SCIENCE & EDUCATION

The authors present a model for calculation of a spherical aerostatic bearing with porous boost limiters based on the Reynolds equation of gas lubrication with all fixed summands. The problem is solved in the program Comsol 3.5a by the finite element method. The state of the spindle was determined by the displacement vector, translational and angular velocity. Pressure distribution, support forces and moments, as well as air flow are also calculated. The presented model is used to estimate simplified solutions obtained under different assumptions at designing precision spindles.

The article presents assessment of damping properties of magnetorheological (MR) elastomers under their exposure to a magnetic field. The authors study the efficiency of vibration energy absorption by MR elastomers with the use of the obtained dependences of mechanical hysteresis. The results of experimental studies of the active damper are based on the MR elastomer.

The aim is to develop a design procedure, creation and study of characteristics of a high-precision wide-range airflow meter - a meter of small linear and angular movements which is built on the basis of an adjustable “flapper-nozzle” orifice. For reading service-differential and power characteristics of the flowmeter a compressor-batcher was used, it provided a stable and deterministic mass flow rate of compressed air. The prototype was a wide-range flowmeter, its experimental characteristics were received. The method of calculation and the experimental data can be used to make pneumatic automation devices.

As a rule, damping and absorbing properties of materials and structures are determined, basing on the German-French version of terminology. Absorbing properties of porous materials and honeycomb structures can be quantified by energy density shock absorption and energy efficient impact absorption based on the diagram of deformation of porous materials and honeycomb structures. These estimates of single (one-time) shock absorbers are similar to the impact energy received by the absorber, and to efficient energy shock absorption used in the evaluation of multiple shock absorbers. However, in the automobile industry damper is called shock absorber (using the Latin version of the word "depreciation"), and in the field of explosive and impact loading of structures shock absorber is called damper. Taking into account this fact will allow to avoid confusion in the domestic scientific and technical literature.

Application of the Taylor test (cylinder) allowed to obtain experimental data on dynamic behavior of volume-perforated samples of the aluminum alloy D16T at an impact velocity against a hard wall of up to 150 m/s. To calculate the impact, software packages LS-DYNA and ANSYS AUTODIN in two versions were used. The first variant included direct modeling of the structure of volume-perforated samples by the finite element method, and the second variant included using constitutive equations of porous elastoplastic medium based on a homogeneous model. For the second calculation variant the authors applied both experimental data in the form of a deformation curve obtained for uniaxial stress state and calculation data based on numerical simulation of deformation and compression of volume-perforated samples. The authors received a good qualitative agreement between the calculated and experimental data in the Taylor test, as well as a satisfactory quantitative agreement between the calculated and experimental results.

 In order to move objects with submicron accuracy and vibration control of equipment, in modern precision equipment precision positioning mechanisms based on magnetorheological fluids (MRF) can be successfully applied. It is shown that the work of these mechanisms have a significant impact on the properties of the fluid and, in particular, on electrical resistance and the bulk modulus of elasticity. It was found that with application of an external field to MRF electrical resistance decreases by 30% and the bulk modulus increases by 18%.

The authors present results of experimental evaluation of ability of surface layers of nitride steels and alloys to resist damage under conditions of deformation during friction. A new approach to comparative evaluation and selection of nitriding mode of parts and friction joints is proposed.

The authors carried out experimental studies aimed at development of variants of systems of continuous electric communication with the accelerometer under the conditions of application of terminal ballistics accelerometry (TBA-technology) to impact of a rigid body at an angle to the surface of the medium under test. A particular case of TBA-technology was tested under laboratory conditions for the case of inclined impact of soil medium along with defending screens. The algorithm of retrieving data on dynamic mechanical properties of soil medium using registrations of deceleration history of a rigid projectile during the penetration process into the medium under test was debugged. The developed technology is suitable for obtaining data on dynamic mechanical properties of soil medium in the range of sub-sound impact velocities.

The article considers comparison of coating properties made of tool steel R6M5, created by means of gas-powder cladding with pulse and continuous laser emission. The renewal of cutting tools and equipment at machine-building factories is an urgent problem of production modernization and reduction of its costs. The laser gas-powder cladding technology allows to simplify the process of renewing and to make it local and precise. The authors investigate microstructure, microhardness, porosity and wear resistance of coatings made with pulse and continuous laser emission.

