The Dynamic Response of Brittle Materials under Impact Loading

In order to make sense of the dynamic response of brittle materials under the certain range of impact strength, the numerical simulation for two kinds of representative ones glass and ceramic are conducted, in which the elastic micro-crack damage model is used. The plane impact experiments of ceramic and glass are summarized, which are used to compare with the simulation results. The simulation results show that the dynamic responses of brittle materials, failure wave and the plastic-like response appeared in glass and ceramic respectively are depended on their micro-cracks distribution in meso-scale. And moreover, both of failure wave and the plastic-like response are controlled by the same mechanism, and the different phenomena are just influenced by the size and distribution of the micro-cracks.

Multi-Thickness Target Plate Impact Experimental Approach to Failure Waves in Soda-lime Glass and Its Numerical Simulation

A multi-thickness target plate impact experimental technique is proposed in this paper and adopted in the research on the so-called failure wave phenomenon in soda-lime glasses, in which, four sub-targets in different thicknesses embedded in the target ring are impacted simultaneously and the longitudinal stress temporal curves at the backing surface of each of the sub-targets are measured by four manganin piezo-resistive stress sensors. Hence, the failure wave trajectory under a certain dynamic loading can be obtained by only one test, which can reduce considerably the experimental expense as well as the experimental period, and, more importantly, the measurement uncertainty resulted from different loading conditions in repetitious impact experiments is avoided. It is found that the propagating velocity of failure wave is approximate to a constant and increases with the magnitude of the impact loading, and there always exists an initial delay time for the initiation of failure wave behind the precursory shock wave, which decreases with the magnitude of impact loads. Moreover, a numerical simulation for the failure wave propagation is carried out by using the LS-DYNA applied software, together with a statistical isotropic elastic microcrack model to describe the dynamic damage evolvement of soda-lime glasses. It is demonstrated that both the critical damage value distributions and the free surface particle velocity temporal curves can be used to determine the failure wave trajectory, and the numerical results are consistent substantially with the experimental data.

Multi-Thickness Target Plate Impact Experimental Approach to Failure Waves in Soda-lime Glass and Its Numerical Simulation

A multi-thickness target plate impact experimental technique is proposed in this paper and adopted in the research on the so-called failure wave phenomenon in soda-lime glasses, in which, four sub-targets in different thicknesses embedded in the target ring are impacted simultaneously and the longitudinal stress temporal curves at the backing surface of each of the sub-targets are measured by four manganin piezo-resistive stress sensors. Hence, the failure wave trajectory under a certain dynamic loading can be obtained by only one test, which can reduce considerably the experimental expense as well as the experimental period, and, more importantly, the measurement uncertainty resulted from different loading conditions in repetitious impact experiments is avoided. It is found that the propagating velocity of failure wave is approximate to a constant and increases with the magnitude of the impact loading, and there always exists an initial delay time for the initiation of failure wave behind the precursory shock wave, which decreases with the magnitude of impact loads. Moreover, a numerical simulation for the failure wave propagation is carried out by using the LS-DYNA applied software, together with a statistical isotropic elastic microcrack model to describe the dynamic damage evolvement of soda-lime glasses. It is demonstrated that both the critical damage value distributions and the free surface particle velocity temporal curves can be used to determine the failure wave trajectory, and the numerical results are consistent substantially with the experimental data.

Fracture Model of the Failure Wave in the Shocked Brittle Materials

A new failure model was developed to describe the failure wave formation and propagation in shocked glass. The progressive percolation of microcracks into the stressed body gives rise to the failure wave phenomenon which could be regarded as a diffusion process. The propagation of failure front is governed by a nonlinear diffusion equation. The dynamic damage constitutive relation is built up to compute the stress state in the material through the failure process. Numerical results are presented and compared to lateral stress gauge measurements in shocked glasses. It is shown that the proposed model can capture the essence of the failure wave phenomenon.