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1

A concept of determining the relation between load and wear of tribological systems of ship main selfignition engines by using probabilistic approach

Girtler J.

Polish Maritime Research

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2018

|

nr 4

130--138

EN

This paper presents a proposal of simultaneous consideration of load and wear associated with it , of tribological systems of ship main engines (intended for ship propulsion) . Based on results of investigations it was assumed that both the load Q (i.e. a cause of wear ) and the wear Z (i.e. an effect of load occurrence) considered in a given time t (0 ≤ t ≤ tn) are random variables Qt and Zt ,respectively. There was characterized operational principle of ship main engines in definite external conditions (WZ) as well as consequences of excessive load of engines. Three hypotheses highlighting relations existing between load and wear of the above mentioned systems, have been proposed. The first of them deals with explanation of stochastic relation between load and wear, the second highlights why it is possible to assume that the load Qt and the wear Zt are positively correlated , and the third – why it is possible to assume that coefficient of correlation between Qt and Zt may be taken close to one.

2

Reliability and types of diagnosis in the process of diesel engine operation

Girtler J.

Journal of Polish CIMEEAC

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2018

|

Vol. 13, no 1

20--29

EN

The article presents complexity of the problem concerning development of diagnosis with defined reliability by a diagnosing system (SDG) on technical condition of marine combustion engines, especially main engines. It was shown that development of the final diagnosis, the so-called initial operation diagnosis, on the operational usability (fDG on PEx) of a main engine in particular, is not possible without prior development of reliable diagnoses such as: diagnosis on correctness of diagnostic signals, diagnosis on correctness of values of the measured diagnostic parameters of an engine (DG on pWM), diagnosis on technical condition of an engine (DG on ST) and initial diagnosis on operational usability of an engine (wDG on PEx), the so-called initial operation diagnosis. Difficulties in development of the diagnoses were emphasized herein due to the fact that the process of acquisition of information needed to develop diagnoses with certain reliability or accuracy is a two-dimensional stochastic process with components: B(t) – being considered during operation (use) of SDG (at so-called long time - quasistatic) and C(ʋ) – being considered while measuring diagnostic parameters and diagnostic inference (at so-called short time - dynamic). The need to determine reliability or accuracy rate of each diagnosis in the form of conditional probability P(S/K) was also indicated, where S – technical state of the engine and K – vector of values of diagnostic parameters reflecting state S. Diagnostic status of marine engine as a diagnosed system (SDN) was characterized in general, on the example of an engine operation process with regards to input (X), output (Y), constant (C) and interference (Z) values. Also there was explained how to understand the terms: diagnostic test, signal inference, measurement inference, structure inference and operation inference, and how inductive inference can be used to verify, for example, the hypothesis H on engine state S when vector K of values of engine diagnostic parameters is observed.

3

Energetyczne ujęcie działania komór spalania okrętowych silników spalinowych tłokowych i turbinowych

Girtler J.

Journal of Polish CIMEEAC

|

2018

|

Vol. 13, no 1

30--46

PL

Przedstawiono propozycję wartościowania (ilościowego określenia) działania komór spalania tłokowych i turbinowych silników spalinowych z uwzględnieniem zachodzących w nich takich rodzajów przemiany energii jakimi są ciepło i praca. Przedstawione rozważania bazują na fakcie, że w komorach spalania tego rodzaju silników spalinowych zachodzi przekształcanie energii chemicznej zawartej w dostarczonym do niej paliwie (ściślej – energii chemicznej zawartej w mieszaninie paliwowo-powietrznej powstałej w tej komorze) na energię wewnętrzną spalin powstających podczas spalania paliwa. Ta forma przemiany energii została nazwana ciepłem indykowanym (Qi). Ciepło Qi odniesione do jednostki czasu t spalania paliwa zostało nazwane strumieniem ciepła ( Qi). Zwrócono uwagę, że proces spalania paliwa w komorach spalania obu rodzajów silników może być nieprawidłowy, w przypadku niewłaściwego działania ich wtryskiwaczy, co jest równoznaczne z nieprawidłowym działaniem tych komór. Działanie dowolnej komory tłokowego bądź turbinowego silnika spalinowego zostało w tym artykule zinterpretowane, jako przetwarzanie energii chemicznej zawartej w paliwie na energię wewnętrzną powstających spalin podczas spalania paliwa w ustalonym czasie. Wartościowanie tak rozumianego działania komór spalania tego rodzaju silników spalinowych, zaproponowane przez autora tego artykułu, polega na określeniu ilościowym tego działania za pomocą wielkości fizycznej, którą cechuje wartość liczbowa z jednostkę miary nazwaną dżulosekundą [dżulxsekunda]. Do oceny procesu pogarszania się działania komór spalania dowolnego tłokowego bądź turbinowego silnika spalinowego zaproponowano model w formie jednorodnego procesu Poissona.

