Comparative Study of Engineering Properties of Four Selected Cowpea (Vigna Unguiculata) Varieties

Poor mechanization of cowpea (Vigna unguiculata L. Walp.) in Nigeria is due to unavailability of handling machine due to large number of variations in engineering properties of the crop. To design a functioning machine for the mechanization of the crop, engineering properties of its local varieties is needed. The four local varieties selected are Small White, Big White, Drum and Milk cowpea. The selected engineering properties investigated are size, shape, weight, density, bulk density, angle of repose and coefficient of friction. The seeds were bought from Wаѕо market in Ogbоmоѕо, Oуо State Nigeria. The selected properties were measured using standard methods. The results of the experiments showed that; Mean Length; small white (7.99 mm), milk (10.30 mm), big white (10.40 mm) and drum (10.71 mm); Breadth; small white (6.53 mm), milk (7.37 mm); big white (7.60 mm) and drum (7.98 mm);Thickness; milk (5.00 mm); small white (5.41 mm), drum (5.61mm), and big white (5.92 mm); Unit weight; drum (0.63 g), small white (0.64 g), big white (0.56 g), and milk (0.63 g); Sphericity; milk (0.70), drum (0.74), big white (0.78) and small white (0.82);Angle of repose, small white (26.01), big white (26.05), drum (24.16) and milk (27.52).The average values of static coefficient of friction on the different verities (mild steel, stainless and glass) were, small white (0.45, 0.44, 0.42); big white (0.45, 0.44, 0.44), milk (0.44, 0.44, 0.43) and drum (0.45, 0.44 and .044) respectively. The results from this experiment showed that in the design and manufacturing of operating system for handling and processing of the crop, effect of engineering properties of different cowpea varieties must be incorporated. Keywords: Engineering properties, cowpea, design, processing equipment, manufacturing, verities.