Physical Properties and Dynamic Shear Strength ofPaddy Stem

摘要

The paddy plant is subjected to natural loadings throughout the growing season andsevere mechanical treatments during harvesting. In order to aid in the engineering design of theharvesting machines, there is a need for more information concerning the physical andmechanical properties of paddy stems.In this study, physical characteristics such as, linear density, cross-sectional area and moisturecontent of stems as well as their effects were determined and investigated on the cuttingproperties of paddy stem.A shear apparatus with reciprocating mechanism was designed to measure the cutting force. Afactorial experiment in the form of Randomized Complete Block Design (4×3×2) with fourreplicates was used to determine the effects of variety (Fajr, Hashemi, Khazar, and Binam), bladecutting speed (0.9, 1.2 and 1.5 m/s), and blade type (smoothed-edge and serrated-edge) on theshear strength of paddy stem.The results indicated that the cutting force increased with increase of linear density andcross-sectional area and decreased with increase of moisture content. Based on thestatistical analysis results, variety and cutting speed affected the shear strength at 1%level of confidence. The difference between shear strength of varieties was significant.The maximum and minimum shear strength was related to the varieties of ' Kazar' and' Hashemi' with average of 187.4 and 163.5 Kpa, respectively. The shear strength