Establishing the technical performance of the chain excavator with cutters working in conditions critical deep cutting of soils

The calculated dependence for determination of technical productivity of the chain excavator with the cutters working in the conditions of critical depth cutting of soils is offered. An assessment is given for the practical implementation of the research results.

Partial-cluster model of viscosity of copper-aluminum melt

The adequacy of the developed partial-cluster viscosity model with respect to melts of metal alloys was verified using the well-studied copper-aluminum system, for which the state diagram and viscosity isotherms are known in a wide range of compositions. Based on the literature on the thermodynamics of mixing copper and aluminum melts, it was found that this shift is accompanied by heat generation due to the formation of intermetallic compounds in the melt. The destruction of these compounds requires appropriate heat consumption, therefore, it should be taken into account in the partial-cluster viscosity model as an additional thermal barrier to randomization. On this basis, a refined and more generalized form of the partial-cluster model with the expression of the randomization energy of the melt in the form of the algebraic sum of the randomization heat along the liquidus line and the heat of destruction of any intermetallic formations is proposed ΔHch = RTliq – ΔHmix. Application of the generalized partial-cluster model to copper-aluminum melts ensured the repetition of the extreme form of empirical isotherms, even with the appearance of excess viscosity in the calculated dependence. A more detailed analysis of the heat of mixing according to its covalent and metal components showed that the second of them is already randomized and only the covalent component should be taken into account, which should be randomized and should be included in the total randomization barrier in the form ΔHch = RTliq – ΔcovH. Taking this component into account allowed us to obtain a more adequate calculated dependence of the viscosity of the Cu – Al alloy at a temperature of 1100 оC with a correlation coefficient of 0.986, which can be considered as a priority result in the description of viscosity isotherms according to state diagrams. This result is due to the analytical determination of the fraction of clusters in the melt based on the distribution of clusters proposed by the authors according to the number of particles included in the framework of the concept of randomized particles developed by the authors, which is directly related to the Boltzmann’s distribution.

STUDY OF THE KINETICS OF DRYING IRON (II) SULFATE HEPTAHYDRATE BY FILTRATION METHOD

The object of research: kinetics of filtration drying process of iron (II) sulfate heptahydrate. Solved problem: to obtain the calculated dependence of the kinetics of filtration drying, which predicts the nature of the change in the moisture content of the material in time during the period of complete saturation of the thermal agent with moisture in the range of heights of the material layer 30.10-3–120.10-3 m and the speeds of the thermal agent 0.46–1.61 m/s. Main scientific results: The kinetics of filtration drying of iron (II) sulfate heptahydrate was investigated at different heights of the material layer and pressure drops over dry material, which means at different speeds of movement of the thermal agent. A certain critical moisture content, which is Wcr=0.065 kg H2O/kg dry mat and the time it reaches at different heights of the material layer and the speeds of movement of the thermal agent. Based on the solution of the system of differential equations of material balance in the layer and the kinetics of drying, the kinetic coefficients for iron (II) sulfate heptahydrate a=15.75 1/m, α=3.03.10-3 1/s were determined, which made it possible to obtain the calculated dependence of the kinetics drying, which predicts the nature of the change in the moisture content of the material over time during the period of complete saturation of the thermal agent with moisture in the range of heights of the material layer H=30.10-3–120.10-3 m and the velocities of the thermal agent υ=0.46–1.61 m/s. The area of practical application of the results: enterprises for the production of titanium (IV) oxide with the production of iron (II) sulfate heptahydrate as a by-product and enterprises specializing in the manufacture of pigments based on iron (II) sulfate heptahydrate. Innovative technological product: iron (II) sulfate tetrahydrate (FeSO4•4H2O, rosenite), obtained as a result of drying by the filtration method. Scope of application of the innovative technological product: in the production technology of iron oxide pigments.

Динамика локализованной кольцевой нелинейной волны в углеродной нанотрубке

The propagation of nonlinear localized soliton-like super-acoustic longitudinal waves in a carbon nanotube was explored by the molecular dynamics modeling. Ring waves were excited by pulsed action on all the atoms of the edge zigzag layer and they got an initial velocity along the axis of the nanotube. It was shown that the velocity of a localized (soliton-like) ring super-acoustic wave increased with an increase in the initial velocity of the edge atoms. The calculated dependence of the propagating wave velocity on the initial velocity of the edge atoms was given.

Calculation of the frequency of own oscillations of polyurethane shock absorbers used in shipbuilding

