بررسي تاثير سرعت و زاويه لبه تيغه بر مقاومت برشي ساقه ارقام مختلف برنج

Investigating the Effects of Velocity and Blade Bevel Angle on Stem Shear Strength of Different Rice Varieties

An experimental dynamic shear test apparatus with reciprocating mechanism was designed and constructed to measure the shear force of paddy stem. The effects of shearing velocity at four levels (0.6, 0.9, 1.2 and 1.5 m/s), and three levels of blade bevel angle (25, 30 and 35 degree) were also investigated on shear strength of four Iranian varieties of paddy, including ʹKhazarʹ, ʹFajrʹ, ʹHashemiʹ, and ʹBinamʹ. Analysis of variance of the data indicated that all the main effects of treatments as well as interaction between variety and shearing velocity affected the shear strength at 1% level of confidence. The maximum and minimum values of shear strength were related to the varieties ʹKhazarʹ and ʹHashemiʹ, with mean of 0.210 MPa and 0.181 MPa, respectively. The results of Duncan test indicated no significant differences among the levels of shearing velocity at 0.6 mis and 1.5 m/s at 1% level. The maximum and minimum shear strength were 0.226 MPa and 0.155 MPa for shearing velocities of 0.6 nvʹs and 1.5 mis. respectively. The diference between levels of blade bevel angle was not significant. Interaction between variety and shearing velocity had significan difference on shear strength. The maximum and minimum shear strength were related to ʹFajrʹ with mean of 0.234 MPa at 0.6 m/s, and ʹBinamʹ with mean of 0.137 MPa at 1.5 m/s, respectively.