Determination of dynamic friction coefficient in common wheat varieties on different contact surfaces

Abstract

Dynamic friction coefficients of agricultural crops are applied in designing silos, agricultural crops storage structures, transporting, handling machines and discharging implements.  In this study, at first an apparatus for measuring dynamic friction force was developed, then the dynamic friction coefficient of common wheat varieties at five levels (Azar2, Rasad, Sardari, Zagros, Sabalan) were investigated on contact surface at four levels (black, galvanized, mild and aluminum sheets), with sample slipping speed at three levels (5, 10 and 15 cm s^-1) and grain moisture content at three levels (12%, 14% and   18% w. b.).  The data were analyzed probability.  The obtained results revealed that the main effects of all independent factors as well as the double interactions on the dynamic friction coefficient were significant (P<0.01).  Also, the results revealed that with an increase in the grain moisture content from 12% to 18% w. b., the dynamic friction coefficient mean increased from 0.249 to 0.335.  And also with an increase in the samples slipping speed from 5 to 15 cm s^-1, the dynamic friction coefficient increased significantly from 0.265 to 0.298.  Among the contact surfaces, the highest mean value (0.331) and the lowest mean value (0.248) allocated to black and galvanized sheets, respectively.  Also, among the varieties, the highest (0.299) and the lowest (0.273) mean values allocated to Azar2 and Zagros varieties, respectively.