effects of normal pressure, sliding velocity and moisture content of chickpeas on dynamic friction coefficient on steel surfaces

in this research, an apparatus was made and utilized to determine the friction coeffi-cient of chickpea grains on steel surfaces. experiments were carried out on two black and galvanized surfaces and at four sliding velocities of 5, 20, 100 and 500 mm/min, at three moisture content of 7.5%, 15% and 21% wet basis (w.b.) and at three vertical pressure values of 14.28, 100 and 150 kpa. the following results were obtained. 1) for surface conditioning, the steel plates need to be passed through the grains for at least 7 times. 2) at low sliding velocity, by increasing the velocity from 5 to 20 mm/min, the dynamic friction coefficient of chickpea grains increased, and at a sliding velocity of 500 mm/min it was decreased. 3) for the black steel surface, by increasing the moisture content of chickpea grains from 7.5% to 15% w.b., the value of the friction coefficient in-creased; but at a moisture content of 21% w.b., it decreased. for galvanized steel sur-faces, and sliding velocities of 5 and 20 mm/min, increasing the moisture content, the value of friction coefficient was found to decreased, but for sliding velocities of 100 and 500 mm/min it’s behaviour was similar to the black steel surface. 4) normal pressure has no significant effect on the friction coefficient (at 0.01 level) and the difference between the mean values of the coefficient of friction associated with the normal pressure of 14.28 kpa and 100 kpa, as well as 100 kpa and 150 kpa was not significant at the 0.05 signifi-cance level.