| Author | Govinddas, Shah Narendra |
| Call Number | AIT Thesis no.AE-80-20 |
| Subject(s) | Agricultural machinery--Testing
|
| 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 | Floats associated with machineries in wet land fields may improve their performance in wet puddled soils. The investigation was carried out to find more about the mechanics of operation of these kind of devices in soft, wet, clay soils.
The aluminum model floats were tested in a specially designed soil bin system, with a constant speed of 0.33 m/sec. Float performance was compared
on the basis of drag requirement to tow the float on typical rice soils. The Bangkok clay soil was processed to give same measured soil constants
throughout the tests. The following were found:
(1) a long and narrow float gave less coefficient of drag than short and wide; for the same base area, and the same load.
( 2) the coefficient of drag is reduced by about 35% at all 5 sets of normal loadings tested; when the point of application is shifted 1/4 of float length back from centre.
(3) changing the bow shape from a flat nose to a raised nose reduced the drag coefficient from 1.1 to .59 at normal pressure of 0.89 kN/sqm. and from 0.83 to 0.54 at 1. 78 kN/sqm. normal pressure.
(4) a substantial reduction in drag force resulted when the surface was covered with a thin water film.
The measured values of sinkage modulus (K) and exponent of sinkage (n)
were substituted to calculate the theoretical drag due to soil compaction,
which yielded very low forces compared to that measured indicating that
soil-metal friction was responsible for the major part of the drag force.
The performance of a free rolling wheel and track of similar dimensions was predicted from measured soil constants and was compared with float performance. The float seems to perform worse on sticky soil with no water on the surface, The float on a water covered surface gave a smaller coefficient of drag than the coefficient of rolling resistance. The presence of this water film is therefore crucial to the performance of floats in soft soils. |
| Year | 1980 |
| Type | Thesis |
| School | School of Environment, Resources, and Development |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Agricultural and Food Engineering (AE) |
| Chairperson(s) | Gee-Clough, D.
|
| Examination Committee(s) | Singh, Gajendra ; Konaka, Toshio
|
| Scholarship Donor(s) | Government of Norway |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 1980 |