عنوان مقاله [English]
نویسندگان [English]چکیده [English]
This study was conducted to develop the appropriate equations for predicting draft and vertical forces on a chisel tine using Dimensional Analysis Technique. Tests were carried out in the soil laboratory of the Agricultural Engineering Research Institute, Karaj, Iran. The effects of four levels of rake angle (10, 15. 20 and 25degrees), three levels of forward speed (1.5, 3, and 4.5 kmh-1 )and three levels of tine aspect ratio (1.5, 2, and 3) on horizontal and vertical forces acting on a chisel plow tine (100 mm wide) were investigated. The study was conducted in a loamy soil with 14% (d.b.) moisture content. The treatments were arranged in a randomized complete block design as a 4 by 3 by 3 factorial of three replications. Results of F-test (5% probability) indicated no significant differences between values of slope and intercept of the measured vs. predicted values plot as compared with 1:1 line plotted. The statistical indices; NRMSE and MBE emphasize precision of the adopted analytical model. In addition, other results of the study showed an increasing trend of draft force for variation in input parameters. This finding is supported by similar results derived from ASAE general equation .