2016, № 58

UDC: 631.362.2
GSNTI: 30.15.35

To methodology of study of motion and work of machines, their power balance taking into account the law of change of kinetic energy of the mechanical system and operating forces

The methodical approach to the justification of the energy efficiency of mechanized production processes based on the study of movement and the work of tractor units (MTA), their energy balance, taking into account the law of change of the kinetic energy of the mechanical system and the operating forces is presented. The main problems of the dynamics of mechanisms and machines are considered: the study of the motion of the ITA taking into account the forces applied to their links and forces resulting from movement; equations of motion of the machine in the form of change of the kinetic energy and its characteristic periods of motion; the law of transfer of work and medium capacities in machines; energy balance of the machine-tractor unit depending on the nature of the connection of its constituent mechanisms and gears (series, parallel and mixed connection); the law of the transmission of forces and moments in a steady motion. Two types of forces are proposed acting on the links of mechanisms: counterbalancing and unbalancing. Counterbalancing forces - the forces that are being applied to the links of the AIT in a state of rest can not withdraw it from this state - that is, let it move. The same forces applied to the MTA while it is in motion can not change its kinetic energy. Therefore, the MTA under the influence of these forces will make its special movement - movement that is not accompanied by a change in kinetic energy. Unbalancing forces - the forces that drive the AIT, at rest, and being attached to the moving AIT change its kinetic energy. In turn, the steady motion includes two types of movement - equilibrium and nonequilibrium. Nonequilibrium steady movement is the movement with theconstant average for the period kinetic energy due to the action of unbalancing forces. The equilibrium steady motion is the motion with constant instantaneous kinetic energy, as occurring under the influence of countervailing forces. The distinctive feature of the equilibrium motion MTA is that inertia forces arising in the AIT mechanism with that kind of movement, after bringing them to the point of bringing the machine give the total reduced force of inertia equal to zero. Therefore, if you have in AIT equilibrium motion dynamic traffic laws of the transmission of forces and moments take the form of static laws, thus consideration of these laws appears possible in principle to dispense without the forces of inertia. Normal operating mode of the machine, including the starting and stopping periods flow under the influence of unbalancing forces and hence accompanied by a change of kinetic energy. To study the MTA motion the most convenient is the theorem of the system kinetic energy change, while the variation of the kinetic energy of the system is called the equation of machine motion. According to the law the transfer of work in machines with steady motion (equilibrium and nonequilibrium) driving forces work for the period is spent entirely on the work of the forces of good and bad resistance. Analyzing the energy balance of the unit, the important conclusion is made that in the case of serial and parallel transmissions overall efficiency depends on the number of parallel branches in the unit, the distribution work for each of the parallel branching and the number of successive transmissions in each parallel branch. The representation of the law of the transmission of forces and moments in the steady motion is given that takes place in matters relating to the definition of the traction resistance of the working machine, the effort on the power tools hook, etc. Therefore, from the equations of motion an expression is obtained directly containing the forces and moments, when the basis is the equation of motion in the form of kinetic energy for translational and rotational motions of the machine units.
Keywords: Dynamics, movement, kinetic energy, mass, instantaneous power, mechanical system, mechanism

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Authors:

Kourasov Vladimir Stanislavovich, Dr. of technical sciences, Professor, head of the department; Department of tractors, cars and technical mechanics, Kuban State Agrarian University.
Pleshakov Vadim Nikolaevich, Dr. of technical sciences, Professor; Department of tractors, cars and technical mechanics, Kuban State Agrarian University.
Samurganov Evgeny Ermanekosovich, undergraduate; Department of tractors, cars and technical mechanics, Kuban State Agrarian University.
Ponomarev Artem Vasilyevich, applicant; Department of tractors, cars and technical mechanics, Kuban State Agrarian University.