Energy State of a Plastically Deformed Surface Layer

AbstractThe paper reports the results of experimental research on the substantiation of the criterion for steel strengthening effectiveness established on a basis of an energetic approach to the consideration of the mechanism for the surface layer formation with dynamic methods of plastic forming. Using the analogy between the processes of energy absorption of the crystal lattice under mechanical loading and under heating, the work demonstrates that the maximum specific energy which can absorb the crystal lattice corresponds to the value equal to the difference between the heat content (enthalpy) of the material in the solid state, at the melting temperature and enthalpy H_TS at 2930К. The proposed method and experimental device allowing to estimate the stored energy in the plastically deformed surface layer as the difference between the work expended in plastic deformation of the material and the quantity of the released heat. It was established that the energy growth limit in the local plastically deformed volume of a surface occurs at making of 11-13 acts of the action force; the further increase in acts influences the energy state of the surface as it becomes stabilized

К решению задачи синтеза системы управления процессом дозированной подачи электродной проволоки для оборудования дуговой сварки

Goal. Refinement of the methodology for the development of an effective control system for an electric drive with controlled relay-type regulators for organizing a metered feed of an electrode wire using the parameters of the arc process with the possibility of using it in design practice and practice of technological application. Methodology. The proposed method for the mathematical description (mathematical model) of the system of the developed structure electric drive - arc process with current feedback of welding with a variable structure device is based on the theory of automatic control as applied to nonlinear elements, the application of the theory of operational calculus. At the same time, a selection and description of a nonlinear node in the feedback circuit in the form of a relay element with a certain structure and subsequent linearization of this element was made. As an electric motor of the electrode wire feeder, a new development of a specialized valve electric motor is used, which is used in the system with a microprocessor controller. Results. Due to the presence of a substantially nonlinear link, the calculation of the valve electric drive system – the arc process can be found on the basis of a system of nonlinear differential equations, which is practically impossible for practical application. In this work, these complications are overcome on the basis of a rational choice of the description of the nonlinear link, its harmonic linearization and obtaining on this basis a mathematical description of the system, from which, using the methodology of operational calculus, the relations necessary for calculating the parameters of the system are determined in analytical form. Originality. The problem of calculating a rather complex problem of mathematical description of the valve electric drive system – a technological link in the form of an arc process with a substantially nonlinear link in the feedback circuit in the work is solved with the effective use of a set of methodological methods, which include as a means of representing individual links, including nonlinear links selected simplifications and solutions of the obtained differential equations using original methods of operational calculus. The proposed method (mathematical model) is tested in two directions – oscillography of a real system, as well as system simulation. Practical significance. Using the developed methods for describing the control system, it is possible to calculate its characteristics and, on their basis, select the parameters for setting the electric drive controller, which allows, without additional experimental research, to obtain the necessary character of the transfer of electrode metal, and, consequently, the quality of the result of the arc process.Проанализированы существующие системы активного влияния на перенос электродного металла при управлении процессом электродуговой сварки плавящимся электродом, в том числе, и на основе импульсной подачи электродной проволоки. Особо выделен новый способ сварки – с управляемыми параметрами движения за счёт введения в электропривод обратных связей по параметрам дугового процесса cвврки-наплавки с дозированной подачей проволоки. Рассмотрен алгоритм реализации сварки с дозированной подачей. Выбран электропривод механизма подачи, который базируется на специально разработанном быстродействующем вентильном электродвигателе с компьютеризованным регулированием. Для анализа и выбора параметров этой системы предложено рассматривать её в комплексе с дуговым процессом с применением методов гармонической линеаризации

К решению задачи синтеза системы управления процессом дозированной подачи электродной проволоки для оборудования дуговой сварки

