| Author | Thangavadivelu, Surendranath |
| Call Number | AIT Thesis no. AE-86-14 |
| Subject(s) | Tillage--Research
|
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Abstract | Experiments were conducted to determine the nature of stress
field and the two dimensional deformation pattern generated in front of
model tillage tools . Four tools of aspect ratios 1. 5:1, 2.0:1, 2.5:1 and
3.0:1 were experimented in a soil bin, filled with Bangkok clay whose
moisture content was varied from 6 .9 to 28 . 0 per cent.
The pressure in the zone of influence of tillage tools was sensed
by rubber diaphragms, fitted on the sensing end of the pressure
transducers fabricated, based on the principle of inclined manometer.
The variation of the dynamic pressure caused by the tool movement was
recorded by photographing the fluctuating water level in the limbs of the
transducer. The two dimensional deformation patterns generated by the
moving tool were also recorded on photographic slides for different positions of the tool .
The data from the transducers was converted in terms of
stress. The three dimensional stress field produced in front of the tillage
tool at varying depth was plotted as a function of the distances along
three co-ordinate axis. A general three dimensional equation in second
degree was found to fit the data with R2 ranging from 0.924 to 0.983.
The equation fitted was found to be that of a quadric surface representing hyperboloid, ellipsoid or a paraboloid depending upon the value
of the co-efficient .
The stress field generated was found to be a regular surface
of revolution unlike the one predicted by the existing theory where in it
is composite of a logarithmic spiral and a straight line. The angle of
intersection of the failure surface with the horizontal plane was determined and found to be different from 45 - ยข/ 2 except in a few cases.
It was also observed that there is an optimum value of width
of tillage tool at which draft per unit width is minimum. In the Bangkok
clay this optimum was found to be 20 cm. |
| Year | 1986 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Other Field of Studies (No Department) |
| Academic Program/FoS | Agricultural and Food Engineering (AE) |
| Chairperson(s) | Gupta, Chandra P. |
| Examination Committee(s) | Singh, Gajendra ;Gee-Clough, D. |
| Scholarship Donor(s) | The Royal Norwegian Government |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 1986 |