S-wave tracing technique to investigate the damage and failure behavior of brittle materials subjected to shock loading

To reveal the intrinsic rules of dynamic damage and failure behavior for brittle materials subjected to shock loading, a so-called transversal shear wave tracing technique (SWT) is proposed and discussed in detail in the present paper based on the wave propagation theory and the combined compression–shear impact technique. The idea of the SWT method is to diagnose the material state at real time by measuring the propagation features of loading and unloading shear waves. By using SWT technique, the preliminary experimental results of fiber-reinforced cement (FCEM) with electromagnetic particle velocity gauges embedded in the sample at different locations are reported and analyzed. By tracing the shear wave propagation, it is found that the amplitude and speed of unloading shear wave (S−) are related to the damage degree of the material. Particularly, S− vanishes when impact velocities exceed 197 m/s, which discloses clearly a transition point from damage state to failure state of FCEM. It is significant for there is no obvious cusp to indicate such transition on the Hugoniot of FCEM. Some further studies are needed for understanding and developing of SWT method.