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Title: Studies of Aerial Cone Penetrometer. Report 4, Impact Velocity-Impact Force Investigations, 1968
Authors: Kennedy, James G.
Mobility and Environmental Systems Laboratory (U.S.)
Keywords: Penetrometers
Publisher: U.S. Army Engineer Waterways Experiment Station
Series/Report no.: Technical Report (U.S. Army Engineer Waterways Experiment Station);no. 3-462 rept.4
Abstract: An aerial cone penetrometer was dropped from heights of 50, 100, 150, 200, 241, 280, and 560 ft to determine its velocity at impact with the ground surface. A high-speed motion picture camera recorded t.he flight of the penet.rometer just prior to impact. Velocity was determined by viewing the movie film with a motion analyzer. A hyperbolic curve defines the impact velocity-height relation of the penetrometer used in this study throughout the range of drop heights listed above. A statistical equation for the curve was developed from a relation established between height and velocity. The equation permits computation of impact velocity in terms of height of drop. Statistical techniques were used to evaluate the reliability of t.he equation. It was concluded from the analysis that the equation 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 barrel during flight affects the impact velocity inversely; as vane angle increases velocity decreases. A variation of vane angle of 43 deg produces a variation in impact velocity of approximately 5.0 fps and in impact force of 5 lb. This variation would produce little if any effect on spring deflection and no effect on the ability of the firing mechanism of the penetrometer to indicate the preselected soil strength upon impact. It is recommended that 600 ft be established as the minimum height from which the penetrometer be dropped. Previously determined theoretical impact forces were verified.
Description: Technical Report
Gov't Doc #: Technical Report No. 3-462 Report 3
Rights: Approved for public release; distribution is unlimited
Appears in Collections:Technical Report

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