4

Features of load and wear of main propulsion devices on sea-going ships with piston combustion engines and their impact on changes in technical states of the systems

Girtler J.

Polish Maritime Research

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2017

|

nr 4

57--66

EN

The paper presents the specificity of operation of propulsion systems of seagoing ships which causes the need to control the load on them, especially on their engines called main engines. The characteristics of the load on the propulsion systems, especially on the main engines as well as on the shaft lines and propellers driven by the engines, along with the process of wear in tribological joints (sliding tribological systems) of the machines have been described herein. Using examples of typical types of wear (both linear and volumetric) for the tribological systems of this sort, interpretation of states of their wear has been provided with regards to the wear levels defined as acceptable, unacceptable and catastrophic. The following hypotheses have been formulated: 1) hypothesis explaining necessity to consider the loads on the systems under operation as stochastic processes; 2) hypothesis explaining a possibility of considering the processes as stationary; and 3) hypothesis explaining why it can be assumed that a given technical state of any tribological system can be considered as dependent only on the directly preceding state and stochastically independent of the states that existed earlier. Accepting the hypotheses as true, a four-state continuous-time semi-Markov process has been proposed in the form of a model of changes in condition of a propulsion system (PS) of any ship. The model includes the most significant states affecting safety of a ship at sea, such as: s0 – PS ability state, s1 – PS disability state due to damage to the main engine (ME), s2 – PS disability state due to damage to the shaft line (SL) and s3 – PS disability state due to damage to the propeller (P). Probability of occurrence (changes) of the states has also been demonstrated.

5

Analysis of catalitic reactors usefulness to reduce pollution generated by piston combustion engines with regard to ship main engines

Zielińska E., Girtler J., Lejda K.

Polish Maritime Research

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2017

|

nr 1

81--87

EN

The article presents results which indicate that the use of catalytic reactors to reduce emissions of harmful compunds contained in the exhaust gas is important in the operation of vehicle motors operation. Efforts of the shipbuilding industry to reduce the toxicity of exhaust gas emitted by the main engines have been indicated and pointed to the desirability of the use of these catalysts in maritime transport. It has been pointed out that studies of the harmful substances in exhaust gases performer at vehicle inspection stations have an impact on increasing the safety of drivers and other road users and contribute to preserving the natural environment by reducing the danger coming from cars operating on Polish roads. An opinion has been expressed that the most serious threats to the environment are emitted by car transport exhaust fumes, which are characterized by significant emission of toxic compounds excreted into the atmosphere from tailpipe emissions. It has been demonstrated that a fully functioning catalytic reactor, operating in a steady state at appropriate temperatures and the composition of the mixture close to stoichiometric ratio, can reduce emissions of carbon monoxide, hydrocarbons and nitrogen oxides by more than 90%. Also, an assessment has been presented reporting the efficiency of catalytic reactors of spark ignition engines operating in a test vehicle inspection station. The results of research in the evaluation of their performance were correlated with their operation waveforms. Such an approach is justified by the fact that during the operation of each vehicle the wear of its assemblies and components is different – including the catalytic reactor. The catalytic layer undergoes aging so that there are changes in the structure and chemical composition of the catalyst bed, while the overlapping of layers of different chemical compounds that block access to the active layer of the reactor. An opinion has also been expressed that it would be advisable to take steps to use research results presented in this article for research of catalytic reactors similar use in diagnostic systems of marine combustion engines, especially the main ones, which exhaust emissions are incomparably greater than in the case of car engines.

