Processing of strain gauge control signals by the Kalman filter

One of the methods for detecting defects in the rolling surface of the wheels of freight cars is to measure the deformations of the rail under the passing train. The method is based on the analysis of a strain gauge signal. The main task of the strain gauge signal analysis is the selection of informative components and the removal (filtering) of interference. The paper presents methods of filtering diagnostic signals of strain gauge control and the selection of informative components. The useful signal component can be used to measure the mass of cars, to determine the dynamic load on the rails and to detect defects in the rolling surface of the wheels. The method of adaptive Kalman filtering and linear convolution are proposed as signal processing tools. Based on these algorithms, a software module based on the.NET Framework has been developed using the C# programming language. The algorithms were tested on the signals received when the train was moving along the active section of the track, with a strain gauge control system located on it. The computational complexity and speed of the algorithms are assessed, and the possibility of their further application in the autonomous mode of the system is investigated. The results show that the use of the Kalman filtering algorithm provides a significant performance advantage over the linear convolution algorithm.

EXPERIMENTALSTUDY OF DYNAMIC EFFORTS DURING THE OPERATION OF THE MECHANISM OF MOVEMENT OF THE CARGO TROLLEYOF AN OVERHEAD CRANE

The article deals with the determination of the dynamic loads arising in the running wheels of a conventional (standard) and modernized design during the movement of the cargo carriage of an overhead crane. The redesigned wheel has an insert made from 7-7130 rubber compound. Also, a method for diagnosing running wheels of conventional and modernized design was determined. The ZETLAB program was chosen as a program for signal registration and analysis. This program allows not only displaying the signal in real time with the possibility of scaling, but also allows you to digitize the signal with the possibility of further processing the results in various standards. Finding out the occurrence of a defect in wheels and rails is mainly carried out by two methods, when shock pulses appear and according to an increased background of vibration. In practice, there is a process of "dry" rolling friction, and this means that the method of shock pulses for diagnosing the condition of wheels and a rail track can be used only in some cases in the form of extreme wear of the friction pairs of a wheel and a rail. That is, the method of spectral analysis of fluctuations in the power of random vibration can be successfully applied to diagnose the state of the rail track and crane wheel. The diagnostic method based on the overall vibration level allows for an overall assessment of the technical condition. Such diagnostics makes it possible to identify defects only at the very last stage of development, when they lead or have already led to partial destruction of the rolling surface of the wheel and the surface of the rail, that is, to an increase in the overall level of vibration. The performance evaluation criteria are fully focused on the corresponding standard vibration levels for the investigated friction pair. A friction pair is considered to be defective, the vibration of which exceeds the general standard. When determining an increased overall level of vibration, maintenance personnel must make a decision to replace parts or a unit to prolong its operation. The results obtained indicate the advisability of using the wheels of the modernized design on the cargo carriage of an overhead crane.

On the Issue of Determining Relative Rail Rolling Contact Fatigue Damageability

Adoption of heavy haul traffic on many railroads, comprising Russian railways, has highlighted the relevance of assessing the effect of increased axial loads on the contact fatigue life of rails.The article describes a set of theoretical studies carried out to create a scientifically substantiated method for predicting the contact fatigue life of rails depending on the values of axial loads. The stress-strain state of the contact area has been determined using the finite element model of wheel rolling on a rail. It has been found that the wheel-rail rolling contact area undergoes complex multiaxial loading with the simultaneous action of normal and shear strains. Based on the analysis of models describing multiaxial fatigue damage, the Brown–Miller model was chosen, which considers the simultaneous action of normal strains at the contact area and of maximum shear strains, which most fully describes the stress-strain state of the wheel-rail rolling contact area. To apply the Brown–Miller model, fatigue stress-strain curves for rail steel have been identified. Based on the analysis of methods for determining the parameters of stress-strain curves carried out by V. A. Troschenko, a modified Roessle– Fatemi hardness method has been applied. Based on the experimentally determined values of hardness on the rolling surface, the parameters of the curves of elastic and plastic fatigue have been revealed by calculation and experiment. To establish the damaging effect of the load from wheel rolling on a rail, the concept of relative damage per rolling cycle had been assumed which is the value inverse to the number of cycles preceding formation of a contact-fatigue crack at a given value of the axial load.Calculations of the relative damage rate of the rolling surface of rails caused by contact fatigue defects were carried out with the Fatigue software package considering mean values of the indicators of the degree of fatigue strength and plasticity of rail steel and the calculated stresses in the wheel-rail contact area, as well as the plasticity correction using Neuber method. The polynomial dependence of relative damageability of the rolling surface of rails is obtained. The established functional dependence of relative damageability of the rolling surface of rails on the values of vertical forces can be used as the basis for the developed methodology for predicting the contact fatigue life of rails.

Increasing Service Life of a Railway Wheel with Surface Hardening Technology

The article presents surface hardening technology as applied to solid-rolled wheels of rolling stock. The obtained results of the theoretical study on the process of strengthening the metal of the wheel will make it possible to develop scientifically grounded technological and technical solutions to prevent formation and development of defects on the rolling surface, as well as to eliminate them during maintenance.The objective of this work is to identify the optimal method for surface hardening of a railway wheel with defects.At present, the issue of extending service life of elements and critical parts of rolling stock is becoming increasingly acute. Due to the limited economic feasibility and limited availability of existing production technologies, it becomes necessary to create a new material modified with nanoclusters and hardened with surfactants.Nanoclusters have high plasticity and hardness values. To determine the hardness value of nanomaterials, the Vickers hardness test method is used, in which hardness is determined by the size of the area of the indentation after removing the load from the pyramid shaped diamond.Superplasticity is observed in nanostructures. For nickel and nickel-aluminium alloy NiAl3, low-temperature superplasticity is observed in the temperature range 450–470°C, which is three times lower than their melting point.

Best practices about rail defects: a review of the book “Defects of rails. Stresses and Damages”, Vol. 1 by K.-O. Edel, G. Budnitskiy, T. Schnitzer

The review analyzes a monograph published by Springer Vieweg publishing house, which presents scientific approaches to the problems of defect formation in railway rails. The advantages of the book under review include the analysis of statistical data on rail failures, description of test methods and damage diagnostics. The book discusses in detail the widely occurring types of contact-fatigue defects formed during operation in the rail head: internal longitudinal shelling, multiple parallel head checks, surface squats und studs in the middle of the rolling surface with a greater or lesser degree deformations

REQUIREMENT FOR THE TOP STRUCTURE OF THE ROADS ON HIGH SPEED RAILWAYS

Goal: Consider the issue of the requirement for the upper structure of the track on high-speed railways in the Republic of Uzbekistan. Methods: For reliable operation, the rails must be sufficiently strong, durable, wearresistant, hard and at the same time not fragile, since they perceive the shock-dynamic load. The material for the rails is high-strength carbon steel. Results: One of the main features of a continuous welded track is that wellfixed rail strings cannot change their length when the temperature rises or falls. Because of this, significant longitudinal tensile or compressive forces arise in them, which in hot weather can lead to the ejection of the path to the side, and in severe frost - to a fracture of the lash with the formation of a dangerous gap. Practical significance: An analysis from an experimental study shows the use of a continuous-welded track is especially effective on sections of high-speed train traffic, where increased requirements are imposed on the upper structure of the track. Particular attention is paid to the prevention and elimination of wavy wear of the rolling surface of the rails, which is eliminated by grinding them with special rail-grinding trains. The developed techniques can be recommended for practical use.