SOME DYNAMIC CHARACTERISTICS OF ROCKS
NAVAL ORDNANCE TEST STATION CHINA LAKE CA
Pagination or Media Count:
A study was made of the transmission and decay of pulses produced both by impact and explosive loading in a rock classified as a diorite. The samples were chosen and prepared with sufficient care and tested under identical conditions so that reproducibility of results comparable to that expected in metallic systems was obtained. Ballistically suspended Hopkinson bars of diorite of 34-inch diameter and approximately 22 inches long were subjected to longitudinal impact by spherical and flat-ended cylindrical projectiles of hardened steel at an initial velocity of about 3,300 insec. Strain gages attached to the specimens at various stations permitted a re cording of the shape and velocity of propagation of the resultant wave. Similar experiments were performed on an aluminum alloy bar of identical size to assess the magnitude of the dispersion resulting from the three-dimensional character of the rod. The nature of the transformation of the pulse during passage permits as assessment of the validity of various models proposed for geologic substances in the field of seismology. A further detailed study of the internal response of the samples to such pulse passage was accomplished by means of microscopy and static tests, which correlated very well with the dynamic results.