Impact velocity effect on the delamination of woven carbon–epoxy plates subjected to low-velocity equienergetic impact loads

The low velocity impact behaviour of a woven carbon fibre/epoxy composite has been analysed in this work. The study has been divided in two experimental phases performed in a drop-weight machine. Firstly, an impact has been carried out to determine the main damage mechanisms appearing over the structure for impact energies between 1 and 20 J. Force time curve patterns and three different damage inspection techniques have been employed to define an incident impact energy range (between 1.75 and 8.8 J) where delamination is the main damage mode over the structure. Secondly, two impact energy levels within this range have been chosen to analyse the impact velocity effect on the generated delamination. Equienergetic impact loads, achieved with different mass and velocity combinations, have been carried out for this analysis. Results show how delaminated area can increase in a 45% while increasing impact velocity, and how this delamination growth, can lead to a 20% reduction of the residual stiffness of the structure within the analysed energy and velocity ranges.