Changes In Technical Condition Research Articles

Development of software and hardware complex of operative diagnostics of structural part of 35-220 kV overhead lines operated in Northern regions of Western Siberia

The article is devoted to the problems of maintenance of overhead power lines in the Far North of Western Siberia. For improvement of quality and reliability of power supply of consumers in the conditions of the Far North of Western Siberia, decrease in operational costs and volumes of the carried-out emergency works the hardware-software complex for expeditious inspection, assessment and forecasting of change of technical condition of constructive part of air lines (VL) of 35-220 kV is developed, the structure of the hardware-software complex of registration of the condition of constructive part of VL of 35-220 kV and structure of the hardware-software complex of storage., processing and analysis of the obtained data on the States of the constructive part of the VL 35-220 kV.

A Multistate Model of Reliability of Farming Machinery

The article describes a multistate model of reliability of farming machinery as a deductive stochastic model of the process of changes in the technical conditions observed during operation. These conditions determine the capacity of machinery to fulfil functions, simultaneously keeping safety and maintaining acceptable costs of possible repairs. The theory of semi-Markov processes was used to solve the problem. After detailed analysis of the symptoms of damage to exemplary groups of farming machinery (rotary mowers, rotary harrows and harvesting presses) we obligatorily and arbitrarily proposed an optimal four-state reliability model to describe changes in technical conditions. In contrast to the classic reliability theory, which allows only two states of technical usability (either a machine is fit to function or not), we also allowed intermediate states, because not all types of damage affect the functionality of machinery. This approach increases the probability of technical usability of machinery and rationally delays the moment of premature repair.

Assessment of means of mechanization of construction risks using catastrophe theory

In article questions of assessment of the risks arising in the course of design, production and operation of means of mechanization of construction using catastrophe theory are considered. In the course of operation of the machine malfunctions, suddenly defiant refusals of details gradually collect. The device of the theory of accidents allows to develop models of change of technical condition and operational properties of a details material for various service conditions. In the field of space of conditions of the system containing critical signs accident emergence conditions (refusal of a detail and an emergency) are created. Assessment of probability of emergence of refusal during a certain period of operation of the machine taking into account weight of consequences allows to establish risk level.

Energy model of change in technical condition of aircraft power plants and space propulsion systems

AbstractThe publication describes an example of the energy model of change in the technical condition of aircraft power plants and space propulsion systems, which enables to shape their dependability by simultaneously ensuring the safety of flight operations and more economical operation.The approach presented in this publication has a significant research value as regards widening knowledge on shaping dependability of power plants.Further research on developing the diagnostic energy model of aircraft power plants and space propulsion systems should involve implementing in their complex structural systems the elements of artificial intelligence based on expert systems or artificial neural networks.

Technical condition change detection using Anderson–Darling statistic approach for LHD machines – engine overheating problem

In underground mine so called Load-Haul-Dump machines (LHD) plays a key role in horizontal transportation process. LHD machines execute ore haulage from mining faces to dumping points in a cyclic way. Time-varying and harsh environmental conditions determine high workload, so effectiveness demands are big challenges for maintenance staff. One of the most important issue is related to engine overheating, what is the main cause of unjustifiable loader stoppages and unwanted disturbances in production. Operator is obligated to react quickly and switch machine to idle operation until it cools down. Existing on-board monitoring systems dedicated for LHD machines provide data necessary to perform diagnostics of the engine as well as its cooling system. Understanding how load, wear level of machine and ambient temperature influence diagnostic data is the key in development of fault detection algorithms. In this paper, authors propose to use longterm temperature data. The Anderson–Darling statistic is applied in order to detect segments of different statistical properties which are related to different technical condition. Analysis of obtained two-dimensional data structure allows to find points of change of technical condition of the machine. It could be considered as training for diagnostic system that could be used for machine monitoring.

Estimation of the probability of mechanical systems breakdown by technical state modeling

This study considers the general model of estimating changes in technical state of mechanical systems caused by external action. This model makes it possible to estimate their effect on the probability of breakdowns. The considered examples include the destruction probabilities for crank rods of the opposite compressor to be simultaneously affected by cyclical loading and wear.

