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Thesis
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CONTRIBUTI I LA INFORMATIZAREA PROCESELOR DE MONITORIZARE A FIABILITATII
Necşulescu, Consuela
2008-06-28
Abstract: Abstract: În aceasta teza de doctorat am elaborat un sistem informatic pentru calculul si analiza indicatorilor de fiabilitate ai autovehiculelor pe baza datelor rezultate din exploatare. Cele mai importante cauze care produc defectarea componentelor auto sunt: calitatea lubrifiantilor si a combustibililor folositi în procesul de exploatare al autovehiculului, starea drumurilor, temperatura scazuta sau ridicata, socurile termice, umiditatea, praful, sarea, solicitarile mecanice de genul socuri sau vibratii, etc. Defectiunile componentelor auto pot sa apara si ca urmare a greselilor de proiectare si fabricatie, a nerespectarii conditiilor de exploatare sau din cauza proceselor de uzura, îmbatrânire, coroziune etc. S-au analizat simptomele care apar în urma defectarii sistemelor, subsistemelor si componentelor auto. Analiza fiabilitatii s-a realizat la nivelul sistemelor, subsistemelor si la nivelul componentelor auto. Aceasta analiza a fiabilitatii este realizata pe baza schemelor logice de fiabilitate ale sistemelor si subsistemelor auto. Sistemul informatic elaborat permite extragerea urmatoarelor rezultate: diagnosticarea automata prin identificarea pieselor auto defecte în functie de simptomele prezentate; calcularea parametrilor functiei Weibull pentru piesele auto; calculul indicatorilor de fiabilitate si : functia de fiabilitate, functia de defectare, densitatea de probabilitate a timpului de buna functionare, rata de defectare si media timpului de buna functionare pentru fiecare componenta, subsistem si sistem auto; trasarea graficelor pentru indicatorii de fiabilitate calculati; realizarea de statistici privind ponderea cauzelor care produc defectarea componentelor auto; vizualizarea prin intermediul graficelor a structurii cauzelor care produc defectarea componentelor auto; realizarea de statistici privind ponderea defectelor componentelor pe fiecare subsistem defect, ponderea defectelor subsistemelor pe fiecare sistem defect si ponderea defectelor sistemelor pe autovehicul; vizualizarea prin intermediul graficelor a acestor ponderi; stabilirea stocului optim de piese auto de rezerva astfel încât functia de fiabilitate a automobilelor aflate în exploatare sa fie maxima în conditii de restrictii privind costul total. Abstract: In this doctorate thesis, we drew up a data processing system for the calculation and analysis of the reliability indicators regarding the motor vehicles on the basis of the data resulted from exploitation. The most important causes which produce the injury of automotive parts are: the quality of lubricants and of fuels used in the process of car exploitation, condition of roads, low or high temperature, thermic shocks, humidity, dust, salt, mechanical stress like shocks or oscilations etc. The faults of the automotive parts can also arise owing to the errors of design work and make, to the inobservance of exploiting conditions or because of the wear, ageing and corrosion proceses etc. It has been analysed the aspect of symptoms which results from the injury of automotive subsystems and parts. The analysis of reliability was made at the level of systems, subsystems and automotive parts. This analysis of reliability is worked out on the basis of logical schemes of reliability of the motor systems or subsystems. The data processing system which was drew up allows the extract of the following results : automatic diagnosing by identification of the faulty automotive parts depending on the symptoms presented ; calculation of the Weibull function parameters for the automotive parts ; calculation of the reliability indicators as well as : reliability function , faulting function , probability density of the good-working time , faulting frequency and the mean of good-working time for each of the automotive component, subsystem and system ; tracing the diagrams for the calculated reliability indicators ; working out statistics regarding the gravity of causes which produce injuries to the automotive parts ; visualizing ,through diagrams , the structures of the causes which produce injury to the automotive parts ; elaborating statistics regarding the gravity of faults for the parts for each faulty systems ,the gravity of subsystem faults for each faulty system and the gravity of system faults for each motor vehicle ; visualizing these gravities through the diagrams ; settling the optimum stock of automotive spare parts ,so that the reliability function of the exploiting motor vehicles should be at a maximum level in conditions of restrictions regarding the total cost .
Keyword(s): Fiabilitate -- Autovehicule -- Teză de doctorat ; Baze de date -- Gestiune -- Teză de doctorat
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Record created 2016-06-21, last modified 2016-06-21
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