Engineering properties of Dioclea reflexa (Hook F.) seed relevant to machine processing and bulk handling

Abstract

Interest is growing in the utilization of fringe plant materials such as Dioclea reflexa seed to cater for the need of growing global population. It has demonstrated potentials for a wider use as human food, and as industrial raw material. This research focused on determines the engineering properties of the seed that will be useful in the design or selection of industrial machinery for its processing and bulk handling. Four types of tests were carried out on the seeds: geometric, gravimetric, frictional and mechanical tests. Results revealed that the seed's mean geometric diameter was 25.84mm at 5.60 % (w.b.) moisture content. The individual seed average mass, true density and bulk density were 7.76g, 948.5kg.m-3 and 558.5kg. /m3 respectively. Among the surfaces tested, glass has the lowest coefficient of friction (0.221) while wood has the highest (0.424). Seed orientation during compression test has effect on fracture force, deformation, toughness as well as energy absorbed. Variation of mechanical properties along axes of orientation in quasi-static compression of the seeds showed that major axis has the highest mean fracture force, mean deformation to fracture, and mean fracture energy at 1.38kN, 3.05mm and 2.10J respectively. However, the axis with the highest strength is the minor axis at 1.01kNmm-1 . From energy efficiency point of view, when designing machine for cracking the seeds, provision must be made for the seeds to be oriented in such a way that the applied cracking force will impact the seeds along their major axis.