6

Determination of probabilities defining safety of a sea-going ship during performance of a transportation task in stormy weather conditions

Girtler J.

Journal of Polish CIMEEAC

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2017

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Vol. 12, no 1

21--30

EN

The paper presents the possibility of applying the theory of semi-Markov processes to determine the limiting distribution for the process of changes of technical states being reliability states of the systems of sea-going ships significantly affecting safety of such ships, which include main engine, propeller and steering gear. The distribution concerns the probabilities of occurrence of the said states defined for a long time of ship operation (t → ∞). The considered states are as follows: s0 – full ability state of the systems, i.e.: main engine, propeller and steering gear, s1 – inability state of the main engine, s2 – inability state of the propeller, s3 – inability state of the steering gear. Significance of the systems for safety of the ships at sea was demonstrated herein. General conditions for performing transportation tasks by the ships, with particular regard to stormy conditions, were also here described.

7

Operation evaluation method for marine turbine combustion engines in terms of energetics

Dzida M., Girtler J.

Polish Maritime Research

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2016

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nr 4

67--72

EN

An evaluation proposal (quantitative determination) of any combustion turbine engine operation has been presented , wherein the impact energy occurs at a given time due to Energy conversion. The fact has been taken into account that in this type of internal combustion engines the energy conversion occurs first in the combustion chambers and in the spaces between the blade of the turbine engine. It was assumed that in the combustion chambers occurs a conversion of chemical energy contained in the fuel-air mixture to the internal energy of the produced exhaust gases. This form of energy conversion has been called heat. It was also assumed that in the spaces between the blades of the rotor turbine, a replacement occurs of part of the internal energy of the exhaust gas, which is their thermal energy into kinetic energy conversion of its rotation. This form of energy conversion has been called the work. Operation of the combustion engine has been thus interpreted as a transmission of power receivers in a predetermined time when there the processing and transfer in the form (means) of work and heat occurs. Valuing the operation of this type of internal combustion engines, proposed by the authors of this article, is to determine their operation using physical size, which has a numerical value and a unit of measurement called joule-second [joule x second]. Operation of the combustion turbine engine resulting in the performance of the turbine rotor work has been presented, taking into account the fact that the impeller shaft is connected to the receiver, which may be a generator (in the case of one-shaft engine) or a propeller of the ship (in the case of two or three shaft engine).

8

A model of fuel combustion process in the marine reciprocating engine work space taking into account load and wear of crankshaft-piston assembly and the theory of semi-Markov processes

Girtler J.

Polish Maritime Research

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2016

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nr 3

50--57

EN

The article analyses the operation of reciprocal internal combustion engines, with marine engines used as an example. The analysis takes into account types of energy conversion in the work spaces (cylinders) of these engines, loads of their crankshaft-piston assemblies, and types of fuel combustion which can take place in these spaces during engine operation. It is highlighted that the analysed time-dependent loads of marine internal combustion engine crankshaftpiston assemblies are random processes. It is also indicated that the wear of elements of those assemblies resulting from their load should also be considered a random process. A hypothesis is formulated which explains random nature of load and the absence of the theoretically expected detonation combustion in engines supplied with such fuels as Diesel Oil, Marine Diesel Oil, and Heavy Fuel Oil. A model is proposed for fuel combustion in an arbitrary work space of a marine Diesel engine, which has the form of a stochastic four-state process, discrete in states and continuous in time. The model is based on the theory of semi-Markov processes.

9

Application of semi-Markov processes for evaluation of diesel engines reliability with regards to diagnostics

Girtler J.

