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1

Durability forecast of long rod composite insulators operating under variable mechanical loading conditions

Bielecki Jerzy, Wańkowicz Jacek

Archives of Electrical Engineering

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2022

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Vol. 71, nr 3

701--715

EN

Suspension line insulators are during their operation subject to static forces and variable loads, usually of a cyclic character. These variable loads have a significant impact on the mechanical durability of composite insulators. A method of providing durability forecast for composite line insulators based on fatigue characteristics has been proposed. The method allows providing durability forecast of insulators in a wide range of variable loadings, i.e. from quasi-static to high amplitude loadings.

2

An Ordnance Reliability and Life Model for the Estimation of the Component Kits in Preventive Replacement in Terms of Production and Operating Costs

Idziaszek Zdzisław

Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa

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2019

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Vol. 10, Nr 2 (36)

103--130

EN

This paper presents an outline of a method of optimising the service life of aircraft guns at the stage of design engineering and retrofitting. The essence of this method is a selection of service lives and quantities of preventively replaced components and the service parts of non-reconditionable components resulting in an overall reduction of gun production and operating costs (including the costs of replacement parts stocks) with an improvement of the service life of the whole gun assembly. The method assumes that the service lives to be selected must meet a criterion of predefined reliability, maximum service availability when installed aboard a combat platform (i.e. an aircraft) and the minimum time to re-use. It is pointed out that in the design engineering of preventive component replacement and the assessment of the gun selection, a criterion of total gun cost reduction shall apply; the total gun cost is construed as the cost of production/purchase and maintenance applicable to the operating mode (with the costs and time to provide replacement parts). The total gun cost should be decisive in the definition of service lives and the number of components in preventive replacement. To analyse and select the service life and the MTBR (Mean Time Between Replacements), examples of reliability and life models of guns were developed in reference to the applicable operating standards and changes in total costs. This was followed by a demonstration of an innovative model of mapping gun (production/purchase and operating) costs with a complex number plane. The method presented herein facilitates analysing and assessing the feasibility for improvement of a gun’s availability in combat field and training operations.

PL

W artykule opracowano zarys metody optymalizacji resursu lotniczej broni lufowej (w skrócie broni) w etapie jej projektowania i modernizacji. Istotą metody jest taki dobór resursów i liczby części wymienianych profilaktycznie oraz resursów części nieodnawialnych, by uzyskać sumaryczne zmniejszenie kosztów produkcji i kosztów eksploatacji broni (w tym zapasów części zamiennych) przy jednoczesnym zwiększeniu resursu całej broni. W metodzie przyjęto, że dobór resursów musi spełniać kryterium zachowania założonej niezawodności, maksymalnej dyspozycyjności na platformie bojowej (np. statku powietrznym) oraz minimalnego czasu przygotowania do powtórnego użycia. Wskazano, że przy projektowaniu profilaktycznych wymian i ocenie wyboru broni należy stosować kryterium minimalizacji kosztu całkowitego broni, tj. koszt produkcji/zakupu, jak i koszt procedur obsługowych stosowanych w danym typie eksploatacji (w tym koszt i czas pozyskiwania części zamiennych). Zakłada się, że koszt ten powinien odgrywać decydującą rolę w określeniu zarówno resursów, jak i liczby części wymienianych profilaktycznie. Do analizy i doboru resursu oraz okresów wymian opracowano przykładowe modele niezawodnościowo-trwałościowe broni w odniesieniu do ich norm użytkowania i zmiany kosztów całkowitych. Następnie pokazano innowacyjny model powiązania kosztów broni (produkcyjnych/zakupu i eksploatacyjnych) na płaszczyźnie liczb zespolonych. Zaprezentowana w artykule metoda umożliwia analizę i ocenę możliwości zwiększania dyspozycyjności broni w trakcie jej użytkowania zarówno na polu walki, jak i w procesie szkolenia.

3

A method of automotive engine life forcasting on the basis of laboratory start- ups test

Koszałka G., Niewczas A., Kordos P.

Journal of KONES

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2008

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Vol. 15, No. 2

207-215

EN

The results of previously conducted research shows that in the case of automotive engines wear accompanying engine start-ups has significant contribution to the total wear of cylinder liner. Thus, it was assumed that wear of the liner measured after high number of start-ups can be representative for given conditions of engine operation in the vehicle and can be used to forecast engine life. The paper describes a new method of automotive engine durability prediction on the basis of wear measured after so called start-ups test. The start-ups test consists of series of repeatable cycles during which engine is started-up in precisely established temperature and operates for short time with no load and then is shut down and cooled down. To conduct the new test it is indispensable to obtain data regarding start-up conditions. But these data can be precisely determined on the basis of simple measurements made on any existing engine installed in a vehicle used in expected way. Moreover, the cost of the new test is significantly lower (minimal fuel consumption, engine does not have to be installed on dynamometer stand) and duration is shorter than in the case of standard tests. Considering advantages of the new start-ups test, it can be recommended as a part of the test stand reliability research of automotive engines. The developed method is simple and short and can be a complementary one to existing standard reliability research methods.