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
Highlights
Gmelina arborea (Gmelina arboreal Roxb) is a fastgrowing tree, which grows on different localities and prefers moist fertile valleys, they attain moderate to large height up to 40 m and 140 cm in diameter (Tewari, 1995)
Rupture Energy (Toughness): The results showed that the energy needed to rupture the gmelina seed was a function of both moisture content and loading rate (Figure 2)
For product quality and energy conservation, it is recommended that seeds should be cracked at lower moisture content and higher compressive loading speed. This is because, trying to crack the seed at higher moisture content, the seed will experience larger deformation, resulting in breakages and poor product quality. This present study was carried out to investigate the impact of loading rate and moisture content on the fracture resistance of gmelina seed
Summary
Gmelina arborea (Gmelina arboreal Roxb) is a fastgrowing tree, which grows on different localities and prefers moist fertile valleys, they attain moderate to large height up to 40 m and 140 cm in diameter (Tewari, 1995). Mamman and Umar (2005) studied the effects of moisture content and loading orientation on the mechanical properties of balanites nuts. They reported that the six mechanical properties investigated (modulus of elasticity, bioyield point, bioyield stress, compressive strength, rupture strength and modulus of stiffness), decreased with increase in moisture content. Saiedirad et al (2008) studied effects of moisture content, seed size, loading rate and seed orientation on force and energy required. The objective of this study was to investigate the fracture resistance of gmelina seed at different moisture contents (20, 25, 30, and 35% wb) and loading rates (5, 10 and 15 mm/min). This is to evaluate the impact of moisture content and loading rate on the fracture resistance of gmelina seed, which is essential for the design and development of gmelina processing machines
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