Purpose is mathematical modeling of fracturing as well as influence of gaseous products of explosive detonation on the changes in rock strength. Methods. Mathematical model, using foundations of Griffith theory, has been developed. To explain conditions of bridge formation while exploding lead azide charges, a two-stage description of solid particle condensation at a crack surface and inside it has been applied using the smoothed particle hydrodynamics. The analysis, involved electronic microscope, has helped verified the results experimentally. Findings. The effect of rock mass disturbance, resulting from explosive destruction, is manifested maximally right after the action. Subsequently, it decreases owing to the gradual relaxation of the formed defects. Therefore, an urgent problem is to develop ways slowing down strength restore of the blasted rock mass fragments. The process of rock fragment strength restoring may be prevented by microparticles getting into the microcrack cavities together with the detonation products. The research simulates their action. The data correlate to the simulation results confirming potential influence of the blasted rock on the dynamics of changes in the strength characteristics of the rock mass. Various compositions of charges with shells made of inert solid additions have been applied which solid particles can avoid the process of microcrack closure. Originality. For the first time, the possibility of deposition formation within rock micro- and macrocracks has been proposed and supported mathematically. Practical implications. Strength properties of the finished product and the energy consumption during impulse loading as well as subsequent mechanical processing of nonmetallic building materials depend on the strength properties of rock mass fragments. Hence, the ability to control the strength restore has a great practical value. Moreover, it can be implemented during the blasting operations.

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Purpose. Investigate and propose new possibilities of using 3D-printing technologies in designing and manufacturing mechanism of energy recovery with pneumatic motor. Methodology. We have applied the experimental simulation of pneumatic motor, it’s construction and work. Energy recovery mechanism was simulated and it’s parts was created using 3d technology. Results. The existing technologies of 3D printing, types and structure of 3D printers for design and manufacture of special equipment for the energy recovery mechanism with a pneumatic motor are analyzed and considered in detail. The main materials for printing are considered, as well as carbon-containing materials for FDM printing, their properties and characteristics are considered in detail. The kinematic analysis of the printer mechanism for delta type 3D printing is carried out, the positioning errors for this mechanism type are determined. Measurement of the obtained part and processing of statistical data were carried out. The obtained holes of the part are compared with the given nominal values, and the absolute error for the outer and inner diameters is calculated. Originality. For the first time, the roughness of the delta robot rods was calculated, and the structure stress state under the applied forces action was calculated. Practical value. Having analyzed all the above information on the 3D printing using possibility in the special equipment manufacture and parts of the energy recovery mechanism with a pneumatic motor, it is possible to conclude that the special materials and the latest technologies use can reduce the recuperator weight with the required structural elements strength. The information and results obtained in this study actually correlate with similar researches. In addition, they also have a necessary and sufficient basis in order to conduct research on the use of 3D technology for the manufacture of parts and components. References 16, table 1, figures 14.

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