STUDIES OF AERIAL CONE PENTEROMETER IMPACT VELOCITY-IMPACT FORCE INVESTIGATIONS, 1968
TWENTY-SEVEN TESTS WERE CONDUCTED TO DETERMINE THE IMPACT VELOCITY OF AN AERIAL CONE PENETROMETER DROPPED FROM HEIGHTS OF 50, 100, 150, 200, AND 241 FT. FROM A 250-FT-HIGH PARATROOP TRAINING TOWER AND FROM HEIGHTS OF 280 AND 560 FT FROM A 2000-FT-HIGH TV TRANSMITTING TOWER. MOVIES OF THE PENETROMETER DURING THE PORTION OF THE FLIGHT JUST PRIOR TO IMPACT WITH THE GROUND SURFACE WERE MADE WITH A HIGH-SPEED MOTION PICTURE CAMERA. THE VELOCITY OF THE PENETROMETER WAS DETERMINED BY VIEWING THE MOVE FILM WITH A MOTION ANALYZER. A HYPERBOLIC CURVE DEFINES THE IMPACT VELOCITY-HEIGHT RELATION OF THE AERIAL CONE PENETROMETER USED IN THIS STUDY OVER THE RANGE OF HEIGHTS OF DROPS LISTED AABOVE. A STATISTICAL EQUATION FOR THE CURVE WAS DEVELOPED FROM A RELATION ESTABLISHED BETWEEN HEIGHTS AND VELOCITY. THE EQUATION PERMITS THE COMPUTATION OF THE IMPACT VELOCITY OF THE PENETROMETER IN TERMS OF HEIGHT OF DROP. STATISTICAL TECHNIQUES WERE USED TO EVALUATE THE RELIABILITY OF THE EQUATION. IT WAS CONCLUDED FROM THE ANALYSIS THAT THE EQUATION CAN BE USES WITH A HIGH DEGREE OF CONFIDENCE AND VELOCITY DETERMINATIONS CAN BE EXTRAPOLATED TO A HEIGHT OF 1000 FT (440 FT GREATER THAN THE MAXIMUM MEASURED HEIGHT). THE ANGLE FORMED BETWEEN THE TAIL VANES ON THE PENETROMETER BARREL DURING FLIGHT AFFECTS THE IMPACT VELOCITY INVERSELY; AS VANE ANGLE INCREASES VELOCITY DECREASES. A VARIATION OF TAIL VANE ANGLE OF 43 DEG PRODUCES A VARIATION IN IMPACT VELOCITY OF APPROXIMATELY 5.0 FPS WITH A RESULTING VARIATION IN IMPACT FORCE OF 5 LB. THIS VARIATION IN VELOCITY AND IMPACT FORCE WOULD PRODUCE LITTLE IF ANY EFFEFT ON SPRING DEFLECTION AND WOULD HAVE NO EFFECT ON THE ABILITY OF THE FIRING MECHANISM OF THE PENETROMETER TO INDICATE THE PRESELECTED SOIL STRENGTH UPON IMPACT OF THE PENETROMETER WITH THE GROUND SURFACE. IT IS RECOMMENDED THAT 600 FT BE ESTABLISHED AS THE MINIMUM HEIGHT FROM WHICH THE AERIAL CONE PENETROMETER BE DROPPED. FOR A MINIMUM HEIGHT OF DROP OF 600 FT, SPRING DEFLECTION-CONE INDEX RELATIONS PRESENTED HEREIN CAN BE USED TO DETERMINE THE PROPER DISTANCE FROM THE CARTRIDGE AT WHICH THE FIRING PIN SHOULD BE SET TO INDICATE A PRESELECTED SOIL STRENGTH. PREVIOUSLY DETERMINED THEORETICAL IMPACT FORCES WERE VERIFIED. /AUTHOR/
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Supplemental Notes:
- No 3-462, REPT 4, 32 PP, 8 FIG 2 TAB, 11 REF
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Authors:
- Kennedy, J G
- Publication Date: 0
Media Info
Subject/Index Terms
- TRT Terms: Crash tests; Impacts; Motion pictures; Penetrometers; Statistical analysis; Velocity
- Subject Areas: Data and Information Technology; Geotechnology; Highways; Research;
Filing Info
- Accession Number: 00229888
- Record Type: Publication
- Files: TRIS
- Created Date: Nov 3 1970 12:00AM