Journal of Polish CIMEEAC

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2016

|

Vol. 11, no 1

47--53

EN

The paper presents semi-Markov models of technical state transitions for diesel engines, useful for determination of their reliability, as a result of the conducted statistical empirical studies. Interpretation of technical states provided for this sort of engines refers to ship main engines, i.e. engines employed in propulsion systems of sea-going ships. The considerations recognize diesel engine as a diagnosed system (SDN), of which state can be identified by a diagnosing system (SDG). Both of the systems: SDN and SDG compose a diagnostic system (SD). Examples of three-state semi-Markov models were applied to demonstrate that in case of use of proper diagnosing systems (SDG) for identification of technical states of such engines as SDN, by classification of the states to the relevant class of the reference states, it is possible to make use of a Markov model to determine reliability of the engines. For developing a Markov model of state transitions for the engines, there were applied functions of the risk of damage: λ12 that causes transition from state s1 to state s2, and λ13 that causes transition from state s1 to state s3, as well as intensity functions of recovery (restitution): λ21 that causes transition from state s2 to state s1, and λ31 that causes transition from state s3 to state s1.

10

Identification of damages of tribological associations in crankshaft and piston systems of two-stroke internal combustion engines used as main propulsion in sea-going vessels and proposal of probabilistic description of loads as causes of these damages

Girtler J.

Polish Maritime Research

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2015

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nr 2

44--54

EN

The article discusses damages of essential tribological associations in crankshaft and piston systems of large power two-stroke engines used as main engines, which take place during transport tasks performed by those ships. Difficulties are named which make preventing those damages impossible, despite the fact that the technical state of engines of this type is identified with the aid of complex diagnostic systems making use of advanced computer technology. It is demonstrated that one of causes of the damages is the lack of research activities oriented on recognising random properties of the loads leading to those damages. A proposal is made for the loads acting at a given time ton tribological associations in crankshaft and piston systems of internal combustion engines used as main engines to be considered as random variables Qt. At the same time the loads examined within a given time interval tr ≤ t ≤ tz would be considered stochastic processes {Q(t): t ≥ 0}. Essential properties of the loads of the abovementioned tribological associations are named and explained by formulating hypotheses which need empirical verification. Interval estimation is proposed for estimating the expected value E(Qt) of the load Qt acting at time t. A relation is indicated between the mechanical load and the thermal load acting on tribological associations in the ship main engine crankshaft and piston system. A suggestion is formulated that a stochastic form of the relation between these types of load is to be searched for, rather than statistic relation, and a proposal is made to measure the intensity (strength) of the stochastic relation using the Czuprow’s convergence coefficient.

11

Application of acustic emission for detection of fatigue microdemage in main and crank bearings for diesel engines

Girtler J.

Journal of Polish CIMEEAC

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2015

|

Vol. 10, no 1

63--74

EN

The article presents reasons for applying the acoustic emission (AE) to detect fatigue microdamage in main bearings and crank bearings of marine main engines. Problem of determination of fatigue life for slide bearing bushes was characterized in general. There were demonstrated properties of the objects of research, which were bushings made of the MB58 alloy, as well as an overall description of the research. It was shown that the frequency bands of AE signals can indicate fatigue damage to the sliding layer of a bearing bush. The fatigue damage in the tested bushes was depicted in figures. General features of the AMSY-6 measuring system, used in the research, were also provided herein.

12

Possibility of estimating the reliability of diesel engines by applying the theory of semi-Markov processes and making operational decisions by considering reliability of diagnosis on technical state of this sort of combustion engines

Girtler J.

Combustion Engines

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2015

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R. 54, nr 4

57--66

EN

The paper presents semi-Markov models of technical state transitions for diesel engines, useful for determining the reliability of engines. A possibility of application of a three-state model with a simplified matrix function, or even a two-state model, to determine reliability of the engines, has been described herein on examples of known from literature semi-Markov models, for the case when appropriate diagnosing systems (SDG) are used to identify the technical condition of the engines considered as diagnosed systems (SDN). A risk function and a renewal (restitution) function have been proposed for developing a two-state model of engine state transitions. An opportunity for considering the reliability of diagnosis for making operational decisions by applying the statistical decision theory, has also been presented. Conditional probability P(si/Ki) is recognized as a measure of reliability of diagnosis.

