SHOCK RESPONSE OF ROCK AT PRESSURES BELOW 30 KILOBARS

A SYSTEM HAS BEEN DEVELOPED FOR CONTINUOUS MEASUREMENTS OF BOTH SHOCK WAVE PROPAGATION VELOCITY AND SPECIMEN PARTICLE VELOCITIES RESULTING FROM THE PASSAGE OF A SHOCK WAVE PRODUCED BY A FLAT-PLATE IMPACT. A STRESS-STRAIN RELATION CAN BE DEDUCED FROM THE WAVE AND PARTICLE-MOTION DATA. THE SYSTEM HAS AN UPPER LIMIT OF APPROXIMATELY 30 KILOBARS. MOST HUGONIOT WORK HAS BEEN CONDUCTED AT PRESSURES ABOVE 30 KILOBARS, BUT THIS SYSTEM WILL MAKE IT POSSIBLE TO DETERMINE HUGONIOT DATA FOR LOWER PRESSURES. TO DETERMINE VELOCITIES, FINE WIRES ARE EMBEDDED IN THE TEST MATERIAL, AND THE SPECIMEN IS MOUNTED IN A MAGNETIC FIELD AT THE END OF A COMPRESSED-AIR GUN BARREL. ANY MOVEMENT OF A PORTION OF A WIRE WHICH CUTS THE MAGNETIC-FLUX LINES PRODUCES AN ELECTROMOTIVE FORCE PROPORTIONAL TO THE INSTANTANEOUS VELOCITY. STRESS WAVES CAUSING THE WIRE MOVEMENT ARE PRODUCED BY IMPACTING THE SPECIMEN WITH AN ALUMINUM PROJECTILE. THE VELOCITY OF PROPAGATION CAN BE DETERMINED FROM THE INITIAL RISES OF THE VOLTAGE SIGNALS FROM THE INDUCTION WIRES. THE FINAL STATE BEHIND THE STRESS WAVE IS DETERMINED BY THE APPLICATION OF THE CONSERVATION OF MASS AND MOMENTUM EQUATIONS. THESE EQUATIONS ARE BASED ON THE ASSUMPTION THAT AN EQUILIBRIUM STATE OF STRESS IS REACHED BEHIND THE SHOCK WAVE, AND ARE VALID ONLY IN THE REGION OF UNIAXIAL STRAIN. THE DATA OBTAINED FROM THESE EQUATIONS CORRESPOND TO THE HUGONIOT OR THE LOCUS OF SHOCKED-END STATES REACHED. PRELIMINARY STUDIES OF THE DYNAMIC PROPERTIES OF PLEXIGLAS AND FOUR ROCK TYPES AT LOW PRESSURES ARE REPORTED. PLEXIGLAS WAS USED AS A REFERENCE MATERIAL TO VERIFY THE TEST METHOD. GRANITE WAS TESTED AT A PRESSURE OF APPROXIMATELY 14 KILOBARS. THE OTHER MATERIALS WERE TESTED AT PRESSURES LESS THAN 5 KILOBARS. THE SHOCK RESPONSE DURING LOADING OBSERVED FOR BASALT, GRANITE, AND QUARTZITE IS ESSENTIALLY LINEAR. STRESS-STRAIN DATA ON PLEXIGLAS, GRANITE AND QUARTZITE WERE FOUND TO AGREE VERY FAVORABLY WITH EXTRAPOLATED DATA FOR HIGHER PRESSURE LEVELS. /AUTHOR/

  • Supplemental Notes:
    • No 6-802- pP 1-41, 10 FIG, 13 REF
  • Authors:
    • Ainsworth, D L
    • Sullivan, B R
  • Publication Date: 1967-11

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  • Accession Number: 00235305
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Aug 12 1994 12:00AM