Vol 46, No 5 (2017)

The aspects of choosing the design parameters of a vibrating machine made according to the scheme of a series two-mass vibrating system, as well as of the modes of its oscillations excited by two synchronously rotating unbalanced vibration exciters with a drive of limited power, are considered. The limitations on possible modes of oscillation excitation caused by taking the designed features of the vibration exciter into account are determined. At the specified masses and stiffnesses of a vibrating system, as well as for the specified parameters of oscillations of the actuating element, the rational values of the parameters of vibration exciter and the damping in the components of the vibrating system and dynamic modes, which are characterized by low expenditures of energy and a small dynamic effort transmitted to the foundation of the machine, are determined. The oscillation modes in which changing the mass of the actuating element leads to the smallest changes of the amplitudes of its oscillations are determined.

From preset pressure values on both surfaces of a plate, its bending is determined depending not only on the pressure difference but also on the product of the average pressure and the curvature of the middle surface. The latter component of this action is determined according to the models of Kirchhoff and Timoshenko for the case of a cylindrical linear bending of a plate. It is shown that taking into account the average pressure leads to an increase in the effective flexural rigidity. The value of deflection according to the models of Kirchhoff and Timoshenko is compared with a classical result. A criterion is established for the situation where the influence of the ambient pressure on the plate bending can be significant. The effect of the average pressure exerted on the longitudinal stability of the plates is determined.

The article deals with a complex application for the structural synthesis and parametric optimization of the design of transportation and technological systems and evaluation of innovative engineering solutions based on advanced morphological approach. The approach is based on the multicriterion principles, cluster analysis, and the theory of sets. The article provides examples of application of the proposed approach to the selection of the process of manufacturing of long hollow shafts of gas turbine engines from heat-resistant alloys and steels under isothermal conditions, determination of the optimal values of the resonant transducer for reducing longitudinal vibrations of a mechanical system, and synthesis of transportation systems. The application of the advanced morphological approach enables the refining and ordering of the structuring of the problems to be solved. The degree of the validity of the adopted solution is considerably increased by applying to every variant of the selected structure the method of parametric optimization of the LPS search implemented by a separate algorithm, which enables enhancement of the quality (technological level) of the technical systems under design.

Mechanical structures have been developed for defining strength coefficients, which confirm the specified reliability requirements and have been referred to as safety coefficients. Safety coefficients have been utilized in the theoretical and experimental development of structures. These coefficients are the products of several particular coefficients found by probabilistic and statistical procedures, namely, the average strength coefficient for meeting the reliability requirements, the relation of the average mechanical tension of the material to the tension guaranteed by GOST, the coefficient for the test plan and the incompleteness of the test results, the coefficient for the difference between the dynamic response coefficients in dummy blocks and mechanical structures, the coefficient for the replacement of multiple loading by single loading, etc. Safety coefficients have been utilized during independent and dependent tests.

Forecasting of the residual life of machine and structure elements requires consideration of the changes of the metal condition until it achieves its critical states. The failure of the KAMAZ truck spring during the cold operation period under the climatic and natural conditions of the North was studied taking the metal degradation in the zones of different loading into account. The structural damage was estimated using the microhardness and porosity parameters. The physical mechanisms that change the microhardness and the formation of the pore system in the spring steel were analyzed. It is shown that a deviation of the value of the metal microhardness from the normal distribution law is observed in the zone of development of a fatigue crack in the spring. Satisfactory resistance of the spring material to the development of a failure is revealed under the considered temperature–load conditions. A materials-engineering analysis confirmed the role of the road conditions as a more significant destructive factor during the working of the spring in the permafrost zone compared to the factor of the low temperatures.

An enzymatic-cavitation method for the biological treatment of organic-containing wastewater and sludge treatment has been developed, according to which the air supply is carried out not by compressors, but rather ejectors. In addition, low-intensity cavitation is provided. The biological treatment of the wastewater has been performed at a temperature of 10–42°C. The energy consumption of the process is reduced by six times, while the time of sludge treatment is 8–10 h at a pressure of 0.30–0.35 MPa. The treated sludge has some adsorptive properties.