PL

W artykule przestawiono semimarkowskie modele zmian stanów technicznych silników o zapłonie samoczynnym, przydatne do określenia niezawodności tych silników. Wykazano, na przykładzie znanych z literatury modeli semimarkowskich, że do określenia niezawodności tych silników możliwe jest zastosowanie modelu trójstanowego o uproszczonej macierzy funkcyjnej, a nawet modelu dwustanowego, przy zastosowaniu odpowiednich systemów diagnozujących (SDG) do identyfikacji stanu technicznego wspomnianych silników jako systemów diagnozowanych (SDN). Do opracowania dwustanowego modelu zmian stanów silników zaproponowano wykorzystanie funkcji ryzyka i funkcji intensywności odnowy (restytucji). Przedstawiono także możliwość uwzględnienia wiarygodności diagnozy przy podejmowaniu decyzji eksploatacyjnych w sytuacji zastosowania statystycznej teorii decyzji. Za miarę wiarygodności diagnozy przyjęto prawdopodobieństwo warunkowe P(si/Ki).

13

Application of theory of semi-Markov processes to determining distribution of probabilistic process of marine accidents resulting from collision of ships

Girtler J.

Polish Maritime Research

|

2014

|

nr 1

9--13

EN

In this paper is presented possible application of the theory of semi-Markov processes to elaborating an eight-state model of the process of occurrence of serviceability state and unserviceability states of sea-going ships making critical manoeuvres during their entering and leaving the ports. In the analysis it was taken into account that sea-going ships are in service for a very long time t (t → ∞). The model was elaborated to determine the probability (P0) of correct execution of critical manoeuvres during ship’s entering and leaving the port as well as the probabilities Pj(j = 1, 2, 3, …, 7) of incorrect execution of critical manoeuvres by a ship, that leads to marine accidents. It was assumed that such accidents result from: ship’s grounding on port approaching fairway, collision with a ship on port approching fairway, collision with a pierhead during passing through port entrance, collision with a hydrotechnical structure during ship’s passing through port channels, collision with a port quay during coming alongside it and collision with a ship already moored to the quay. The probability (P0) was assumed a measure of safe execution of a critical manoeuvre. The probability characterizes possibility of avoiding any collision during ship’s entering and leaving the port. The probability Pa = 1 – P0 was assumed a measure of occurrence of a collsion and - consequently - marine accident. The probability Pa was interpreted as a sum of the probabilities Pj(j = 1, 2, 3, …, 7) of occurrence of all the selected events. In summing up the paper, attention was drawn to its merits which - in opinion of this author - are crucial for research on real process of accidents during entering the port and leaving it by sea-going ship in difficult navigation conditions.

14

Usefulness of semi-Markov processes as models of the operation processes for marine main engines and other machines of ship power plants

Girtler J.

Journal of Polish CIMAC

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2014

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Vol. 9, no 2

57--67

EN

The paper describes the properties of semi-Markov processes and the opportunities and benefits from their use as models of operation processes for marine combustion engines and other machines of ship power plantshe importance of the theory of semi-Markov processes for development of the theory of marine combustion engines and other machines of ship power plants, as well as for development of progress of the machinessefulness of the theory of semi-Markov processes theory and operational practice of ship main engines and other machines of ship power plants to define reliability and safety indexes for the machinesonditions with regard to the properties of semi-processeswhich should be satisfied models of the real processes running during operation of marine main engines and other machinery. The suitability of decision (semi-Markov processes for making operating decisions is also proved herein, as their aim is to obtain a rational process of operation engines . the . The emphasis is put on tthe operational . The uin the is exposed, operational . There are defined the cMarkov , to enable the use of them as ship’s controlled) of the mentioned and machines.

15

Possibility of assessment of operation of sliding bearings in piston-crank mechanisms of diesel engines with regard to load and time of correct work of the bearings by applying acoustic emission as a diagnostic signal

Girtler J., Darski W.

