Machines and equipment for asphalt pavement milling are widely used throughout the world. With the growth of road construction, the demand for this class of machinery also rises. At the same time, the optimization of design and technological parameters of the milling machines is impossible without a comprehensive study of processes of milling asphalt concrete with the working elements of a cutter. The article provides a brief overview of different approaches to find out the loads on the working bodies of various machines, as well as indicates the advantages and disadvantages of these approaches. We describe the design of a pendulum stand used to study the processes of milling asphalt concrete with a single tooth cutter. We also describe the method of operation of such a stand. The design of the pendulum stand allows us to determine the cutting work, the average, and the instantaneous cutting forces. The work also provides the result of tests of cutting elements during their interaction with samples of asphalt concrete of different grades that are widely used in road construction. We also show the non-linear dependence of cutting resistance forces on the temperature and thickness of penetration of a cutting element. It is noted that working with a slight tooth penetration leads to low energy efficiency of the work process. It is also noted that temperature affects cutting resistance forces significantly less in asphalt concrete containing high amount of gravel.

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Stresses in soil are a link between all parameters and operation modes of a vibratory roller and deformations at different depths of the soil. The paper presents a research technology and the results of measuring stress amplitudes in soil at depths of 0.15, 0.3, and 0.5 m at different dynamic moduli of soil deformation Evd. It is established that in the surface layer (0.15 m deep) within a single loading cycle, the duration of stress buildup phase is 1.5…2 times lower than the duration of stress relief phase, and this ratio increases with compaction. Within one roller pass in the surface layer (0.15 m deep), the increase period of the amplitudes of separate stress cycles is 1.2…2 times longer than the decrease period of those, and this ratio also increases with compaction. It is established that the vibration impact of a roller, similarly to the impact loading of soil with a tamper, affects how the stresses change during the relief phase at each impact cycle. This change is the same as how the stresses change during the relief phase in a surface layer (0.15 m deep), which confirms that it is possible to apply the provisions of the dynamic theory of plasticity not only for impact, but also vibratory and vibro-impact soil compaction modes. The obtained results can be used to update and verify the existing and future mathematical models of soil compaction with vibratory rollers.

Introduction. The article is devoted to the research results on cutting resistance of a road asphalt concrete in the process of the removal of worn coatings by the working elements of milling machines. The relevance of the work is due to the occurring of new brands of asphalt concrete alongside with the use of new types of cutting elements, for which it is difficult to predict the load on the working element when solving the problems of designing new ones and substantiation the operating conditions of the current machines. The purpose. The objective of the study of the interaction of a single cutting element of a road mill with a material at the best fit of speed and geometric parameters of a cutting process with real machines is solved.Materials and methods. The experimental work was carried out by determining the tangential component of a cutting resistance strength, as well as the work of this strength on a pendulum desk using a unit recording equipment. Four different types of asphalt concrete were being destroyed. A two-factor experiment was conducted for each type of the material. The tangential components of a cutting resistance strength depending on the thickness of the cut chips and the temperature of the material were evaluated.Results. As a result of the experiment, the data were obtained that make it possible to reasonably determine the loads on the teeth of road milling machines, to determine a power capacity of the process and the drive power of the working element. It was found that the growth of the tangential component to a cutting resistance strength occurs quite intensively alongside with an increase in the thickness of the cut chips, only at the initial stages of the penetration of the cutter. With an increase in the thickness of the cut chips, the growth of the tangential component to a cutting resistance strength does not occur so intensively. In all cases the temperature of the material has an impact on the value of a cutting resistance strength, but this effect is less significant for asphalt concrete with a higher crushed stone content.Discussion and conclusion. The obtained data make it possible not only to determine the tangential strength to cutting resistance on the cutting elements of the working element of the milling machine, but also to find rational ways to place the cutting elements on the working element, as well as to determine the rational operation conditions of the current and new machines. This is possible when using the results in a mathematical model that describes the operation of the milling working element as a whole.Financial transparency: the authors have no financial interest in the presented materials or methods. There is no conflict of interest.

Introduction. The article is devoted to the results of a study of the cutting resistance of road asphalt concrete in the process of removing worn coatings by the working bodies of milling machines. The relevance of the work is due to the emergence of new grades of asphalt concrete and new types of cutting elements, for which it is difficult to predict the loads on the working body when solving the problems of designing new and justifying the operating modes of existing machines.Purpose. To calculate the parameters of the working body of the road milling machine.Materials and methods. The experimental work was carried out by determining the horizontal and vertical components of the resistance force of cutting asphalt concrete. The research was carried out on a mechanical stand with a movable plate, using recording equipment. Four different grades of asphalt concrete were destroyed. A twofactor experiment was conducted for each brand of material. The horizontal and vertical components of the cutting resistance forces were determined depending on the chip cross-sectional area, the grade of asphalt concrete and the type of cutting element.Results. As a result of the experiment, data were obtained that make it possible to reasonably determine the loads on the working body of the road milling machine. It is proved that the dependence of the cutting resistance forces on the chip cross-sectional area of the cutting element has a nonlinear character. The data obtained allow to comprehensively answer questions concerning the justification of the parameters of road milling machines.Discussion and conclusion. The obtained data allow to develop a mathematical model of the asphalt concrete milling process which will make possible to determine not only the loads on the working body and the energy intensity of the process, but also to reasonably approach the placement of cutting elements on the drum, determine the rational range of equipment operating modes and solve the problems of choosing operating modes depending on the type of asphalt concrete.