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Dynamic compression tests at varying strain rate in rock

Conference · · EOS, Trans., Am. Geophys. Union; (United States)
OSTI ID:5369957

Dynamic compression studies using high velocity impact facilities are usually considered to involve a catastrophic process of indeterminate loading rate by which a material is brought to a shock compressed state. Although frequently the case, methods are also available to control the rate of strain during the shock compression process. One of the most accurate methods of achieving this end makes use of the anomalous nonlinear elastic property of glass to transform an initial shock or step wave input into a ramp wave of known amplitude and duration. Fused silica is the most carefully calibrated material for this purpose and, when placed between the test specimen and the impact projectile, can provide loading strain rates to within a few percent in the range of 10/sup 4//s to 10/sup 6//s for stress states of 3.0 GPa or less. Ramp wave compression experiments have been conducted on dolomite down to strain rates of 3 x 10/sup 4//s. Both yielding and subsequent deformation at this strain rate agrees well with previous shock wave studies (epsilon approximately equal to 10/sup 6//s) and differs substantially from quasistatic measurements (epsilon approximately equal to 10/sup -4//s). The ramp wave studies have also uncovered a pressure induced phase transition in dolomite initiating at 4.0 GPa which has not previously been identified in shock wave or static experiments.

Research Organization:
Sandia Labs., Albuquerque, NM
OSTI ID:
5369957
Journal Information:
EOS, Trans., Am. Geophys. Union; (United States), Journal Name: EOS, Trans., Am. Geophys. Union; (United States) Vol. 57:12; ISSN EOSTA
Country of Publication:
United States
Language:
English