Improvement of the system of criteria for defects of machines and mechanisms by vibration-acoustic signal parameters is an urgent task of technical diagnostics. Our study is aimed at finding peculiarities and approaches towards the assessment of standard diagnostic signal parameters corresponding to various conditions of a diagnostic object. A classic approach is based on the fact that faultless condition is characterized by a certain diagnostic sign which rate increases when the machine turns faulty. Non-classic approach – condition worsening is characterized by lower rates of certain diagnostic signs. Both situations require determining correct rates of possible defect skipping and false alarm. The paper shows the methods of a correct rating of defect skipping and false alarms for various conditions of a machine and the nature of diagnostic sign changes. As an example of a diagnostic sign let us consider a module of the characteristic function of instantaneous values of a vibroacoustic signal for a set parameter of the characteristic function. This diagnostic sign is an example of the non-classic approach of rating. We used statistical methods of decision-making to rate the characteristic function module’s limiting values showing the diagnostic state. The results prove that methods of statistical decision making can be used to rate limiting values of diagnostic signs for “classic” and “non-classic” cases of probability distribution functions. That allows setting certain conditions of a diagnostic sign rating and making correct calculation of possible defect skipping and false alarm rates.
Kostyukov V.N., Naumenko A.P., Kudryavtseva I.S. Assessment of quantitative criteria for diagnostic signal parameters and limiting conditions of a diagnostic object // Proceedings of the VI School-Seminar RISKOM. - Omsk. - Publishing house "Zolotoy tirazh" (ООО "Omskblankizdat"). - 2016. - p.137-147
The paper describes a scientifically grounded system-based approach towards scientific monitoring of natural-engineering systems (NES) based on fundamental principles, laws and patterns of classic continuum and elastic-media mechanics , theory of stress-strain states, methods and instruments of condition monitoring, analysis, assessment, expertise and prediction of homeostasis in operational resource of structural integrity for such tasks as prevention of accidents, and man-made and natural-engineering disasters.
Speranksy A.A., Kosyukov A.V. Modern tools for real-time monitoring of mechanical systems // Proceedings of the VI School-Seminar RISKOM. - Omsk. - Publishing house "Zolotoy tirazh" (ООО "Omskblankizdat"). - 2016. - p.47-59
The paper provides background on vibration diagnostics in Russia, and, also, gives the reader perception on modern health monitoring system COMPACS, examples of its work and production risk matrix.
Kostyukov V.N., Kostyukov A.V. Real-time health monitoring of equipment – a breakthrough innovative technology for Russia // Proceedings of the VI School-Seminar RISKOM. - Omsk. - Publishing house "Zolotoy tirazh" (ООО "Omskblankizdat"). - 2016. - p.28-39
Asynchronous electric motor (AEM) is currently one of the most common types of electrical equipment. Consequently, there is quite an urgent issue on developing modern methods of condition diagnostics, including automated one, of the main AEM parts and stator windings in particular.
The purpose of research is to try out the method using partial discharge (PD) parameters measuring to control AEM’s winding condition in repair production, and control AEM on site.
To reach the set goal we had to solve the tasks on developing PD parameters measuring schemes in stator windings; collecting and processing the statistical data by those parameters for a large number of AEMs; characterizing PD parameter distributions and standardizing the critical values of such parameters.
An electric method of PD parameter measuring method was selected as a working method due to being more appropriate for AEMs and having greater sensitivity. As the supplementary methods, vibration diagnostics and visual control methods were used. The obtained data were processed by mathematical statistics algorithms using computer technology allowing analyzing results of more than 4300 measurements.
By the results of the research, the PD parameters were standardized in order to apply them in ARM testing.
Applying the research’s results in production practice allows increasing the depths of diagnosing ARM electric systems and improves its reliability. Detection of winding defects even at the earliest stages of their development contributes to accident prevention and decreases financial losses due to machinery idle time.
Burda E.A., Kostyukov Al.V., Boychenko S.N., Schelkanov A.V. Condition diagnostics of asynchronous motor stator’s winding by partial discharge method // Dinamika Sistem, mechanismov i machin. - 2016. - №1, v.3. - p.53-61
The paper is aimed at developing a methodology for diagnosing bearing units of rotary machines by a vibration-acoustic method of non-destruction testing with increased reliability of diagnostics and minimal costs for the testing. Diagnostics of any object always involves a chance of a false alarm or defect skipping. Skipping a defect of equipment in operation may cause destruction of a unit, processing failure and an accident. A false alarm requires additional works to be carried out. To reach the set diagnostic goal, the dependency and changes in vibration parameters and rotation frequency in various states of the equipment are calculated and registered.
Zaytsev A.V., Kostyukov V.N., Kazarin D.V. Diagnosing bearing units of rotary machines in various operating modes // Dinamika Sistem, mechanismov i machin. - 2016. - №1, v.1. - p.173-178
The article dwells upon the method for building a diagnostic model of a complex diagnostic object on the example of an electric train’s pneumatic system. The diagnostic model is built by formalizing the verbal description of the object using fuzzy logic.