Journal of Polish CIMAC

|

2014

|

Vol. 9, no 2

69--82

EN

The paper presents a possibility of determining (assessing) operation of sliding bearings with multilayer bushings in crank-piston mechanisms of diesel engines. Properties of load and wear, particularly fatigue and abrasive, are characterized in general. Acoustic emission as a diagnostic signal was proved to be useful for detection of the wear of sliding and barrier layers. Results of measurements of acoustic emission parameters, made with AMSY-5, the 12-channel system, manufactured by Vallen GmbH are presented herein. The measurements include such parameters as: the number of discrete emissions determined by counts of EA events, the effective value (RMS), the number and also the rate per unit of time of oscillating above the threshold level (the number of exceeding the threshold level), amplitude of discrete emission signal, rise time, duration time and damping time of discrete emission, power (energy unit) of discrete emission signal. The usefulness of acoustic emission (AE) application as a diagnostic signal for detection of micro-damage in sliding and barrier layers of bearings in crank-piston mechanisms of diesel engines was confirmed.

16

The semi-Markov model of the process of appearance of sea-going ship propupsion system ability and inability states in application to determining the reliablity of these systems

Girtler J.

Polish Maritime Research

|

2013

|

nr 4

18--24

EN

The article presents possible application of the theory of semi-Markov processes in creating the eight-state model of the process of appearance of the propulsion systems ability and inability states on sea-going vessels performing transportation tasks in a relatively long operating time t (t → ∞). The model has been proved to be able to be successfully used for determining the reliability of the abovementioned systems. The probability of faultless operation in time t was assumed the measure of system reliability. Operating situations of sea-going vessels were characterised, with special attention being paid to the fact that the loads of propulsion system components of these vessels are of random nature. These loads lead to damages which for this reason were also considered random events. It was also assumed that the damages provoke the appearance of states of inability of particular ship propulsion system components which means that these states are random events as well. The states of ability of a given ship propulsion system have been assumed to exist when all components of this system are in the state of ability. In case when at least one component is in the state of inability, the entire system is in the state of inability. Conditions were formulated for the reliability model of an arbitrary system to be able to be worked out in the form of the semi-Markov process. The need for the use of technical diagnostics in reliability examination of sea-going ship propulsion systems was indicated. In conclusions, certain qualities of the article were highlighted which are, in author’s opinion, of highest importance in reliability examination of sea-going ship propulsion systems.

17

Possibility of identification of technical condition of bearings for self-ignition engines by application of acoustic emission as a diagnostic signal

Girtler J.

Journal of Polish CIMAC

|

2013

|

Vol. 8, no 2

13--22

EN

This paper presents the results of empirical studies where the acoustic emission (AE) method was applied to identify the technical condition of sliding surfaces of main and crank bearings for main diesel engines. The test results indicate that the measurements of the AE parameters allow the technical condition identification for bearings of this type. The results refer to the measurements of the parameters for AE generated in the bearings whose sliding surfaces are in various conditions. The results illustrate the changes in AE parameters over time, like RMS (Root Mean Square), hits, counts, and also signal energy, amplitude, radial loads on bearing, friction torque, time of the mixed friction occurrence, rotational speed, temperature of bearing shell and oil film. It has been shown that AE can be an important diagnostic signal that allows disclosure of changes in technical condition of bearings in piston-crank mechanisms for the mentioned engines, in the early stages of the changes.

18

Application of the theory of semi-markov processes to determine a limiting distribution of the process of changes of ability and inability states of fuel supply systems in heavy fuel diesel engines

Girtler J.

Journal of Polish CIMAC

|

2013

|

Vol. 8, no 1

39--48

EN

The paper presents applicability of the theory of semi-Markov processes to determine a limiting distribution of the process of changes of technical states of fuel systems for marine engines running on heavy fuel oils. The proposed study of this process includes the components of such fuel systems like: 1 - injectors, 2 - high pressure hoses, 3 - injection pumps, 4 - low pressure hoses, 5 – fine filters, 6 - coarse filters, 7 – fuel-feed pump, 8 – fuel heater and 9 – viscosistat with a viscometer. A semi-Markov state transition model consisting of ten states has been developed for such systems. Application of technical diagnostics has been pointed to be necessary to investigate the state transition process for the systems. The conclusions presented furthermore in the paper provide advantages which (according to the author) are of the most importance in the design and operation phases of fuel systems in marine diesel engines that run on heavy fuel oils.

