No 3 (2023)

A mathematical model of a heavy-duty track modular unit, in which the mechanical suspension damper is a topologically optimized elastic frame with superelastic reinforcing elements made of a composite material with thermoelastic martensitic transformations, is proposed. The model is used to evaluate the internal force factors arising at the points of contact between the track rollers and the support platform. The model allows taking into account the influence of the dynamic load from the inertia of the nodes and parts of the mechanism. This model can be used to analyze the impact of the failure of the track rollers of tracked vehicles on the redistribution of forces between the remaining serviceable rollers. Based on the results of loading simulation, dependencies are obtained that make it possible to judge the level of loading of the support wheels in two operation modes; recommendations are given for further refinement of the model.

This article discusses the so-called gear train with adapted properties. Such gear trains are used to increase the load capacity of gear coupling by decreasing the maximum contact stresses by means of an increase in teeth contact compliance operating under skewed conditions. An approach has been proposed, including an analytical solution to the problem on its basis, and the equations for determination of the maximum contact stresses of gear teeth with annular grooves have been obtained. The decrease in the contact stresses of teeth with adapted properties upon skewing has been estimated and compared with those of regular teeth.

The problem of delayed fracture and long-term strength of multilayer composites represents not only fundamental but also applied interest. The proposed solution makes it possible to estimate the influence of the geometry, structure, and property ratio of the layered composite on its durability. The time to failure of a two-layer metal beam of rectangular cross section is determined as a function of the ratio of layer thicknesses and their Young’s moduli.

The method of molecular-dynamic modeling was applied for creating models of polyether ketone and two of its nanocomposites with fillers in the form of copper nanoparticles and with fullerene. The results of comparative study of the deformation-strength properties of these materials by means of uniaxial tension at a constant strain rate are presented. It was obtained that, when filling polyether ketone with fullerene, the elasticity value of the composite decreases by approximately two times, and in the case of filling of the same matrix with copper nanoparticles, its value increases by approximately 30%. At the same time, the average energy of intermolecular bonds of the composite with copper nanoparticles is 2.65 times greater than that of the composite with fullerene.

Scientific substantiation of the design and simulation techniques for one of the understudied aspects of oil supply, namely, jet supply of engine oil from the gaps of the rotating journal bearing to the “cylinder–piston” pairing of a high-speed four-stroke universal diesel engine, is given. The simulation resulted in visualization of the trajectory and zones of oil ingress on the friction surfaces of parts of the cylinder–piston group presented in this article, as well as a quantitative assessment of the oil volume in these zones and in the crankcase. The simulation technique and the results of its application can be of both scientific and practical interest for specialists in the field of lubrication design and reliability of piston machines.

This article discusses the possibility to produce hybrid workpieces from aluminum alloys AMg2, AMg5, and AMg6 using combined upsetting deformation with a surface shear (torsional upsetting). The finite element simulation of shape formation using the QForm 10.1.5 software has been applied. The obtained rheological models of deformed materials and the specially developed friction.sliding_velocity subroutine have allowed us to obtain simulation results agreeing well with the experimental data. Metallographic studies have confirmed the high joining quality of workpieces in the contact area.