Mapping Relation between Rail and Bridge Deformation Considering Nonlinear Contact of Interlayer

This paper examines the effect of structural deformation on the unit slab-type ballastless track structure of high-speed railway. The principle of stationary potential energy was used to map the relation between girder vertical deformation and rail deformation considering the effect of subgrade boundary conditions and the nonlinear contact of interlayer. The theoretical model was verified by comparing with the finite element analysis and experimental results. The theoretical model was used to analyze the effects of several key parameters on the rail deformation, such as vertical deformation amplitude, elastic modulus of the mortar layer, and vertical stiffness of the fasteners. The results show that the track slabs suffered significant disengagement, which makes the deformation of the track structure at the position of the beam joint tend to be gentle when nonlinear contact between the mortar layer and the track slabs was considered. The track slabs disengagement mainly occurs near the beam joints (the side of the deformed beam). As the deflection amplitude of the girder increases, the track deformation, the fastener forces and the disengagement length of the track slabs are obviously nonlinear. When the vertical stiffness of the fastener and/or the elastic modulus of the mortar layer increase, the fastener force and the track plate disengagement length increase monotonically and nonlinearly, which will adversely affect the life and safety of the track structure.

Using the galvanostatic pulse method to estimate the corrosion of reinforcement in structural elements

ABSTRACT Early steel bars corrosion in reinforced concrete elements is difficult to detect because of the lack of visible changes on the concrete surface. To assess reinforcement corrosion risk level without structure damage some non-destructive diagnostic methods are applied. One of them is the galvanostatic pulse method. This semi-non-destructive electrochemical method allows to determine the corrosion areas and estimate the steel bars corrosion activity. Using this method it is possible to measure some electrical parameters (corrosion current density, stationary potential and reinforcement concrete cover resistivity) that allow to indirectly estimate the reinforcement corrosion progress in concrete. So far this method has been generally applied to bridges. The article presents results of studies in which the galvanostatic pulse method was used to determine reinforcement corrosion risk in structures elements different than bridges. Two types of reinforced concrete columns were tested under different environment conditions and two groups of laboratory specimens which were subjected to freezing and thawing cycles in NaCl solution or stayed in natural air–dry conditions. The apparatus GP-5000 GalvaPulseTM was used. Based on the obtained results the conclusions were drawn. The galvanostatic pulse method allows to assess the progress of the reinforcement corrosion process in tested elements. However, it is necessary to measure simultaneously all parameters and make their complex analysis. RESUMEN La corrosión temprana de las barras de acero en elementos de hormigón armado es difícil de detectar debido a la falta de cambios visibles en la superficie del hormigón. Para evaluar el nivel de riesgo de corrosión de la armadura sin dañar la estructura se aplican algunos métodos de diagnóstico no destructivos. Uno de ellos es el método del pulso galvanostático. Este método electroquímico semi no destructivo permite determinar las áreas de corrosión y estimar la actividad de corrosión de las barras de acero. Utilizando este método es posible medir algunos parámetros eléctricos (densidad de corriente de corrosión, potencial estacionario y resistividad de la cubierta del hormigón de la armadura) que permiten estimar indirectamente el progreso de la corrosión de la armadura en el hormigón. Hasta ahora este método se ha aplicado generalmente a los puentes. El artículo presenta los resultados de estudios en los que se utilizó el método de impulsos galvanostáticos para determinar el riesgo de corrosión de las armaduras en elementos de estructuras diferentes a los puentes. Se ensayaron dos tipos de columnas de hormigón armado en diferentes condiciones ambientales y dos grupos de probetas de laboratorio que se sometieron a ciclos de congelación y descongelación en solución de NaCl o permanecieron en condiciones naturales de secado al aire. Se utilizó el aparato GP-5000 GalvaPulseTM. A partir de los resultados obtenidos se extrajeron las siguientes conclusiones El método de impulsos galvanostáticos permite evaluar el progreso del proceso de corrosión de la armadura en los elementos ensayados. Sin embargo, es necesario medir simultáneamente todos los parámetros y realizar su complejo análisis.

