Wyniki wyszukiwania - BazTech

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Component Maintenance Strategies and Risk Analysis for Random Shock Effects Considering Maintenance Costs

Zhang Chao, Zhang Yadong, Dui Hongyan, Wang Shaoping, Tomovic Mileta M.

Eksploatacja i Niezawodność

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2023

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Vol. 25, no. 2

art. no. 162011

EN

Maintenance can improve a system’s reliability in a long operation period or when a component has failed. The reliability modeling method that uses the stochastic process degradation model to describe the system degradation process has been widely used. However, the existing reliability models established using stochastic processes only consider the internal degradation process, and do not fully consider the impact of external random shocks on their reliability modeling. Furthermore, the existing theory of importance does not consider the actual factors of maintenance cost. In this paper, based on the reliability modeling of random processes, the degradation rate under the influence of random shocks is introduced into the time scale function to solve the impact of random shocks on product reliability, and two cost importance measures are proposed to guide the maintenance selection of the components under limited resources in the system. Finally, a subsystem of an aircraft hydraulic system is analyzed to verify the proposed method’s performance.

2

Importance measure-based maintenance strategy considering maintenance costs

Zhang Chao, Zhang Yadong, Dui Hongyan, Wang Shaoping, Tomovic Mileta M.

Eksploatacja i Niezawodność

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2022

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Vol. 24, no. 1

15--24

EN

Maintenance is an important way to ensure the best performance of repairable systems. This paper considers how to reduce system maintenance cost while ensuring consistent system performance. Due to budget constraints, preventive maintenance (PM) can be done on only some of the system components. Also, different selections of components to be maintained can have markedly different effects on system performance. On the basis of the above issues, this paper proposes an importance-based maintenance priority (IBMP) model to guide the selection of PM components. Then the model is extended to find the degree of correlation between two components to be maintained and a joint importance-based maintenance priority (JIBMP) model to guide the selection of opportunistic maintenance (OM) components is proposed. Also, optimization strategies under various conditions are proposed. Finally, a case of 2H2E architecture is used to demonstrate the proposed method. The results show that generators in the 2E layout have the highest maintenance priority, which further explains the difference in the importance of each component in PM.

3

Opportunistic maintenance strategy of a Heave Compensation System for expected performance degradation

Zhang Chao, Qian Yujie, Dui Hongyan, Wang Shaoping, Chen Rentong, Tomovic Mileta M.

Eksploatacja i Niezawodność

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2021

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Vol. 23, no. 3

512--521

EN

In the marine industry, heave compensation systems are applied to marine equipment to compensate for the adverse effects of waves and the hydraulic system is usually used as the power system of heave compensation systems. This article introduces importance theory to the opportunistic maintenance (OM) strategy to provide guidance for the maintenance of heave compensation systems. The working principle of a semi-active heave compensation system and the specific working states of its hydraulic components are also first explained. Opportunistic maintenance is applied to the semi-active heave compensation system. Moreover, the joint integrated importance measure (JIIM) between different components at different moments is analyzed and used as the basis for the selection of components on which to perform PM, with the ultimate goal of delaying the degradation of the expected performance of the system. Finally, compared with conditional marginal reliability importance (CMRI)based OM, the effectiveness of JIIM-based OM is verified by the Monte Carlo method.

4

Degradation modeling method for rotary lip seal based on failure mechanism analysis and stochastic process

Liu Di, Wang Shaoping, Tomovic Mileta M.

Eksploatacja i Niezawodność

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2020

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Vol. 22, no. 3

381--390

EN

Rotary lip seal is widely used in aircraft and its performance affects the safety of the aircraft. Hence, it is necessary to estimate useful lifetime and reliability of the seal. Degradation of rotary lip seal is always with random effects, which cannot be considered by theoretical failure mechanism analysis. Hence, in order to consider the random effects of rotary lip seal degradation, stochastic processes are applied. Furthermore, considering the monotonic degradation of the seal, Gamma process and inverse Gaussian process are selected as the candidate processes. To combine the candidate processes, Bayesian model averaging is introduced. Based on the failure mechanism analysis and numerical simulation, the theoretical wear path is predicted and corresponding linearization method is proposed. The measured degradation data is converted and the seal wear process is transformed to a linear degradation process. The model parameters and model probabilities are evaluated by fully Bayesian inference method. The effectiveness of the proposed method is verified by comparing the predicting degradation and experimental observations. The proposed method can be used to evaluate reliability and useful lifetime of rotary lip seal. According to sensitivity analysis, an effective way to improve lifetime and reliability of the seal is to increase the wear depth threshold.

PL

Obrotowe uszczelnienia wargowe znajdują szerokie zastosowanie w samolotach, a ich sprawność wpływa na bezpieczeństwo statków powietrznych. Oznacza to, iż szacowanie żywotności i niezawodności tego rodzaju uszczelnień ma kluczowe znaczenie. Degradacja obrotowego uszczelnienia wargowego jest zawsze związana z efektami losowymi, których nie uwzględnia teoretyczna analiza mechanizmu uszkodzenia. Dlatego też do oceny efektów losowych degradacji obrotowego uszczelnienia wargowego wykorzystuje się procesy stochastyczne, takie jak proces Gamma czy odwrotny proces Gaussa. W przedstawionej pracy, wybrane procesy degradacji łączono za pomocą metody bayesowskiego uśredniania modeli. Na podstawie analizy mechanizmów uszkodzeń i symulacji numerycznej, konwertowano uzyskane w pomiarach dane degradacyjne, co pozwoliło na przekształcenie procesu degradacji obrotowego uszczelnienia wargowego w proces liniowy. Parametry modelu i prawdopodobieństwa oceniano za pomocą metody pełnego wnioskowania bayesowskiego na podstawie obserwacji degradacji. Skuteczność przedstawionej metody weryfikowano porównując przewidywane i obserwowane wartości degradacji. Proponowaną metodę można wykorzystywać do oceny niezawodności i żywotności obrotowego uszczelnienia wargowego. Przeprowadzona analiza czułości pokazuje, że skutecznym sposobem na poprawę żywotności i niezawodności omawianego typu uszczelnienia jest zwiększenie progu uszkodzenia w postaci maksymalnej głębokości zużycia.