Document Type : Research Paper
Abstract
Engineering analysis for the design and modification of mechanical systems in grain harvesting and processing, including barley, depends on basic information about the physical and mechanical properties of the agricultural commodities. These properties vary significantly with the biological nature of agricultural materials under varying conditions (variety, shape, size, moisture content, etc.). This research project conducted 300 compression tests to extract two important parameters of grain strength and used statistical analysis to determine their effects. The results showed that variety and moisture content have significant effects on modulus of elasticity and contact stress (p<0.01), while the effect of grain size was not significant. Increasing moisture content decreased contact stress (linearly) and modulus of elasticity (S-shape curve). Accordingly, 17% moisture content (w.b.) was considered as the transition moisture in barley grain. Values greater than this caused the grain to be softer and values less than this made it more brittle. The range of maximum stress induced in the barley grain in the elastic range was 243 MPa at 25% MC to 2832 MPa at 10.2% MC. Maximum contact stress varied from 11.3 MPa to 455.4 MPa for different treatments.
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