Analysis of the dynamics of transport and technological aggregates as variable mass systems

Abstract

Transport in agriculture provides technological processes within the industry, as well as the connection of agriculture with other sectors of the national economy. Due to the late delivery of goods, work is disrupted, the machine and tractor fleet is idle, agricultural products are not exported on time, its quality is reduced, which leads to significant losses. The degree of development of transport and the efficiency of its use largely determine the results of the entire agricultural production. A modern transport and technological unit is a complex dynamic system, the mass indicators of which can be either constant or change during operation (loading or unloading of a semi-mounted transport and technological agricultural machine).
It is proved that the transport and technological unit is characterized by a relatively small average hook load and maximum fluctuations of its amplitudes. The loads that are perceived by the transmission, in some cases, are quite significant, and their amplitudes reach a greater value than the carrying capacity of the parts. At the same time, driving at low speeds is accompanied by continuous rolls of the transport and technological machine onto the tractor. Since the mass of the machine significantly exceeds the mass of the tractor, the vibrations of the dynamic loading of the transmission have an alternating character.
That is why of practical interest is the question of analyzing the actual dynamic loads perceived by the transmission in various conditions of the unit operation when the mass of the latter changes. This will clarify the methods for calculating transmission parts for strength and durability, as well as methods for selecting characteristics of devices used in transmissions to reduce load fluctuations.
To analyze the operation of a tractor as part of a transport and technological unit of variable mass, a semi-mounted machine was considered as a system of material points with constant masses, the composition of which changed: some of the material points left the system (the process of unloading the technological machine is considered). Thus, the concept of a material point of a variable mass is introduced as a set of points that at a certain moment of time are in the region bounded by a certain control surface. Moreover, this area of space in the conditions of the problem, which is considered, can be represented as one that performs translational and/or rotational movement together with a certain geometric point.