Soil forces on deep tillage tools
Date
2002-04
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Masters
Abstract
The force performance of different tillage tools was investigated in sandy loam and
clay loam fields at a working depth of 18 cm and at three operating speeds. The tools
included four cutting edges: flat, 90°, 40°, and elliptical with rake angles of 20° and
33°. Draft, vertical, and side forces were measured using six loadcells in a three
directional arrangement such that two loadcells measured draft, three measured
vertical force, and one measured the side force. All the variables were combined to
form a 2x3x4 factorial experiment with three replicates. The force data were
analyzed using balanced analysis of variance with a Mini tab statistical package. The
instrumentation included an accelerometer to investigate the movement of the shank,
a potentiometer to determine working depth, and a magnetic pickup to indicate
operating speed. The draft measurements for all tools were compared to the values
generated using a prediction equation from an ASAE standard. Results indicated that
two of the modified tools had lower draft than the predicted values.
Draft increased from a minimum for the flat cutting edge to a maximum for the
elliptical shape in the sandy loam and clay loam soils. There was no significant
difference in draft with respect to the rake angle, but there was a significant increase
in draft due to higher operating speeds in sandy loam and clay loam soils. The clay loam field had draft values lower than those of the sandy loam field. Similar trend
was observed for the vertical force. Due to tool symmetry, the side force was
insignificant. A linear relationship existed between resultant force and operating
speed in both soil types.
The accelerometer data showed that there was vibration of the shank during tillage.
The results were similar to the ones reported by Zhang (1997) and indicated an
increase in vibration frequency of the shank with an increase in resultant force.
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Degree
Master of Science (M.Sc.)
Department
Agricultural and Bioresource Engineering
Program
Agricultural and Bioresource Engineering