SELECTED MOISTURE DEPENDENT FRICTION PROPERTIES OF TWO AFRICAN YAM BEAN (SPHENOSTYLIS STENOCARPA) ACCESSIONS

Abstract

Friction properties such as angle of repose, coefficient and angle of internal friction, and coefficient of frictionon material surfaces of two African yam bean accessions (TSs 137 and TSs 138) at moisture content levels of 4, 8, 12 and 16%wet basis (w.b.) were determined for use in the design of planting, processing, handling, and storage equipment. For this study,2 4 factorial in Complete Randomized Design (CRD) and Split Plot in Randomized Complete Block Design (RCBD) wereemployed. The angle of repose was measured using the cylinder method. The coefficient of friction was measured by the forcerequired to slide a cell filled with African yam bean on the material surface. Coefficient and angle of internal friction weredetermined by providing a grain bed instead of material surface. The angle of repose and coefficient and angle of internalfriction showed an increase with an increase in moisture content. The angle of repose increased from 17.47 to 26.07. for TSs137 and 15.71 to 35.38. for TSs 138. The coefficient and angle of internal friction for the two accessions ranged from 0.59to 0.78 and 30.41 to 38.11., respectively. The coefficient of friction on material surfaces ranged from 0.30 to 0.60 for allaccessions, material surfaces, and moisture contents. The effect of material surface on coefficient of friction and moisturecontent on all friction properties was highly significant (p < 0.05). The two accessions were statistically different (p < 0.05)with respect to angle of repose and not statistically different with respect to coefficient of friction on material surfaces and coefficient and angle of internal friction.