Mechanical Behaviour of Bulk Seeds of Some Leguminous Crops under Compression Loading

Abstract

The behaviours of constrained bulk columns of seeds of 3 important leguminous feed crops under compressive force applied at a uniform rate of 10 mm min-1 up to 100 kN at 9% moisture content (in dry basis) were studied to establish parameters which are relevant to the design of equipment for achieving product densification. Deformation varied significantly (P < 0.02) with crop type and was the highest in lupine seeds. Feed pea had the highest strain resistance value. Both deformation energy and volume energy requirements varied significantly (P < 0.0001) with crop type. Moduli of deformation of compressed feed pea, lupine, and soybean at an applied force of 100 kN were 269.7, 306.3, and 455.2 MPa, indicating the proportionate resistance of the crop materials to compressive strain. Precisely 4.43, 3.76, and 3.15 MJ m-3 are required to achieve 56.7, 77.0, and 67.7% or 461.7, 539.3, and 500.4 kg m-3 gains in bulk density in feed pea, lupine, and soybean, respectively. Deformation and volume energy demands correlated negatively (r = -0.934 and r = -0.78) with lipid presence. Crops with more oil appeared to deform more easily under compressive force. Higher deformations and lower energy demands may be possible at optimal combinations of force, product moisture, and depth.