Effect of loading rate and moisture content on the fracture resistance of beechwood (Gmelina arborea) seed

Abstract

Mechanical properties of agricultural materials are necessary for the proper design and development of their planting, harvesting, handling and processing machineries. In this research, fracture resistance of whole gmelina seed was evaluated in terms of its rupture force, rupture energy and deformation at rupture under four moisture content levels and three loading rates. The quasi-static compressive tests were conducted at 20, 25, 30 and 35 percent moisture levels (wb); and 5, 10 and 15 mm/min loading rates. Based on the results obtained, moisture content and loading rate had significant (P ≤0.05) effect on all the three parameters investigated. The force required for initiating seed rupture decreased with increase in moisture content and loading rate. The highest rupture energy was 0.268 Nm at 35% moisture content under 5mm/min loading rate, and the lowest was 0.116 Nm at 20% moisture content under 15 mm/min loading rate. In addition, the deformation capability of the seed decreased from 1.017 mm at 35% moisture content (wb), under 5 mm/min loading rate, to 0.458 mm at 20% moisture content (wb) under 15 mm/min loading rate. The results obtained from this research would be useful in the design and development of machines used in gmelina seed processing operations.

Keywords: Gmelina seed, Fracture resistance, Moisture content, loading rate