19

Four-state stochastic model of changes in the reliability states of a motor vehicle

Girtler J., Ślęzak M.

Eksploatacja i Niezawodność

|

2013

|

Vol. 15, no. 2

156-160

EN

The properties of semi-Markov processes have been generally characterized and the applicability of the theory of such processes to the determining of the reliability of motor cars and other road vehicles has been explained. A formal description of the process of changes in the motor vehicle technical states considered as reliability states and a model of this process in the form of a one-dimensional stochastic process have been presented. The values of this process are the technical states of the motor vehicle in question that have significant practical importance. A four-state set of states interpreted as follows has been adopted: full (complete) serviceability, partial (incomplete) serviceability, task-limiting serviceability,and complete (total) unserviceability. Based on the initial distribution adopted and the functional matrix worked out, the boundary distribution of the process of changes in the technical (reliability) states of the motor vehicle has been defined. The probability of the vehicle being fully serviceable has been considered a measure of the vehicle reliability for a long period of vehicle operation. A possibility of defining the vehicle reliability in the form of a probability that a task would also be fulfilled by the vehicle being partially serviceable has also been indicated.

PL

W artykule scharakteryzowano ogólnie własności procesów semimarkowskich i uzasadniono możliwości ich zastosowania do określenia niezawodności samochodów i innych pojazdów drogowych. Przedstawiono formalny opis procesu zmian stanów technicznych samochodów uznanych za stany niezawodnościowe oraz model tego procesu w postaci jednowymiarowego procesu stochastycznego. Wartościami tego procesu są występujące w czasie eksploatacji stany techniczne samochodów, mające istotne znaczenie praktyczne. Przyjęto czterostanowy zbiór stanów o następującej interpretacji: stan zdatności pełnej (całkowitej), stan zdatności częściowej (niepełnej, niecałkowitej), stan niepełnej zdatności zadaniowej i stan niezdatności pełnej (całkowitej). Na podstawie przyjętego rozkładu początkowego i opracowanej macierzy funkcyjnej został określony rozkład graniczny procesu zmian stanów technicznych (niezawodnościowych) samochodu. Prawdopodobieństwo istnienia stanu zdatności pełnej (całkowitej) samochodu zostało uznane za miarę jego niezawodności w długim okresie czasu eksploatacji. Wskazano też na możliwość określenia niezawodności samochodu w formie prawdopodobieństwa, w którym uwzględniony został przypadek wykonania zadania przez samochód także wtedy, gdy znajduje się on w stanie zdatności częściowej.

20

Problemy oszacowania trwałości i niezawodności silników o zapłonie samoczynnym z zastosowaniem teorii procesów semimarkowskich i diagnostyki

Girtler J.

Combustion Engines

|

2013

|

R. 52, nr 3

359--366

PL

W artykule przestawiono znaczenie trwałości i niezawodności silników o zapłonie samoczynnym w eksploatacji systemów technicznych, w których są zastosowane. Wykazano, że do oszacowania trwałości i niezawodności wspomnianych silników bardziej przydatne są modele opracowane w formie semimarkowskiego procesu zmian stanów technicznych tego rodzaju silników w porównaniu do modeli proponowanych w klasycznej teorii niezawodności. Scharakteryzowano możliwości zastosowania modeli semimarkowskich do badań trwałości i niezawodności tych silników. Uzasadniono konieczność zastosowania diagnostyki technicznej w tego rodzaju badaniach. Przedstawiono przyczyny powodujące niepewność sformułowania właściwej diagnozy ze szczególnym uwzględnieniem czynników wpływających na błędy pomiarów, ale przede wszystkim na niedokładność pomiarów wykonywanych podczas badań diagnostycznych. W podsumowaniu tego artykułu zwrócono uwagę na te walory, które (zdaniem autora) mają najistotniejsze znaczenie w fazie projektowania i eksploatacji silników o zapłonie samoczynnym, szczególnie stosowanych w siłowniach okrętowych jako silniki napędu głównego statku (silniki główne).