Evolution of Heavy Ion Beam Probing from the Origins to Study of Symmetric Structures in Fusion Plasmas

The overview discusses development of the unique fusion plasma diagnostics—Heavy Ion Beam Probing (HIBP) in application to toroidal magnetic plasma devices. The basis of the HIBP measurements of the plasma electric potential and processing of experimental data are considered. Diagnostic systems for probing plasma in tokamaks TM-4, TJ-1, TUMAN-3M and T-10, stellarators WEGA, TJ-II and Uragan-2M are presented. Promising results of the HIBP projects for various existing modern machines, such as TCV, TCABR, MAST, COMPASS, GLOBUS-M2, T-15 MD and W7-X and the international fusion tokamak reactor ITER are given. Results from two machines with similar size and plasma parameters, but with different types of the magnetic con-figuration: axisymmetric tokamak T-10 and helically symmetric stellarator TJ-II are compared. The results of studies of stationary potential profiles and oscillations in the form of quasimonochromatic and broadband fluctuations, turbulent particle flux, fluctuations of density and poloidal magnetic field are presented. The properties of symmetric structures—zonal flows and geodesic acoustic modes of plasma oscillations as well as Alfvén Eigenmodes excited by fast particles from neutral beam injection heating are described. General trends in the behavior of electric potential and turbulence in magnetized fusion plasmas are revealed.

Anodic behaviour of Zn0.5Al doped with molybdenum in acidic, neutral and alkaline media

The paper presents the results of a potentiodynamic study of the anodic behaviour of Zn0.5Al doped with molybdenum in the acidic (0.1 M, pH = 1; 0.01 M, pH = 2; 0.001 M, pH = 3), neutral (0.03, 0.3, 3%, pH = 7) and alkaline (0.001 M, pH = 10; 0.01 M, pH = 11; 0.1 M, pH = 12) media of HCl, NaCl and NaOH electrolytes. In the potentiodynamic mode with an electrode potential sweep rate of 2 mV/s, all Zn0.5Al-Mo samples containing from 0.01 to 1.0 wt% of molybdenum demonstrated a shift in the potentials of corrosion, pitting formation and repassivation. These potentials shift towards negative values in acidic and alkaline media, while shifting to positive values in a neutral medium. It was established that an increase in the concentration of electrolytes led to a shift of all the considered potentials towards negative values in all media - acidic, neutral and alkaline. This dependence is associated with the specific features of the process of anodic dissolution of alloys during the formation of an oxide film on their surface. The significance of the dependence of the stationary potential of free corrosion of alloys on time for establishing the passivity of surfaces in acidic, neutral and alkaline media was shown. It was determined that zinc alloys doped with molybdenum are resistant to pitting corrosion in all the investigated media. This resistivity is particularly high in acidic (0.001 M), neutral (0.03%) and alkaline (0.001 M) media of HCl, NaCl and NaOH electrolytes. The favourable effect of molybdenum on both the anodic behaviour of Zn0.5Al and the overall increase in the corrosion resistance of alloys was demonstrated. In comparison with undoped Zn0.5Al alloys, the corrosion rate of alloys doped with molybdenum (0.01-1.0 wt%) is 2-2.5 times lower. The proposed compositions of Zn0.5Al-Mo alloys can be used as noncorrosive coatings for steel products.

Study of the equilibrium free surface of a capillary liquid in a toroidal vessel

The paper considers an axisymmetric problem of determining the forms of equilibrium of liquid in spacecraft toroidal tanks under conditions close to weightlessness. In the absence of significant mass gravitational forces, the behavior of liquid fuel in tanks begins to be determined by surface tension forces, which are intermolecular forces at the interface of two phases. Relying on the principle of stationary potential, we obtained the conditions of equilibrium of the closed system "liquid - gas - solid wall" under microgravity conditions. The study introduces a system of differential equations that determines the form of equilibrium of a liquid in toroidal tanks, the Young — Dupre equation, the condition for the contact of a free surface with a solid wall, and the condition for the conservation of the volume of the liquid. Furthermore, we quantified the influence of various parameters, such as the contact angle α_0, the Bond number B_0, the ratio of the radii of the circles δ=R_0⁄r_0 and the relative filling volume of liquids V_0, on the form of the equilibrium of the capillary liquid. The study of the forms of equilibrium of liquid fuel makes it possible to develop recommendations for the design of intake devices for fuel tanks in rocket and space technology. Findings of research show that the obtained equilibrium surface is also the unperturbed boundary of the region occupied by liquid fuel, which gives necessary information for further investigation of the spacecraft dynamics.