In this article the authors consider properties of Cr17Ni13Mo2Ti and 40Cr13 coatings made by coaxial gas-powder laser cladding. CW fiber laser emission was used to create such coatings. Operating characteristics of coatings made by laser cladding of these steels are currently byways of learning. Usage of powder as a filler material is economically advantageous because it allows to produce coatings with different chemical compositions and properties. Besides, in comparison with the wire filler, uniform mapping of powder alloys onto difficult trajectories is easier. The article covers investigation of coating structure and mechanical properties along with establishment of their applicability domains in order to meet the demands of modern machine building.

It was shown in the article that any technological process can be considered as an energy conversion device. Each method, approach, means of treatment has a single-piece tool which is external energy. Performance factors are formed at the expense of both transformation and numeric distribution of external heat and maintenance of energy run-off conditions. The required output parameters of the forming process are achieved by controlling the internal processes and effects occurring in the work zone.

 The aim of this work is to research bursting strength of mineral-based oil designed to be used as a working liquid for hydraulic drives. Experimental setup on the basis of the mechanism consisting of a pneumatic-drive (pneumatic cylinder) and a vacuum pump (hydraulic cylinder) united by a common arm was created. The author proposes methods of hydrodynamic and burst vacuum extraction for removal of dissolved and undissolved air from the liquid. Quantitative estimation of bursting strength of mineral oil and the influence of degassing depth on it was given.

 Dependence of material cutability on specific work of inelastic deformation until destruction was obtained experimentally. It was shown that technological and technical economical characteristics of cutting were energetic characteristics. Application of energetic characteristic of cutability was demonstrated by the example of efficiency estimation of the combined machining method – that is, cutting with outrunning inelastic deformation (OID) for which known cutability criteria are unacceptable.

The article refers to the common question of project process multi-variance that can be used in efficient problem solving. The authors consider one of the approaches to multi-variant project solution generation during the development of technological processes of machine processing at the phase of creating the functional structure and operational instruments. It was shown that methodology of the decision-making theory can be used as a means of formally informed choice of the preferred alternative from a set of generated solutions.

The author proves the urgency of designing production facilities for multiproduct manufacturing and describes a methodological approach to calculation of the required number of equipment subject to time consumption in alignment procedures and rejection of replenishing. The analysis of NC machinery functional status is presented. The author proposes hypotheses of machining time per detail dependence on refining time and age related realignment. The results can be used for designing production facilities and planning manufacturing programs for NC machinery facilities.

 The article covers the data on actual functionality of NC machines as part of multiproduct manufacturing facilities; the data is based on the author's production research. The main categories of fund consumption were analyzed. The main problems of introducing up-to-date high-performance NC machines at domestic machine building plants were considered. The results and recommendations presented in the article can be used to solve design problems or for technical re-equipment and upgrading machining process.

The authors determine organizational and technological factors influencing productivity of technological systems based on processing-assembly concentration. The authors analyzed these factors and presented a mathematical model showing savings on time for manufacturing on the basis of processing-assembly concentration.

The article covers an urgent methodological approach to solving the problem of determination of the number of assembly sets of details and batch sizes in order to provide continuous mechanical assembly production with minimal costs. Non productive time consumption for machinery manufacturing facilities invariant to their production lines were taken into account in calculating the optimum number of assembly sets. The author provides an example of calculating an optimum number of serially produced assembly sets for multiproduct manufacturing. The proposed technique was aimed at solving design and planning problems of mechanical assembly production.

The author proposes standard solutions for choosing a rational technology of dimensional processing of constructions made of composite materials – these solutions are based on researches conducted at BMSTU and on their practical application. It was shown that development of new processing techniques and special equipment, purposeful creation of the required energetic state of work material, application of combined energy deposition are promising directions to improvement of the cutting process which ensure high quality and economical performance of the product at the stage of dimensional processing.

The authors propose a generalized structural diagram of technological renovation processes of machine elements, based on the characteristic of transformation vicissitude of entry shell properties. The authors show the ways to provide the quality of renewable products, basing on the analysis of interrelation between the structural diagram elements, considering technological inheritance of renewable product properties. The concept “the inheritance of life cycle” was introduced and described.