Possible detection of failure wave velocity in SiC using hypervelocity penetration experiments

Review of experimental techniques for high rate deformation and shock studies

“…Gauges may be useful here in detecting loss of shear strength in the material in the transparent region between the shock wave and the failure front. Failure fronts have also been sought in other brittle materials [200,201], although the evidence for their existence in materials apart from silica glasses is still controversial. Some researchers Fig.…”

“…claim that in some brittle materials (such as alumina) failure does not propagate very far into the material from the impact surface [202][203][204], although others claim this may be a measurement artefact [205,206]. A few researchers have linked failure fronts to resistance to ballistic or hypervelocity impact [201,[207][208][209].…”

Re-examination of the evidence for a failure wave in SiC penetration experiments

“…Analysis of the penetration time data determined the penetration velocity vs. impact velocity (u-v p ) up to approximately v p ¼ 4.5 km/s. Analysis of data from copper shaped-charge experiments conducted by Kozhushko and Sinani [2,3] extended the u-v p data to v p $7 km/s. The u-v p data are plotted in Fig.…”

“…The pressure-assisted densification (PAD) SiC-B samples (r t ¼ 3.22 g/cm 3 ) were cylindrical in shape and confined laterally by a Ti sleeve and plastic sabot, and at the front and at the rear by an aluminum disk. The rods were made of pure tungsten (r p ¼ 19.3 g/cm 3 ). To prevent an influence of the lateral target dimensions, the ceramic diameter was 23.6 mm and the rod diameter (D) was 0.762 mm; i.e., the ratio of SiC diameter to rod diameter was 31.…”

“…This adjusted velocity normalizes for differences in material densities in the two sets of experiments. The increase in penetration resistance, inferred by the change in slope of the u adj -v p data at an impact velocity of approximately 4.5 km/s, was interpreted as possible evidence of a failure wave [4][5][6] in SiC [2,3]. The long-rod experiments were conducted in the reverse ballistic mode using a two-stage light-gas gun.…”