Rapid geometric characterization of ceramics fragments through split Hopkinson pressure bar tests

Abstract

The research on fracture mechanisms of brittle materials is extremely difficult such as the determination of the energy absorption modes and the geometric characteristics of debris. In this paper, a dynamic experimental fragment recovery device was developed to study the facture characteristics of A99 ceramics (the mass of Al2O3 accounts for 99%) based on the Split-Hopkinson pressure bar (SHPB) experiments, in which the energy absorption mechanism was revealed. A three-view characterization method was developed to obtain the geometric characterization formula under various strain rate; therefore, the geometric parameters of the fragments can be quickly characterized. The failure mode was investigated in correlation between strain rate and micro-cracks. It was found that the shape of the strain rate controlled the proportion of dissipated energy. At a lower strain rate the fragment was prone to needle shape, while at a higher strain rate (above 2001 s−1) the proportion of dissipated energy increased to 72% and the fragment shape tended to be nearly spherical. A formula based on strain rate was proposed to characterize the geometric parameters of the fragments without the need of geometry dimensions; therefore, the fragment rate can be quickly obtained, which could provide guidance for the design of ceramics parts.