Determination of minimal cutting speed by flailing potato vines
Godesa, T. (Ljubljana Univ. (Slovenia). Biotechnical Fac., Agronomy Dept.)
Mathematic model was developed to determine minimal cutting speed of flail knives at potato vine killing using special flail mower. Model bases on bending moment equilibrium and depends on mechanical properties of material to be cut, and height of cut level, as well as height of stalk. Mechanical properties of potato stalk were measured and through the model calculated values were compared with experimental results. Average shear strength of potato stalk was 2.07 N/mm2 and Young's modulus 51.23 N/mm2. Calculated minimal cutting speeds were from 4.01 to 11.8 m/s, depended upon different height of cutting level and centre of stalk mass. By flailing the potato vines with cutting speeds 6.2, 11.6 and 17.6 m/s, the average percentages of cut off stalks were 35%, 68% and 88% and lengths of rest part of stalks were 23, 20 and 10 cm respectively. The experimental results refected, that the predicted values of cutting speed showed good agreement with experimental values, therefore such mathematical model should be used to estimate the minimal required cutting speed at flailing potato vines.
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