Energy-based approach to impact damage in CFRP laminates

The purpose of this paper is to propose that, whereas a force-based approach works well for the onset of damage, an energy-based approach is more suitable for the determination of the extent of damage. An approach based on maximum load does not work in the cases investigated here because the loads level off once a certain displacement or energy (around 25 J) is reached. On the other hand, an energy-based approach is successfully employed to quantify the energy absorbed by different mechanisms during impact. A complete energy balance for impact of CFRP laminates includes three major energy terms: the energy stored elastically, the energy absorbed in creation of matrix damage and the energy absorbed in creation of fibre damage. There are also two smaller terms: the energy for permanent indentation and a system loss term. (C) 1997 Published by Elsevier Science Limited.