Goal. Refinement of the methodology for the development of an effective control system for an electric drive with controlled relay-type regulators for organizing a metered feed of an electrode wire using the parameters of the arc process with the possibility of using it in design practice and practice of technological application. Methodology. The proposed method for the mathematical description (mathematical model) of the system of the developed structure electric drive - arc process with current feedback of welding with a variable structure device is based on the theory of automatic control as applied to nonlinear elements, the application of the theory of operational calculus. At the same time, a selection and description of a nonlinear node in the feedback circuit in the form of a relay element with a certain structure and subsequent linearization of this element was made. As an electric motor of the electrode wire feeder, a new development of a specialized valve electric motor is used, which is used in the system with a microprocessor controller. Results. Due to the presence of a substantially nonlinear link, the calculation of the valve electric drive system – the arc process can be found on the basis of a system of nonlinear differential equations, which is practically impossible for practical application. In this work, these complications are overcome on the basis of a rational choice of the description of the nonlinear link, its harmonic linearization and obtaining on this basis a mathematical description of the system, from which, using the methodology of operational calculus, the relations necessary for calculating the parameters of the system are determined in analytical form. Originality. The problem of calculating a rather complex problem of mathematical description of the valve electric drive system – a technological link in the form of an arc process with a substantially nonlinear link in the feedback circuit in the work is solved with the effective use of a set of methodological methods, which include as a means of representing individual links, including nonlinear links selected simplifications and solutions of the obtained differential equations using original methods of operational calculus. The proposed method (mathematical model) is tested in two directions – oscillography of a real system, as well as system simulation. Practical significance. Using the developed methods for describing the control system, it is possible to calculate its characteristics and, on their basis, select the parameters for setting the electric drive controller, which allows, without additional experimental research, to obtain the necessary character of the transfer of electrode metal, and, consequently, the quality of the result of the arc process.Проанализированы существующие системы активного влияния на перенос электродного металла при управлении процессом электродуговой сварки плавящимся электродом, в том числе, и на основе импульсной подачи электродной проволоки. Особо выделен новый способ сварки – с управляемыми параметрами движения за счёт введения в электропривод обратных связей по параметрам дугового процесса cвврки-наплавки с дозированной подачей проволоки. Рассмотрен алгоритм реализации сварки с дозированной подачей. Выбран электропривод механизма подачи, который базируется на специально разработанном быстродействующем вентильном электродвигателе с компьютеризованным регулированием. Для анализа и выбора параметров этой системы предложено рассматривать её в комплексе с дуговым процессом с применением методов гармонической линеаризации

The hypothesis of formation of the structure of surfaced metal at the surfacing based on the application of the prognostic algorithm of control the electrode wire speed

The growth of a drop in the process of surfacing by a consumable electrode is characterized by a linear dependence of the current change on time. A hypothesis has been put forward, according to which a reduction in the feed rate of the electrode wire to zero in this time interval will substantially reduce the spraying loss and improve the formation of the surfacing roller. For the implementation of which, the use of regulators with a typical law of regulation is proposed, but not according to the current value of the arc current, but according to the forecast. A key feature of these researches is a realization given surfacing process with the imposition of external mechanical oscillations with specified amplitude-frequency characteristics on the welding bath. Analytical calculation of the transfer function for the prognostic PID regulator with the simplest linear prediction taking into account the oscillation of the weld pool is given

Simulation of Beam-Beam Effects and Tevatron Experience

Effects of electromagnetic interactions of colliding bunches in the Tevatron had a variety of manifestations in beam dynamics presenting vast opportunities for development of simulation models and tools. In this paper the computer code for simulation of weak-strong beam-beam effects in hadron colliders is described. We report the collider operational experience relevant to beam-beam interactions, explain major effects limiting the collider performance and compare results of observations and measurements with simulations.Comment: 23 pages, 17 figure

Extraction of Kaon Formfactors from K^- -> mu^- nu_mu gamma Decay at ISTRA+ Setup

The radiative decay K->mu nu gamma has been studied at ISTRA+ setup in a new kinematical region. About 22K events of K^- -> mu^- nu_mu gamma have been observed. The sign and value of Fv-Fa have been measured for the first time. The result is Fv-Fa=0.21(4)(4).Comment: 11 pages, 21 figures, submitted to Phys. Lett.

Search for Heavy Neutrino in K->mu nu_h(nu_h-> nu gamma) Decay at ISTRA+ Setup

Heavy neutrino nu_h with m_h < 300MeV/c^2 can be effectively searched for in kaon decays. We put upper limits on mixing matrix element |U_mu_h}|^2 for radiatively decaying nu_h from K->mu nu_h (nu_h -> nu gamma) decay chain in the following parameter region: 30MeV/c^2 < m_h < 80MeV/c^2; 10^{-11}sec < tau_h < 10^{-9}sec. For the whole region |U_{mu h}|^2 < 5 x 10^{-5} for Majorana type of nu_h and | U_{\mu h}|^2 < 8 x 10^{-5} for the Dirac case.Comment: Published in Phys. Lett.

Temperature Effect on the Stability of the Polarized State Created by Local Electric Fields in Strontium Barium Niobate Single Crystals

The stability of ferroelectric domain patterns at the nanoscale has been a topic of much interest for many years. We investigated the relaxation of the polarized state created by application of a local electric field using a conductive tip of a scanning probe microscope for the model uniaxial relaxor system SrxBa1−xNb2O6 (SBN) in its pure and Ce-doped form. The temporal relaxation of the induced PFM contrast was measured at various temperatures. The average value of the induced contrast decreases during heating for all investigated crystals. Below the freezing temperature the induced state remains stable after an initial relaxation. Above the freezing temperature the induced state is unstable and gradually decays with time. The stability of the induced state is strongly affected by the measuring conditions, so continuous scanning results in a faster decay of the poled domain. The obtained effects are attributed to a decrease of the induced polarization and backswitching of the polarized area under the action of the depolarization field