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.

Keywords

Afkari-Sayyah, A.H. and Minaie, S. 2009. Fundamentals of Investigation and Evaluation of Mechanical Damage in Agricultural Products. 1st Ed., Jahad-Daneshgahi Pub. 184 pp., Ardabil, Iran, (in Farsi).
Afkari-Sayyah, A.H. and Minaie, S. 2004. Behavior of wheat kernels under quasi-static loading and its relation to grain hardness. J. Agric. Sci. Technol. (JAST). 6, 11-13.
 
اثر بررسی اثر رقم، اندازه و رطوبت دانه...
 
Anon. 2009. Government Information Database. Available at: http://www.dolat.ir/NSite/FullStory, (in Farsi).
Arnolds , P.C. and Mohsenin, N.N. 1971. Proposed techniques for axial compression tests on intact agricultural products of convex shape. T. ASAE. 14, 78-84.
ASAE Standards. 1999a. Compression test of food materials of convex shape. Am. Soc. Agric. Eng. S368.3.
ASAE Standards. 1999b. Moisture measurement - unground grain and seeds. Am. Soc. Agric. Eng. S352.2.
Bargale, P. C., Irudayaraj, J. and Marquist, B. 1995. Studies on rheological behavior of canola and wheat. J Agric. Eng. Res. 61, 267-274.
Bargale, P.C. and Irudayaraj, L. 1995. Mechanical strength and rheological behavior of barley kernels. Int. J. Food Sci. Technol. 30(5): 609-623.
Henry, Z. A., Su, B. and Zhang, H. 2000. Resistance of soya beans to compression. J. Agric. Eng. Res. 76, 175-181.
Hoseney, R.C. and Faubion, J.M. 1992. Physical properties of cereal grains. In: Storage of Cereal Grains and Their Products. 4th Ed. Americ. Assoc. Cereal Chem., Inc. St. Paul, Minnesota, M.N.
Molenda, M. and Stasiak, M. 2002. Determination of the elastic constants of cereal grains in a uniaxial compression test. Int. Agrophysics. 16, 61-65.
Moya, M., Ayuga, F., Guaita, M. and Aguado, P.J. 2002. Mechanical properties of granular agricultural materials considered in silos design. 15th ASCE Mechanics Conference, 2-5 June, Columbia University, New York.
Stroshine, R. and Hamann, D. 1994. Physical Properties of Agricultural Materials and Food Products. 1st Ed. West Lafayette, IN.
Timoshenko, S.P. and Goodyier, J.N. 1970. Theory of Elasticity. 3rd Ed. McGraw-Hill, New York, 416 pp.