Simulation of rolling bearing vibration in diagnostics

This article presents results on simulation of deep groove ball bearings vibrations. Contacts between rolling elements and the races can be modelled as the Hertzian contact. This contact is on-linear, thus introduces non-linear spring forces, in consequence this vibrations are non-linear. Positions of rolling elements are functions of time, thus these vibrations can be considered as parametric vibrations. In consequence rolling bearings are active non-linear elements, which excite vibrations. This approach reflects the nature of rolling bearings vibrations. The following phenomena have been observed: bistability, jump of amplitude, opposing period-doubling bifurcations “a bubble”, period-doubling bifurcations leading to chaos, bifurcation directly leading to chaos, chaotic vibrations, windows of periodic vibrations, “noisy periodicity”, and chaotic explosion. Moreover, amplitudes of vibrations have been presented against clearance. This provides an opportunity to select failure modes. Unfortunately, relations clearance-amplitude and amplitude-clearance are ambiguous, which makes machinery diagnostic a difficult issue

Rotating systems misalignment identification using fuzzy clustering method

In the phase of operation, a technical system accomplishes goals which were the reason of the system designing and creation. The execution of operation tasks by the system causes changes in the system state. The changes in the dynamic state of rotating systems can be early identified by means of vibrations measurement. Therefore, the operational tests were performed in order to register time histories of vibrations. Next, characteristics of the collected vibration signals were recorded and the most significant of them were taken as an input for further studies. The studies were performed to formulate a method of identifying the rotating systems misalignment with high reliability. The method consists in fuzzy clustering implementation. According to the method the input signals were used to formulate the fuzzy clusters of the ability and inability states of the system. Thanks to the method, it is possible to identify the operation position of the system on base of the vibration signals analysis. In the paper the proposed method was described. The results of the method application for a gas turbine engine as an example of a rotating system are also presented. It should be emphasized that the reliability of the described operation state identification is higher than other methods implemented by the authors previously

Method of modelling operation and maintenance processes in public transport systems using a certain class of stochastic processes

The study presents a method for application of the theory Markov homogenous processes for modeling of the process of vehicle operational state changes characterized by exponential distribution of their duration time. A model of operation and maintenance of vehicles used in the research object has been developed. The research object is a city bus transport system situated in the analyzed agglomeration. Stochastic process {X(t), t = 0} is a mathematical model of the process of operation and maintenance of public transport buses. The analyzed stochastic process {X(t),t = 0} has a finite phase space S, S={S1, S2, ..., Sn}. It was assumed that operation of the model is to be described by the homogeneous Markov process {X(t) : t ? R+} with a finite set of S states. The states of the analyzed stochastic process correspond to the operational states distinguished for a bus. A hypothetical computing model was built in order to illustrate the discussion and present a method for application of the developed model. The parameters of the model were estimated based on the analysis of initial results of experimental tests conducted in a real bus transport system

Impact of the epidemiological situation in Poland in 2020 on the public transport system

The use of public transport means is characterized by periodically changing phases. For a unit performing a transport task, it is important to have tools that enable the analysis and forecasting of the state of the system and facilitating decisions regarding the control of the process being carried out. During the mishap of the epidemic, many legal solutions were imposed that forced changes in the process of using public transport. The article below describes the changes and their impact on the situation in Poland

Analysis of changes in the value of selected lubricant characteristics during use

The problems connected with assessment of value changes of selected lubricants during the operation are addressed in this study. The lubricants which have been analyzed are engine oils used in internal combustion drive units of transport means. Selected results of tests of engine oils used for lubrication of passenger car drive units have been presented. The values of kinematic viscosity were determined for different temperatures. In order to evaluate the impact of the oil operation in real working conditions on the viscosity parameters, oil samples were collected from selected vehicles. The vehicles had been used in natural conditions providing transport services. Measurements of kinematic viscosity were performed by means of a rotary viscometer

Analysis of selected results of engine oil tests

The study presents selected results of viscosity tests performed for different temperatures of lubricating oil with viscosity marked as 5w30. Viscosity tests of new oil and oil right after being used have been compared. Lubricating oil used in a drive unit of a passenger car was tested. A vehicle in which oil had been changed irregularly was purposefully selected for the tests. Its mileage was over 15-20 thousand kilometers. Upon testing the vehicle mileage was above 265 thousand kilometers. The values of selected characteristics of the analyzed engine oils have been determined including: density, kinematic viscosity and viscosity index. FUNGILAB rotary viscometer was used for measurement of the oil kinematic viscosity

Method of Building a Model of Operational Changes for the Marine Combustion Engine Describing the Impact of the Damages of This Engine on the Characteristics of Its Operation Process

This article deals with the modeling of the processes of operating both marine main and auxiliary engines. The paper presents a model of changes in operating conditions of ship’s internal combustion engine. The semi-Markov decision process was used to mathematically describe the process model of the engine. The developed model describes the effect of engine damage on the characteristics of its operation. A change in the input parameters of the model can simulate the influence of internal and external factors on the course of the analyzed process. A simplified calculation example is also presented for illustration purposes. The presented method together with developed algorithms and IT tools can be used to solve a wide range of problems related to the operation of marine main engines and other marine equipment as well as maritime and port facilities. This concerns primarily the economic, risk management and operational security issues of complex technical systems, as well as the readiness and reliability analysis of technical facilities

A Method for Determining the Usability Potential of Ship Steam Boilers

Ship large-power steam boiler may serve as an example of complex critical technical system. A basis for rational control of operation of such system is knowledge on its capability of fulfilling the tasks to which it was intended. In order to make it possible to apply computer aiding to operational decision-making the capability should be described analytically. In this paper it was proposed to express the capability of ship steam boiler ( considered a complex system) to perform service tasks, by calculating components of its usability potential in a given instant t. To this end , was distinguished a set of steam boiler fundamental features which formulate space of its technical states. Values and characteristic intervals of the features were defined and this way sub-spaces of serviceability and non-serviceability states of the object in question were determined. Next, in the considered space, technical state of the boiler and its usability potential was determined. Owing to this it become possible to quantitatively express the steam boiler functioning capability which served as a basis for elaborating an algorithm for controlling the operational processes of a complex technical system under action. In this paper is also described a way of application of the presented method to calculation of ship steam boiler usability potential, which may be especially instrumental in the case of operational control of the boilers of the kind , equipped with interstage reheaters, i.e. those operating with high values of operational parameters