Schelkanov A.V. Building diagnostic models of complex technical systems (on the example of pneumatic system of electric trains) // Dinamika Sistem, mechanismov i machin. - 2016. - №1, v.1. - p.127-132
One of the most promising trends in developing systems for vibration control, monitoring and automatic diagnostics of power units’ condition is shaft sensors application. However, turbine rotor vibration reliability criteria required for such purpose are not developed in full measure. The list of standards includes only specifications for vibration control systems and GOSTs for estimation of vibration rates at one side of a bearing journal.
The purpose of the research is to establish criteria for estimation of rotor condition and vibration reliability in operation, using full shaft sensor system as required by GOST R 55263-2012.
In this paper we formulated all main criteria necessary for condition assessment in modern systems of automatic diagnostics. We suggested threshold values for parameters used for determining the condition of shafting with bearing journals.
Kumenko A.I., Kuzminyh N.Y.,Timin A.V. Development of turbine rotor vibration reliability criteria // Dinamika Sistem, mechanismov i machin. - 2016. - №1, v.1. - p.58-64
Diagnostics of certain defects and failures of machines and mechanisms by vibration-acoustic signal parameters requires assessment of the measured signals’ peak values. Taking into account stochastic nature of such signals, the assessment of measuring errors and signals’ peak values considering distribution laws of their momentary values is an urgent task. This paper is aimed at developing a method for measuring errors assessment and calculation of vibration-acoustic signals’ peak values. As the results of analyzing a mathematical system for relative RMS random error which may occur in estimating statistical characteristics of processes there are mathematical relationships used for calculating such estimations for various distribution laws of momentary signal values. In particular, a task on determining a functional connection between asymptotic estimation of quantile sampling estimate and discreet values in a sampling (a signal’s sampling rate) is solved, allowing to justify and verify precision of measuring tools, as well as to evaluate accuracy of measurements of VA signals’ peak values.
Kostyukov V.N., Boychenko S.N., Kudryavtseva I.S., Naumenko A.P. Methodical basis of peak value assessment for vibration-acoustic signal parameters // Dinamika Sistem, mechanismov i machin. - 2016. - №1, v.1. - p.51-58
Some diagnostics problems of complex rotor systems for power turbine units are considered. A list of the main problems that must be solved for the diagnostics of technical condition of shafting on journal bearings is offered. One of the most difficult task – diagnostics of a residual deflection of separate rotors in the shaft line is also considered.
The multiple-bearing test rotor stand with journal bearings for the analysis of physical processes and development of a number of diagnostic signs of the defects measured automatically with use of the shaft encoder complete system according to GOST P 55263-2012 is offered.
The stand consisting of two rotors and a driving engine connected by rigid couplings allows to simulate and vary all main defects of production and assembly of rotors and bearings. The key geometrical and technical parameters of rotors are specified. The main dynamic characteristics of the rotor stand and results of simulation of a rotor deflection with use of the special software are provided.
Kumenko A.I., Kostyukov V.N., Suminov I.A., Kuzminykh N.I. Mathematical and physical simulation of diagnostics problem on the test rotor stand // Proceedings of CM2016/MFPT2016
It is proposed a modern concept and a set of methods for monitoring of the technical condition of system “turboset's shafting – journal bearings – support units”. Technology is developed as an integral part of domestic multipurpose COMPACS® system®. The system input data covers: - design, technological, mounting and operating parameters of the turbine unit; - absolute vibration of supports and control points of the shafting line; - relative displacement and vibration in the rotor journals according to GOST R 55263-2012. Also, the system includes as precomputed: - mounting line of the shafting in cold state; - for each journal bearing, static and dynamic properties of the bearing oil film in domain of possible motion (DPM are given; - static and dynamic properties of supports; - matrix of influence of displacements of supports on the forces in supports of the shafting.
While in operation, the methods allow to determine static and dynamic loads on the supports of turboset, to determine misalignment of supports and to evaluate corrective alignments of the supports and centering of coupling halves. Also, stress in the rotor pins, welded joints and coupling bolts are computed.. We suggest an automatic conclusion on compliance of the technical condition of turboset with safety levels, identification of source of malfunction and recommendations for necessary measures. The work covers some procedures, including ways of determination of stiffness of supports, a method of determination of above mentioned matrix of influence and a method of inverse problem solution – determination of misalignments of the supports based on determination of position of rotor journals in the bearing bores.
We have shown the results of static characteristic modeling by an example of turbine unit 1000 MW for atomic power stations.
Kostyukov V.N., Kumenko A.I., Kuzminykh N.Y., Timin A.V. Development of methodological support for turbine unit shaft defect and stress monitoring systems at thermal power stations and atomic power stations with application of shaft displacement sensors // Proceedings of CM2016/MFPT2016