Modernisation of LEMACH 6 Design-Research Method as a Reliability Engineering Tool

The article presents the developed design-research method for mechanical objects, which is a modernisation of the sequential-iterative design method LEMACH 6. As part of the design process organised by method guidelines, a number of activities related to designed object’s reliability testing and engineering were included. The article charac-terises selected design methods, with particular emphasis on the LEMACH 6 method. Next, assumptions were made regarding the development and use of the proposed solution, and a diagram and detailed analysis of individual elements of the new method were presented. The developed method enables the organisation of design works, allowing one to rapidly create new solutions and avoid mistakes during designing

Journal of the European TRIZ Association - INNOVATOR

Selected papers presented at the 17th International TRIZ Future Conference Bridging Creativity in Science, Entrepreneurship, Industry and Education October 4-6, 2017, Lappeenranta, Finland

Analysis of the Modernised Railway Vehicle Component with Regard to Reliability and Operational Safety

This paper presents an analysis of the design of the bogie pivot of an electric multiple unit, which is cast in cast steel to replace the forged pivot used to date. The change in pivot manufacturing technology is justified for economic reasons, but may affect the reliability and operational safety of multiple units. The authors analysed to what extent the change in pivot manufacturing technology from forged to cast can affect the operational reliability of the upgraded structural component and what requirements should be met so that the introduced upgrade does not reduce the operational safety of the electric multiple unit. An important part of the analysis is the consideration of the effect of preventive replacements of the rubber element of the vibration damper on damage to the pivot and vibration damper system. The dependence of damage to the cooperating components of the pivot elements and vibration damper in the system is demonstrated. The lifespan of the rubber element of the damper is considerably less than that of the bogie pivot of the electric traction unit, and its damage increases the probability of damage to the cast steel pivot. This relationship is critical and, in order to ensure the required reliability of the traction unit, a strategy of preventive replacement of the rubber element of the damper was proposed and achieved in the simulation model developed. This issue is presented in this paper because it is fundamental to the safe operation of rail vehicles

Metoda szybkiej oceny niezawodności układów typu k z n

IEC 61508 standard could be used in the evaluation of safety of the k-out-of-n technical systems, including elements which may remain in one out of four different reliability states. Such a model leads to the huge complexity of analytical calculations and the limitations of its practical application possibilities. Therefore, a computerised method using Markov processes for estimating the reliability of k-out-of-n systems was developed. The algorithmization of the applied computational procedure was performed. It allowed one to analyse systems including a huge number of elements. An algorithm that may be applied for complex k-out-of-n systems was developed and used for exemplary calculations. The developed method was verified by comparing the obtained results with the ones obtained from analytical method as well as simulation method. The compatibility of results obtained in the two methods confirms the correctness of the developed procedure and proposed computer program which now offers the possibility of doing calculations for k-outof-n structures with more than three elements required for the system’s proper functioning and significantly accelerates calculations. Reliability and safety are priorities in the operation of technical systems. This decides of the applicability of the calculation methods described. The operational safety aspects are of particular significance in cases when the occurrence of a failure is a hazard to people’s health and life, ecological risk or considerable financial loss.Norma IEC 61508 może być stosowana do oceny poziomu bezpieczeństwa układów technicznych typu k z n, w których elementy mogą pozostawać w jednym z czterech różnych stanów. Przyjęcie takiego modelu prowadzi do ogromnej złożoności obliczeń analitycznych i ograniczeń w praktycznych możliwościach ich zastosowania. W związku z tym, do oceny niezawodności tego typu układów opracowano komputerową metodę wykorzystującą procesy Markowa. Następnie przeprowadzono algorytmizację opracowanej procedury obliczeniowej, co pozwoliło na analizę systemów obejmujących dużą liczbę elementów. Na podstawie opracowanego algorytmu przeprowadzono przykładowe obliczenia. Opracowaną metodę zweryfikowano porównując otrzymane wyniki z wynikami uzyskanymi metodą analityczną oraz metodą symulacyjną. Zgodność wyników uzyskanych w tych dwóch metodach potwierdza prawidłowość opracowanej procedury i proponowanego programu komputerowego, który oferuje obecnie możliwość wykonywania obliczeń dla struktur typu k z n z więcej niż trzema elementami wymaganymi do prawidłowego funkcjonowania całego systemu i znacząco przyspiesza obliczenia. Niezawodność i bezpieczeństwo są priorytetami w eksploatacji systemów technicznych i mają szczególne znaczenie w przypadkach, gdy wystąpienie awarii stanowi zagrożenie dla zdrowia i życia ludzi, powoduje ryzyko ekologiczne lub znaczne straty finansowe

