Determining Some Mechanical Properties of Chickpea to Use in the Design of its Harvesting Machines

The objective of this study was to determine some mechanical properties of chickpea which are basic with regard to the design of harvesting machines. At the present, chickpea is harvested manually with difficulty and low efficiency. Therefore two common methods in grain harvesting were studied meanwhile stem cutting force and pods stripping force were compared in the field and greenhouse conditions. The relationship of stem diameter and moisture content with shear stress was verified by the linear regression analysis. There was no significant difference between shear stress of chickpea stems planted in the greenhouse and field conditions and it varied from 2.8 to 9 MPa depending on the stem diameter. At 10.5 to 19% moisture content, there was no significant effect of moisture content on shear stress but the regression analysis showed that the effect of stem diameter on shear stress was significant. In terms of pod stripping force a significant difference was observed between greenhouse and field environments. The average of this force in the field and greenhouse were 8.8 and 6.2 N, respectively, at 12% moisture content (w.b.). As the field results did not correspond with those of the greenhouse for stripping, it can be concluded that greenhouse data may not be suitable for designing purposes and researchers should use the data from field condition.