ambient temperature using a three-point bending rig. Damage assessment of impact and post-impact behaviour were carried out using ultrasonic C-scan and microfocus X-ray computed tomography (lCT). Interrupted flexural tests using lCT allowed delamination propagation to be observed. In general, lower projected damage was observed at elevated temperatures, which resulted also in a possible hindrance to delamination and shear cracks propagation during impact and in a greater amount of retained flexural strength after impact.