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A Portable Constant‐rate Cone Penetrometer
Author(s) -
Lowery Birl
Publication year - 1986
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1986.03615995005000020031x
Subject(s) - penetrometer , penetration (warfare) , strain gauge , electrical engineering , materials science , acoustics , simulation , physics , environmental science , mathematics , computer science , engineering , soil science , operations research , soil water
A portable, constant‐rate, recording cone penetrometer was designed and field tested to eliminate operator‐associated variability with hand‐pushed penentrometers and to overcome the limited portability of tractor‐mounted penetrometers. An average penetration rate of 8.3 mm s −1 was achieved with a small high‐torque DC motor connected to a rack‐pinion gear system. The motor and gear system was mounted on a tripod that allowed the unit to be leveled and provided for a maximum penetration depth of 0.61 m. Force of penetration, as a function of depth, was determined with four strain gages mounted on a proving ring and a rotary encoder. The encoder provided a remote signal to drive a x‐y plotter providing 0.61 mm of chart per millimeter of soil penetrated. The coefficient of variation for the rate of penetration was 3.4%. The rate of penetration remained approximately constant when tested over a range of soil densities from 0.9 to 1.9 Mg m −3 .