Experimental and numerical investigation on dynamic fracture behavior of a ZrB2-SiC composite ceramic

The effect of the loading rate on the dynamic fracture behavior of a ZrB₂-SiC ceramic was investigated using a split Hopkinson pressure bar on a single-edge notch beam. The dynamic fracture toughness was measured, and the failure mode of the ZrB₂-SiC ceramic was identified. The rate-dependent constitutive model of JOHNSON_HOLMQUIST II (JH-II) was utilized to analyze the effect of the loading rate on the stress intensity factor and the failure process of the ZrB₂-SiC ceramic. Results show that the dynamic fracture toughness and the energy dissipation rate increase with the increase of the loading rate. The dynamic fracture toughness improved from 9.92 MPa⋅m\(^{1/2}\) at 6.68×104 MPa⋅s⁻¹ to 31.5 MPa⋅m\(^{1/2}\) at 28.26×104 MPa⋅s⁻¹. The JH-II model was found suitable to model the dynamic fracture behavior of the ZrB₂-SiC ceramic. Both experimental and numerical results showed that the fracture process of the ZrB₂-SiC ceramic showed dependence on the loading rate. The crack first initiated from the plane of the notch induced by the tensile stress applied near the crick tip. At high loading rates, the ZrB₂-SiC ceramic specimen absorbed more energy and fractured to a larger number of small fragments than at a lower rate.