SCIENCE & EDUCATION

The article presents analysis of hydraulic drive for auto wheels in terms of its energy efficiency. Three main control modes are described – by volumetric change of pump capacity per revolution and change of flow sections of common valve gap (with two types of pump regulators). The authors provide comparison of these modes and indicate areas of their efficient application.

The problem of trajectory safety ensuring for the dynamic controlled object (DCO) that moves on a plane in which circle forbidden zone exists is considered. Mathematical model of DCO motion is described. At first the case of static circle forbidden zone is considered for the formalization of the fly-around problem, intervals of non-safety courses of motion which form a zone of dangerous trajectories for the class of piecewise path segments of motion consisting of trajectory of sharp turn of the maximum curvature and linear path segment after it. Problem of evaluation of the zone of dangerous trajectories in the case of dynamic circle forbidden zone is considered on the basis of the obtained description. As a result iteration algorithm of the zone of dangerous trajectories evaluation is formed.

Loads on centrifugal pump details change when disbursements of liquid in the “pump – pipes” system change. Mathematical model of the system and calculations indicate possible increase of hydrodynamics forces in the double-entry pump. The results can be used in pump bearings design.

Computation of the phase change sequence during the incubation interval of oversaturated solid solution of Ni-Al alloy breakage      was carried out (93% Ni, 7% Al by weight). Quantity of conversion stages in the process of oversaturated solid solution breakage, atom’s superfluous chemical potential with every metastable phase equilibrium, mass content of precipitated phases, newly formed phases’ chemistry, gradient of Al atoms’ chemical potential between solution and nucleating phases could be determined with formed digram of non-equilibrium phase states.

This article deals with the discrete multistep method of assembly technology selection with finite number of selection options on each step. It’s suggested to generate the set of allowed selection options automatically with the usage of oriented hypergraphs. The hypergraph is defined with the set of vertices – parts to be assembled, and the set of edges – assembly operations. The proposed method is based on the system of constraints on allowed assembly variants in the form of oriented hypergraph, introduced by a developer, followed by generating of the full solutions set, with these constraints taken in the account.

In this article the mathematical model of shrinkage defect in  nickel superalloys was introduced. Several important models dendritic skeleton permeability of two-phase zone were considered. The output of original permeability coefficient model was shown. This model takes in account the influence of casting microstructure on the nature of processes in two-phase zone. The simulation of quasi-stationary directed crystallization of nickel superalloy was carried out. The results of this simulation are in good qualitative and quantitative correlation with known experimental data.

In this article the imitating models of hydropressed conical pressure coupling were developed. The constructive and technological features of the coupling were taken in the account. Conditions of oil layer forming in the coupling both for static and dynamic processes were defined. The results of numeric experiment for static process are included. The algorithm for dynamic numeric experiment is described. An application domain of the imitating models is defined. Effectiveness of the imitating model usage is shown.