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چکیده
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The lack of synchronicity in the ripening of the sesame capsules causes an increase in seed
loss at the time of harvest by existing machines. Little information is available concerning
the effect of sesame stalk properties on the performance of impact cutting machines. To
design a new and better sesame harvesting machine, real-time shear force and specific
shear energy of sesame stalks in the impact cutting process were modelled and investigated.
A series of laboratory and field tests were performed to model and measure the
shearing properties of the stalk at the three moisture levels of 15, 30, and 60%, on a wet
basis, at the four cutting speeds of 0.5, 1, 1.5, and 2 m s1, and the three stalk positions of
upper, middle, and lower region. The results of laboratory tests showed that at moisture
content of 15%, the ratios of cutting force at the loading rate of 0.5e2 m s1 are about 58%,
55%, and 40% and the ratios of specific shear energy are about 66%, 37%, and 39% at the
upper, middle, and lower regions, respectively. Also, at the moisture content of 60%, the
ratios of cutting force at the loading rate of 0.5e2 m s1 are about 66%, 78%, and 83% and
the ratios of specific shear energy are about 50%, 33%, and 30% at the upper, middle, and
lower regions, respectively. Finally, to determine the maximum impact cutting force on the
sesame field, the variation of impact shear force was modelled by an equation and the
results of field tests showed that the maximum cutting force can be calculated by the
equation and simple pendulum arm on the sesame field. When the characteristics of the
physical characteristics of the sesame stalk are known, it is possible to calculate the
maximum force for impact cutting of the stalks on the sesame field using a simple
pendulum arm.
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