An hysteresis energy-based synthesis of fully reversed axial fatigue behaviour of different polypropylene composites

In this paper the hysteresis energy density per cycle was considered as fatigue damage index to rationalise in a single scatter band the fatigue behaviour of short glass fibre reinforced polypropylene (30 wt% 1-mm-long glass fibre), long glass fibre reinforced polypropylene (30 wt% 10-mm-long glass fibre) and 42 wt% calcium carbonate filled polypropylene. Moreover the nature of such a mechanical energy was investigated to establish to which extent dissipation is due to creep strains and it was found that hysteresis energy dissipated in a unit volume of material per cycle due to visco-elasticity is negligible with respect to the total hysteresis energy.