Material BehaviourRepeated low energy impact behaviour of self-reinforced polypropylene composites

The repeated impact behaviour of self-reinforced polypropylene composite has been characterised by tensile impact and instrumented falling weight tests. The nature of the tapes is highly anisotropic with strain hardening failure. Plastic deformation of the tape is the dominant mechanism, and the resulting penetration mode is a highly localised “star”-shaped hole. Damage and perforation thresholds are 5 J and 31.4 J respectively. Impact fatigue life exceeds 500 impact events up to 13 J, but drops sharply for 14 J. Strain-hardening is the origin of the trend of peak load increase and plastic deformation decrease with impact events. As a consequence, the amount of energy absorbed by each impact is reduced. However, when tape breaking takes place the absorbed energy increases up to perforation.