Document Type : Original Article
Authors
Abstract
Design of agricultural machinery and implements for local needs, requires determination of accurate values of physical and mechanical properties of soil, including soil-metal friction coefficient. In this study, the effects of soil moisture content at five levels and sliding speed (at three levels of 0.5, 2.5 and 3.5) on four contact materials namely: steel, cast iron, rubber, and Teflon on the soil- metal external coefficient of friction of of loam, sandy loam and loamy sand soil at 5 levels of soil moisture content was investigated In this context a device was designed and evaluated for accurate determination of soil friction coefficient. Data were analyzed based on 5×4×3 factorial experiment in randomized complete block design using MSTATC software. Due to differences in moisture content at different phases of friction, adhesion and fluid in soils with different textures, statistical analysis was performed separately for each soil texture and nested factorial design was used to study the effects of soil texture. Results showed that in all soil types, three sliding speed levels affected soil-metal friction significantly at the probability level of 1%. Also, with increasing sliding speed, soil-metal friction coefficient had incremental trend. Meanwhile, the results also showed that at the experimental sliding speeds of 0.5, 2.5 and 3.5 cm/s, the trend and pattern of the curves of soil friction coefficient versus soil moisture content were similar. Results of this study and the determined values of parameters of soil-metal friction coefficient and adhesion could be used in the design of agricultural machinery and implements, modeling of the relationship between soil & machine, draft calculation and also in tillage implements performance and their wear and tear investigations.
Keywords
Proceeding of 5th International Congress Soil Science. Aug. 16-21. Leopoldville, Congo. 2, 35-45.
New York, USA.
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