Exploration of energy absorption and viscoelastic behavior of CFRPs subjected to low velocity impact

The attention of the present work is focused on the energy absorption and transformation of carbon fiber reinforced polymer (CFRP) composites under low velocity impact. Moreover, the viscoelastic behavior of composites was explored by observing the changes of dent depths via a micrometer and 3D microscope. In addition, the residual strengths of CFRP specimens were investigated by the compression after impact (CAI) test. The results show that more than 88% of impact energy was absorbed by the CFRPs through reversible deformation, irreversible damage and viscoelastic behavior. The impact damage threshold value and the maximum allowable deformation of the CFRP laminates were 9 J and about half of its thickness respectively. The energy is mainly absorbed by deformation when the impact energy was not larger than the threshold value. The energy dissipated by viscoelastic behavior increased with the increase in the impact energy and even exceeded 1.4 J in the case of 21 J, which was much higher than the kinetic energy when the impact energy exceeded the threshold value. The residual strength of the CFRP laminates was related to the energy absorbed by irreversible damage.