A classification is given of methods for studying the process of interaction of soil environments with the tillage tools of soil-cultivating machines. The methods are divided into two groups: mathematical modeling and experimental research. Mathematical methods for studying soil interactions using numerical modeling methods that allow one to overcome the shortcomings of analytical and empirical approaches are considered in more detail. A classification, existing software, and an analysis of the possibilities of continuous and discrete numerical methods are given. Studies were performed using continual methods are analyzed: finite element method (FEM) and computational fluid dynamics (CFD). Also studies using discrete methods are considered: the discrete element method (DEM) and the smooth particle hydrodynamics (SPH). An analysis of existing studies has shown that the finite element method can be used for cohesive soils, making it possible to obtain both strength characteristics and data on the process of destruction and displacement of the soil massif. The computational hydrodynamics method can be effectively applied only to the study of the power characteristics of overmoistened soils. Attempts to extend this approach to a wider range of soils lead to significant errors. Discrete methods are most versatile and reliable. So the method of discrete elements allows to reliably assess both the power and quality characteristics of the tillage process. For example, the shape of the transverse profile, the degree of loosening (compaction) of the soil, the nature of mixing of the soil layers.
The problems of studying the static lateral stability of machine-tractor units by the methods of multi-body dynamics (MBD) are considered. To create a simulation model, the virtual modeling method in CAD SolidWorks and CAE SolidWorks Motion was used. A 3d model of the MTZ-82.1 tractor was created, equipped with front and rear mounted three-point linkage. At the same time, all the basic structural elements and their geometric and mass-inertial parameters were preserved. The tractor was aggregated with front and rear mounted modular implements. To study the lateral stability, the tractor is mounted on a virtual stand consisting of a fixed base and a platform that changes the angle of inclination. Using a virtual stand, the lateral stability angles of three typical configurations of a machine-tractor unit and a tractor without attachments were obtained. For a tractor without attachments, the rollover angle was 34°, it was equipped with a single-beam rear mounted implement 36° (scheme 0 + 1), with a double-beam rear mounted implement 25° (scheme 0 + 2), with a front mounted implement and a double-beam rear mounted implement 36° (scheme 1 + 2). Verification of simulation data was carried out by comparing with experimental data obtained at a stationary stand. The difference in the values of the critical angles of lateral stability of the tractor, obtained by the results of virtual modeling and using the method of rollover the tractor on a stationary stand, is 3 … 5°.
The problems of studying the dynamic stability of machine-tractor units by the methods of multi-body dynamics (MBD) are considered. To create a simulation model, the virtual modeling method in CAD SolidWorks and CAE SolidWorks Motion was used. A 3d model of the MTZ-82.1 tractor was created, equipped with front and rear mounted three-point linkage. The tractor was aggregated with modular implements. To test the machine-tractor unit, a test track was simulated, consisting of four sections with various non-movable obstacles: single linear; single sequential; group linear; group sequential. In the process of modeling, the following parameters were recorded: lifting height of the geometric center of the wheels; displacement of the machine-tractor unit center of gravity in the transverse direction; linear speed. An analysis stages movement of the machinetractor unit showed that overcoming a single linear, single sequential and group linear obstacles at a speed of 0.9 m/s occurs without loss of stability. Only when overcoming a group sequential obstacle, significant oscillations in the tractor frame are observed, however, due to the balancing suspension of the front wheels, they do not always lead to the rollover of the tractor. In the future, using the developed virtual stand, it is possible to carry out studies of the dynamic stability of various configurations of a machine-tractor unit. It is also possible to change the geometry of obstacles, the angles of inclination of the support surface, the speeds of motion, the contact parameters of the wheels, etc.
The search for energy efficient tillage technologies and the creation of more advanced machines while reducing the cost of the final product are one of the priority goals. One step in the development of tillage implements is to develop a theoretical basis. In this case, mathematical or simulation modeling is used, but part of the work carried out in the laboratory and in the field is an integral part of the research structure. Of great importance in testing forestry equipment are dynamometer methods, which consist in measuring the forces transmitted from the engine to the machine or acting on the working bodies and parts of the machines. This is especially true for forest implements that interact not only directly with soils, but also with roots, branches, stumps and other components of forest soils. The article is presented in the form of an analysis of the structures of dynamometric installations used to conduct research on tillage equipment. Also given are the designs of installations used for research of combined machines with active working bodies, such as a forest fire engine. Particular attention is paid to structures for volumetric dynamometry (2D and 3D).
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