محمدرضا کماندار

Some of agricultural operations such as privet stem pruning are slow, repetitive and occasionally dangerous for operators. Almost operators of privet trimmers are exposed to the unpleasant and dangerous arm and body vibrations and sound of pruning machines. The knowing of the shearing behaviors of privet stem have an important role in the design and fabricate of suitable pruning machine. So a series of experimental tests were performed to measure the shear force, shear consumption energy and shear strength of stem internodes of privet stalk under quasi-static and impact cutting at different loading rate, different internode position and moisture level 58% wet base. In the quasi-static cutting test, the stalk specimens were cut in the quasi-static process at four loading rates: 5, 10, 15 and 20 mm min-1 and three internode positions: fifth, tenth and fifteenth. In impact cutting test, the stalk specimens were served in impact process at four loading rates: 1, 2, 3 and 4 m s-1 and three internode positions: fifth, tenth and fifteenth. In quasi-static cutting, the variance analysis of the data indicated that the loading rate created significant effect on shear strength and shear consumption energy in probability level of 5%. Also the internode position and the interaction effect of loading rate and internode position, created significant effects on shear strength and shear consumption energy in probability level of 1%. Based on the statistical analysis, the average values of shear consumption energy and shear strength were obtained as 556.70 J from 95.35 to 1567.95 J and 29.12 MPa from 19.63 to 37.04 MPa respectively. In impact cutting, the variance analysis of the data results showed that the effects of loading rate, internode position and interaction effect of loading rate on internode position, created significant effect on shear consumption energy and shear strength in probability level of 1%. The data statistical analysis showed the average values of shear consump