Model adaptacyjnej strategii prewencyjnej odnowy złożonych obiektów technicznych

The paper presents results of the analysis of the developed models for complex technical objects preventive maintenance scheduling. Models based on two different sets of assumptions were developed. The general problem solved was to determine the joint time of preventive renewal for a group of parts or subassemblies. The purpose of the first model (the model of scheduled preventive maintenance strategy) is to determine the profitability of constant application of a previously developed preventive maintenance schedule for a part undergoing post-failure renewal. The second model (the model of adaptive strategy of a system’s preventive maintenance) allows one to determine a new joint time of preventive renewal for a group of parts each time when one of them is undergoing a post-failure renewal. The initial preventive maintenance strategy for each part or subassembly was obtained using typical tools for maintenance planning (decision-random models based on dynamic programming and Bellman’s principle of optimality). Exemplary simulation calculations with the use of both models were made and their results presented as the total maintenance costs estimated for the renewal strategies developed. The object of the analysis were the chosen geometrical features of a rail vehicle wheel changing due to its wear during operation. Based on this kind of analysis, one can choose a better preventive maintenance model for a specific application area.W artykule przedstawiono wyniki analizy opracowanych modeli do planowania odnowy profilaktycznej złożonych obiektów technicznych, które oparto o dwa różniące się od siebie zestawy założeń. Rozwiązywany problem dotyczy określenia wspólnego czasu odnowy profilaktycznej grupy części lub podzespołów złożonego obiektu. Pierwszy z opracowanych modeli (model planowej strategii odnowy prewencyjnej) pozwala określić zasadność przeprowadzenia ustalonego wcześniej, planowego odnowienia prewencyjnego części obiektu, która została już odnowiona poawaryjnie. Drugi model (model adaptacyjnej strategii odnowy prewencyjnej) umożliwia wyznaczenie najbliższego wspólnego czasu odnowy profilaktycznej grupy części, z których jedna aktualnie podlega odnowie poawaryjnej. Początkowe (wyjściowe) strategie odnowy profilaktycznej każdej części bądź podzespołu wyznaczone zostały za pomocą standardowych narzędzi do planowania odnawiania profilaktycznego (modeli decyzyjno-losowych wykorzystujących programowanie dynamiczne Bellmana). Posługując się opracowanymi modelami odnowy, przeprowadzono przykładowe obliczenia symulacyjne, których wyniki przedstawiono w postaci całkowitych kosztów obsługiwania dla każdej z uzyskanych strategii. Przedmiotem analizy były wybrane cechy geometryczne koła pojazdu szynowego, których wartości zmieniają się na skutek zużycia w procesie eksploatacji. Na podstawie tego rodzaju analiz można wybrać lepszy (tj. efektywniejszy ekonomicznie) z modeli dla konkretnego zastosowania w praktyce

A Simulation Model for Regenerated Objects with Multiparameter Evaluation of Technical Condition Reliability Estimation

The paper presents the developed simulation model allowing one to estimate the reliability of objects whose technical condition is described by a set of geometrical features. Their values change during operation because of the wearing processes of the part under consideration. The operational availability (or unavailability) of a technical object is determined by the evaluation conducted using a set of criteria referring to its analysed features. In addition, the proposed model enables one to take into account the regeneration of such objects

Assessment of the influence of preventive maintenance on the reliability and availability indexes of diesel locomotives

The article investigates the influence of preventive maintenance on the reliability and availability indexes of the railway means of transport, which also determine the economic aspects of their operation and maintenance. The research was done using the method based on fault tree analysis (FTA) and Monte Carlo simulation. The authors performed a cause and effect analysis of the occurrence of undesirable events during the operation of selected vehicles. They identified the weakest components of the rail vehicle that affect the downtime and mean availability most significantly. Specialized software including Weibull++, BlockSim, and MiniTab aided calculations were used to illustrate the application of the results of a modernization project involving a 6Dg diesel locomotive, carried out in cooperation with the biggest Polish rail carrier. The applicability of the proposed tools has been verified on the example of a selected sample of 75 diesel locomotives employing data on their use and maintenance acquired in the real operation process. The obtained results indicate that the proposed approach can be particularly useful in practice when assessing the applied rail vehicle maintenance strategy, and while developing new strategies and selecting the best one to implement