Doctoral Dissertations

Hassan Vazin

Date of Award

3-1982

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Biosystems Engineering

Major Professor

Bobby L. Bledsoe

Abstract

Vibratory tillage tools require less draft force than nonvibratory ones. However, because the total power requirement Is equal to or greater than that required for conventional tillage tools, vibratory plows have not been developed for popular use. The factors that govern performance of a vibratory plow are: frequency and ampli-tude of vibration, forward speed, direction of vibration, and angle and shape of the plow blade. Hundreds of tests are needed In different soils to determine what combination of these factors. If any, would result In the most efficient vibratory plow. Expense and time are limiting fac-tors In carrying out such extensive experimental work. For this reason, a means for simulating field performance would be of substantial help. This study Is an attempt to devise and evaluate a finite element model for determination of soil compaction caused by vibratory tillage. Soil Is assumed to be a linearly elastic, Isotropic, homogeneous, and layered medium. A finite element mesh was selected to represent the soil. To Idealize the action of a vibratory plow In soil, a sinusoidal forcing function was applied to the mesh. Compaction of the selected area of the mesh under the action of the forcing function then was taken as a means of representing compaction of the soil under the action of a vibratory plow. This analysis was performed for vertical and horizontal directions of the forcing function. Idealizing vertical and horizontal directions of vibration of the plow. To verify results obtained from the model, a vibratory plow with the capability of vibrating In either a horizontal or vertical direction, along with the capacity of providing a frequency range of 0-50 Hz and an amplitude range of 0-25 mm, was designed and constructed. The plow was tested in a field with soil having the same parameters used in the model analysis. Degree of soil compaction was the same for theoretical and experi-mental results. Also, the operating amplitude and frequency of vibration for the plow which gave the greater soil compaction closely agreed with amplitude and frequency which required the most total plow energy expen-diture as determined by Tompkins (1974) using the same soil type. The agreement of results gives hope that the finite element model has merit in determining operating parameters giving the most efficient plow energy utilization. General conclusions drawn from both theoretical and experimental work are: 1. Compaction of soil is a function of amplitude of vibration, increasing as amplitude increases within the range of 3 to 8 mm. 2. Compaction of soil is also a function of frequency of vibration. 3. Vertical direction of vibration shows a relative advantage over horizontal direction of vibration (produces less compaction).

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