Symmetry properties of a Brownian motor with a sawtooth potential perturbed by harmonic fluctuations

We present a study of general symmetry properties of a Brownian ratchet model. The study is based both on constructing chains of symmetry transformations reflecting explicit and hidden symmetries of the average ratchet velocity as a functional of the spatially periodic potential energy of a nanoparticle and on taking into account the symmetry types of periodic functions that are components of the potential energy of an additive-multiplicative form. A ratchet with a sawtooth stationary potential profile, dichotomously perturbed by a spatially harmonic signal, is investigated. Conclusions are made on both the possibility of occurrence of the ratchet effect and its direction for given values of the asymmetry parameter of the sawtooth profile, phase shifts of the control component, and frequencies of temporal fluctuations. These conclusions have been obtained only on the basis of symmetry transformations; that demonstrates the predictive value of the approach presented. The results of the symmetry analysis are confirmed by numerical simulation of the functioning of a ratchet with dichotomous stochastic spatially periodic fluctuations of the nanoparticle potential energy.

Increasing the corrosion resistance of carbon steel by means of dipinaconborate compounds

For the first time, the corrosion resistance of ST10 steel in a 3% NaCl solution in the presence of lithium dipynaconborates (DPBL), sodium (DPBN) and potassium (DPBK) was studied. The method of synthesis of these dipinaconborates is given and their physical and chemical characteristics are determined. Experiments on the measurement of stationary potential high resistance voltmeter potentiostat P-5848 shown that the introduction of dipingere lithium, sodium and potassium in 3% NaCl solution leads to a noticeable increase of the corrosion resistance of steel and pestiviruses action definecolor are in a row DPBC > DPPN > DPBL. According to the obtained data of anodic polarization in a 3% aqueous solution of NaCl, the steel is actively dissolved, and when 0.1 mol/l is added, THE steel passes into a passive state. The increase in the corrosion resistance of steel is explained by the formation of a dense passive ferrohydroxoborate film on the metal surface. Gravimetric studies with the determination of the average corrosion rate, braking coefficient and degree of protection of steel St. 10 in a 3% solution of NaCl with the addition of dipineaconborates of lithium, sodium and potassium of various concentrations found that the concentration of 0.5% is optimal for them. Fatigue and corrosion-fatigue tests of ST10 steel in a solution of sodium chloride without additives and with the addition of DPBK, DPBN, DPBL showed that dipinaconborates equally reduce the destructive effect of purely corrosive and corrosion-mechanical lesions. When the content of 0.5% of potassium dipineaconborate in a solution of sodium chloride, the cyclic strength of steel increases, which is associated with a decrease in the destructive factors in reducing the cyclic strength of steel under the effect of DPBK.