THE ASSESSMENT OF OBJECT USABILITY ON THE BASIS OF INSTANTANEOUS VALUES OF TECHNICAL CONDITION AND REGULATION STATE PARAMETERS

In the process of using a complex technical object, it is deregulated, worn and its reliability is decreased. Therefore, it is required that its status, technical state and reliability should be observed during its normal use and handling. The results of such observations allow a synthetic (complex) assessment of suitability of the object, determining its ability to properly carry out its tasks in accordance with its intended purpose. A continuous observation of changes of technical condition on the basis of relationship between the diagnostic signals (output) and the input signals (environment) allow evaluation of the regulation state of the object [4, 5]. An innovative method of assessment of the operated system usability presented in the article concerns an adequate analysis of the changes to aRb technical condition and aRc, regulation state current parameters formed from coupled equations of state (1 and 2) [1, 2, 3, 7]. While analysing the waveforms of instantaneous values of aRb technical condition and aRc regulation state parameters, it has been observed that parameter and instantaneous damage can be identified on the basis of quantitative relationships between the instantaneous threshold value of dpr and the corresponding instantaneous value of dpr dop, which are calculated from the following formulas (7, 8, 9). It is assumed that damage exists if for the instant i: i i prdop pr . Having the quantity of damage, reliability characteristics can be determined for every time of technical object exploitation (prior to the occurrence of catastrophic damage) [6]. d d

Изменение технического состояния гидропривода мобильных машин в процессе эксплуатации

Изменение технического состояния гидропривода мобильных машин в процессе эксплуатации

Study on the Method to Simulate the Service Life of Vehicle Based on Biological Population

Based on the similarity between the regularity for change of technical condition of vehicle and biological population, the paper builds a simulation model on the overall technical state of system vehicle, and hence sets up a state transition equation of vehicle service life and a transition equation of vehicle accumulated mileage to measure the number of retired vehicles in a system and study when the vehicle is retired and the quantity of retired vehicles. In the end, the paper verifies the practicability of this method through a case.

Empirical Mode Decomposition of Vibration Signal for Detection of Local Disturbances in Planetary Gearbox Used in Heavy Machinery System

In rotating machinery, the detection of local damage is one of the most important issues. This kind of change of technical condition produce local disturbance according to temporal (local) change of stiffness of kinematic pair (tooth-tooth contact, rolling element-outer/inner race etc). In many practical, i.e. industrial cases, vibration signature of such change is weak in sense of produced energy, so consequently, completely masked by other vibration sources in machine. The general concept of signal processing for local damage detection is to use so called signal enhancement, i.e. a kind of tool that may improve signal to noise ratio. One may find many approaches used in the literature. Most of them use signal filtering (classical, adaptive and optimal filters), decomposition (wavelets) or extraction (blind source separation). Empirical Mode Decomposition (EMD) is one of such techniques that can be used with signal decomposition problem. In this paper, EMD will be used for vibration signal decomposition in order to extract information about local perturbation of arm (carrier) in planetary gearbox used in heavy mining machine, i.e. bucket wheel excavator. As a result of application of EMD, one may obtain several time series with different properties of sub-signal. Due to predefined task, namely local disturbance detection, several criteria have been investigated in order to select the most informative empirical mode. First criterion was kurtosis calculated for every mode with very simple decision rule (max kurtosis is the best). It was found that such approach is not optimal due to some random impulses that are not related to damage. To improve results, it is proposed to combine envelope spectrum and kurtosis. If envelope spectrum contains family of components related to arm (carrier) shaft frequency and signal is spiky (kurtosis is high) result of EMD for given mode is optimal in sense of carried information. However, in this approach decision was made based on visual inspection of the envelope spectra of each mode, which is non-effective way. Finally two parameters have been proposed: 1) Pearson correlation coefficient of an empirical mode and the empirically determined local mean of original signal; 2) a relative power of an empirical mode.

Modelling of gearbox dynamics under time-varying nonstationary load for distributed fault detection and diagnosis

Abstract Fault detection and diagnosis in mechanical systems during their time-varying nonstationary operation is one of the most challenging issues. In the last two decades or so researches have noticed that machines work in nonstationary load/speed conditions during their normal operation. Diagnostic features for gearboxes were found to be load dependent. This was experimentally confirmed by a smearing effect in the spectrum. In order to better understand the involved phenomena and to ensure agreement between simulation and experimental results, two models of gearboxes (a fixed-axis two-stage gearbox and a planetary gearbox) operating under varying load conditions are proposed. The models are based on two mechanical systems used in the mining industry, i.e. the belt conveyor and the bucket wheel excavator. An original transmission error function expressing changes in technical condition and load variation is presented. Energy based parameters (the signal RMS value or the arithmetic sum of the amplitudes of spectral gearmesh components) are adopted as the diagnostic features. Simulation results show a strong correlation between load values, changes in condition and the diagnostic features. The findings are key to condition monitoring. Thanks to the use of the models one can better understand the phenomena identified through an analysis of vibration signals captured from real machines.

Digital technology and systems for generating and analyzing information from deep strata of the Earth for the purpose of interference monitoring of the technical state of major structures

A digital technology for generating seismic information from deep strata of the Earth is proposed. An intelligent hybrid distributed system is developed on the basis of the technology. By means of this system it becomes possible to combine monitoring of changes in technical state with generating warnings of every imaginable type of emergency in construction projects together with short-term prediction of earthquakes. Because of paralleling of the recognition of measurement information arriving from a set of local monitoring systems situated at significant distances from each other, the degree of reliability of the results obtained is increased.