The aim of the research is to reveal and study basic physical parameters of vegetative materials characterizing their wear properties and resistance to cutting, and to assess their impact on the process of cutting of free standing stems of plants. The analysis of results of theoretical and experimental study on without-prop cutting obtained by the leading scientists in this field was done. It was established that considered substantiations of without-prop cutting of free standing stems of plants didn’t account all physical parameters of vegetative materials characterizing their wear properties and resistance to cutting. Also in these studies normal cutting was considered (stab of a blade is directed perpendicularly to longitudinal axis of stem). In real conditions cutting of a stem may occur not only at the right angle, for example at cutting the vegetation of canal and hilly terrain slopes. For reasons given, the author proposes that during vegetation cutting by a knife blade directed at the right angle to longitudinal axis of a stem the compression force and tensile strength of a stem resist to cutting. During the study the cases of cutting free standing plant stems by a knife blade of cutting apparatus directed top-down and bottom-up were considered. It was revealed that at bottom-up knife rotating the breaking strength of stem fibers resists to cutting process. And at a top-down knife rotating the longitudinal compressive force of a stem resists to cutting process. This force is many times smaller than the longitudinal tensile strength. The conclusion was done that without-prop cutting of free standing stems of plants by the knives directed top-down has benefits for significant energy savings.
Keywords: without-prop cutting, knife, knife blade, plant stem, cutting force, critical cutting force, tensile strength, compression force, experiment.
