PHYSICOMECHANICAL PROPERTIES OF IRON TREE SEED (PROSOPIS AFRICANA) FROM SOUTH EASTERN NIGERIA.

Abstract

Selected physical and mechanical properties of Iron tree seeds (Prosopis africana) were studied at three moisture content levels of 10%, 15% and 20% (db). Compression strength characteristics were conducted under quasi-static compressive force at vertical and
horizontal loading positions and the rupture forces, compressive strength, modulus of deformability, toughness, stiffness and force at bio-yield point determined as the mechanical properties. Results indicated that volume (0.088 - 0.503mm³), surface area (0.237 -
0.754mm²), geometric mean diameter (0.273 - 0.487mm), and weight (0.185 - 0.252g) of the velvet bean seed increased linearly with increase in moisture content and bulk density and specific gravity (2.341 - 0.571g/mm) decreased linearly with increase in moisture content. These indicate that Iron tree seeds (Prosopis africana) have wide size ranges and no single sample of the grains can effectively represent the other. In the case of the force-deformation characteristics, result indicates that the force and corresponding deformation to rupture of velvet bean seeds were found to vary from 257.825N - 368.750N and 1.110mm - 1.700mm in longitudinal (vertical) loading positions and 115.75N - 310.938N, 0.475mm - 1.563mm in lateral (horizontal) loading positions at the various moisture contents. The bio-yield force, compressive strength and toughness of the velvet bean seeds varied from 125.000N - 175.000N, 0.648KN/mm - 3.470KN/mm and 1.167KJ/mm - 7.709KJ/mm respectively in longitudinal loading positions to 82.813N - 160.938N, 0.641KN/mm - 0.890KN/mm and 1.294KJ/mm - 1.633KJ/mm respectively in lateral loading position at the various moisture contents. Generally, the compressive strength of the Iron tree seeds (Prosopis africana) is higher at lateral loading position than at the longitudinal loading position.