В работе приведено обоснование необходимости применения амортизаторов и замены традиционного эластомерного материала резины на более совершенный материал – полиуретан. Целью работы является экспериментальное исследование деформативности полиуретанового виброизоляционного массива амортизатора и получение расчетной зависимости для определения собственной частоты колебаний системы «агрегат-амортизатор». В работе представлен подробный анализ зависимости коэффициента виброизоляции от соотношения частот вынужденных и свободных колебаний. Отмечено, что эффективность виброизоляции тем выше, чем больше это соотношение частот. Учитывая, что частота вынужденных колебаний - величина заданная, для повышения эффективности виброизоляции следует понижать частоту собственных колебаний амортизатора благодаря применению новых виброизоляционных материалов. В качестве эластомерного материала предложен полиуретан фирмы «Synair» (Великобритания) твердостью 40,45 и 50 ShA. Приведено описание нагружающего устройства для исследования деформативности виброизоляционного массива амортизатора серии КАС (корабельный амортизатор сварной). Получена эмпирическая зависимость коэффициента ужесточения в зависимости от коэффициента формы виброизоляционного массива амортизатора. Представлена эмпирическая зависимость по определению модуля упругости эластомерного материала виброизоляционного массива амортизатора в зависимости от условий контактирования на торцах и фактора формы массива. Представлена расчетная зависимость по определению частоты собственных колебаний амортизатора в зависимости от величины статической деформации. Представленная зависимость позволяет на стадии проектирования определить собственную частоту колебаний и предупредить возникновение такого опасного явления, как резонанс. The paper substantiates the need for the use of shock absorbers and the replacement of the traditional elastomeric rubber material with a more advanced material - polyurethane. The aim of the work is an experimental study of the deformability of a polyurethane vibration-isolating array of a shock absorber and obtaining a calculated dependence for determining the natural frequency of oscillations of the aggregate-shock absorber system. The paper presents a detailed analysis of the dependence of the vibration isolation coefficient on the ratio of the frequencies of forced and free vibrations. It is noted that the effectiveness of vibration isolation is higher, the greater the ratio of the frequencies of forced and natural vibrations. Taking into account the fact that the frequency of forced vibrations is a given value, to increase the efficiency of vibration isolation, it is necessary to reduce the frequency of natural vibrations of the shock absorber due to the use of new vibration insulation materials. The work describes the loading device for studying the deformability of the vibration-isolating array of the KAS series shock absorber (welded ship shock absorber). An empirical dependence of the tightening coefficient is obtained depending on the shape coefficient of the vibration-isolating array of the shock absorber. The paper presents a calculated dependence on determining the frequency of natural oscillations of the shock absorber depending on the magnitude of the static deformation.

Before Calculating the Teeth of Spur gears on the Bend

The aim of the work is to improve the calculations of spur cylindrical wheels per bend, due to the fact that the existing formulas do not give the actual value of the maximum stress, and the diagram does not correspond to the real law of stress distribution. In order to obtain satisfactory results, it is more correct to calculate the teeth at the maximum local stress. Combining the coefficients and substantiating the calculated dependence to determine the value of the coefficient of the shape of the tooth under load, applied at any point of the working profile of the tooth, to obtain formulas for the bending strength of the teeth of the gear and wheel. When calculating the bending teeth, the calculation is based on the stresses arising at the base of the tooth, under the load applied at the top of the tooth. Consider first the most common calculation scheme. Dangerous section of the tooth as seen from the plot of total stresses indicates that the maximum normal stress occurs on the non-working side of the tooth - the compression side, however, since fatigue cracks occur at the base of the tooth on the stretching side, the calculation is based on tensile stress on the working side. The hypothesis of non-curvature of flat sections is unfair for short beams of variable cross section, so the total diagram does not correspond to the real law of stress distribution. But at the base of the tooth near the transition curve is the place of stress concentration. The actual dangerous cross-section lies below the cross-section of the depression, this is confirmed by the fact that the fatigue cracks form an angle with the load curve close to straight, and the fracture of the tooth has a convex shape. In this case, it is more correct to calculate the teeth at the maximum local stress. Combining the coefficients obtained a calculated dependence to determine the value of the coefficient of the shape of the tooth under load, applied at any point of the working profile of the tooth. As a result of the study it was found that the coefficient of tooth shape decreases with increasing number of teeth. This result was expected because as the number of teeth increases, the angle between the teeth decreases, and neighboring teeth perceive part of the stress that occurs in the loaded tooth. The formulas for checking the bending strength of gear teeth and wheels are obtained. The above refinement calculations of the teeth on the bend reflect the beneficial effect of improving the accuracy of the manufacture of teeth.

Генерация высших гармоник при распространении предельно короткого оптического импульса в среде углеродных нанотрубок с нелинейным поглощением

The problem of the propagation of an extremely short optical pulse in a medium of carbon nanotubes with nonlinear absorption and amplification is considered. Nonlinear absorption is described phenomenologically based on published data. The mode in which the gain is higher than the linear absorption coefficient is considered. This mode is also described phenomenologically. The extremely short optical pulse is considered on the basis of Maxwell's equations, with a microscopically calculated dependence of the current on the pulse field. The possibility of efficient generation of higher harmonics that are not initially present in the pulse is shown.

Submersion of the system «anchor-tightrope» of longline

A hydrodynamic problem for the longline system «anchor-tightrope» in resting fluid is formulated and solved on base of the theory of dynamics for systems with variable mass. The system of initial differential equations is solved by means of numerical methods using the software designed in MathCad-14 environment; parameters of the «anchor-tightrope» system in the process of submersion are calculated. Dependence of the time and velocity of submersion on type of anchor is analyzed taking into account the hydrodynamic forces dependence on Reynolds number. Influence of inertia force is determined. Cited results for dependence of the submersion time for fishing gear elements on depth are overviewed.