IMPROVEMENT OF PROTECTIVE PROPERTIES OF ANTI-CORROSIVE MASTIC

Целью исследований явилось совершенствование защитных свойств противокоррозионной мастики «Барьер» для обработки сельскохозяйственных машин и оборудования животноводческих комплексов. Объект исследования: олигомер Д-10ТМ, который добавляли в состав мастики «Барьер» в массовом соотношении 100:5 для улучшения ее противокоррозионных свойств. Для экспериментов использовали образцы из стали Ст3 размерами 100´25´2 мм. В качестве электролита служил 3 %-й раствор хлорида натрия. Защитную пленку на образцах получали методом окунания образцов в составы. Медленное (со скоростью 0,02-0,03 м/с) извлечение образцов обеспечивало одинаковую толщину пленки на всей их поверхности. Пленку на образцах высушивали при комнатной температуре (18-22 °С) в течение 24 ч. Исследование диффузионной стойкости пленок исследуемых составов в электролите показало, что введение олигомера Д-10 ТМ в состав мастики «Барьер» повышает сплошность покрытия почти на 30 %. Для электрохимических исследований противокоррозионных свойств составов образцы с покрытиями погружали в электролит и выдерживали в течение 24 часов. Значение стационарного потенциала образцов измеряли через каждые 4 часа с помощью потенциостата П-5848. Эффективность противокоррозионных свойств составов оценивали по смещению потенциала начала активации электрода в положительную сторону. Начальный электродный потенциал стали −0,44 В с защитным покрытием сразу смещается в более положительную сторону: с пленкой из мастики «Барьер» до −0,26 В, из полученной композиции – до −0,18 В. Причем активация металла начинается при положительном потенциале, равном +0,05…+0,075 В, т.е. интервал изменения потенциала от начального значения до начала активации составляет 0,49-0,525 В, что подтверждает высокие ингибиторные свойства полученной композиции. Следовательно, смесь мастики «Барьер» и олигомера Д-10ТМ может быть рекомендована в качестве композиции для защиты сельскохозяйственных машин и оборудования животноводческих комплексов от коррозионного разрушения. The aim of the research was to improve the protective properties of the anti-corrosion mastic “Barrier” for processing agricultural machinery and equipment of livestock complexes. Object of study: oligomer D-10TM, which was added to the composition of the "Barrier" mastic in a mass ratio of 100: 5 to improve its anticorrosion properties. For the experiments, we used samples of St3 steel with sizes 100´25´2. A 3% sodium chloride solution served as an electrolyte. A protective film on the samples was obtained by dipping the samples into the compositions. Slow (at a speed of 0.02-0.03 m/s) extraction of samples ensured the same film thickness over their entire surface. The film on the samples was dried at room temperature (18-22°C) for 24 hours. A study of the diffusion resistance of the films of the studied compositions in the electrolyte showed that the introduction of the oligomer D-10 TM in the composition of the "Barrier" mastic increases the coating continuity by almost 30%. For electrochemical studies of the anticorrosive properties of the compositions, coated samples were immersed in an electrolyte and held for 24 hours. The value of the stationary potential of the samples was measured every 4 hours using a P-5848 potentiostat. The effectiveness of the anticorrosive properties of the compositions was evaluated by the shift in the potential of the beginning of electrode activation in a positive direction. The initial electrode potential of steel with −0.44 V with a protective coating immediately shifts to a more positive side: with a film from mastic “Barrier” up to −0.26 V, from the resulting composition – up to −0.18 V. Moreover, metal activation begins at positive potential equal to +0.05 ... +0.075 V, i.e. the range of potential changes from the initial value to the start of activation is 0.49-0.525 V, which confirms the high inhibitory properties of the resulting composition. Consequently, a mixture of Barrier mastic and D-10TM oligomer can be recommended as a composition for protecting agricultural machinery and equipment of livestock complexes from corrosion damage.

INHIBITOR EFFICACY AND COMPOSITION OF OAK BAR EXTRACT

Regional and international researchers have proven that natural products, plants and their extracts can be used to reduce the corrosion rate. Such studies are relevant because natural inhibitors are obtained from renewable sources, therefore they are environmentally friendly. Ukrainian scientists have investigated the inhibition effect of oak bark extracts, but no such studies have been performed on cast iron. What is more, it has not been established which substances cause this effect. The purpose of the study is to determine the corrosion resistance of 08kp steel and gray cast iron SCh-15 (common structural materials of food industry equipment) in acidic and neutral environments in presence of oak bark extracts; to define the qualitative composition of the extract. Structure of cast iron and steel samples was studied on a metallographic microscope MMP-14C. The corrosion rate of metals was evaluated by weight. To determine the corrosion potential, we used a setting of a cathode voltmeter, electrodes (test and saturated chloride-silver), an intermediate vessel with a saturated KCl solution and electrolytic keys filled with the test electrolyte and saturated KCl solution (for the comparison electrode). The extract was analyzed on a Shimadzu GCMS-QP2020 gas chromatograph with mass-selective detection. Using weight method, the inhibition effect of oak shavings alcohol extract was proved in acidic and neutral corrosive environments. Under the influence of oak bark extract (5%), the stationary potential of steel 08kp has shifted: in 3% NaCl solution (oxygen depolarization) – towards more negative values; in 5% HCl solution (hydrogen depolarization) – to less negative values. Gas chromatography with mass-selective detection (GC/MS) revealed that the active substance in the extract is a mixture of natural tannins – polyphenolic compounds with a molecular weight of 500 to 3000. The inhibition effect of natural tannins is probably enhanced by siloxane compounds.