توصيفگر ها :
سيستم اشتراك بار , فرسايش مداوم , بار تصادفي , مدلسازي قابليت اعتماد , نگهداري پيشگيرانه , نگهداري اصلاحي
چكيده فارسي :
در اين مباحث، روش‌هاي جديد خاصي براي مدلسازي قابليت اعتماد سيستم‌هاي اشتراك بار ارائه شده است.
فرض بر اين است كه اجزاي موجود در سيستم به طور مداوم از طريق افزايش بار فرسايش مي‌شوند.
ارزيابي قابليت اعتماد چنين سيستم‌هايي غالبا با اين واقعيت كه هم بار ورودي و هم خرابي اجزاء به طور پيچيده بر فرسايش اجزاي بقا تاثير مي‌گذارد، پيچيده است.
رويكردهاي پيشنهادي ابتدا با اختصاص زمان خرابي‌هاي قبلي و ورود بارهاي تصادفي و سپس تعيين تعداد اجزاي خراب، اين مشكل را كاهش مي‌دهد.
دو مدل جداگانه با قابليت تحليلي قابليت اعتماد سيستم و هم‌چنين تصميم‌گيري در مورد تعمير و نگهداري سيستم پيشنهاد شده است.
اولي بار ثابت و ديگري تجمعي را در نظر مي‌گيرد و يك مثال عددي هم براي نشان دادن اثر بخشي مدل‌هاي پيشنهادي نشان داده شده است.
چكيده انگليسي :
In the study of engineering systems, it is often assumed that components failures are independent, meaning that the failure of one component does not affect the failure of other components, but in many systems the performance of one component will be affected by the performance of other system components.
Hence, it is more realistic to create models that consider random dependencies between system components.
In the real world, many systems has a share-loading property. In the other words, in a load-sharing system, all components in the system share a common workload, and when a component fails, with a specific set of load-sharing rules, the total load is distributed among the remaining components. In most cases, increasing the load increases the failure rate of the survived components.
Load sharing models have interesting applications in nuclear reactor safety, software reliability, distributed computing, war modeling, geology, and medical science.
There are many other industrial examples of load sharing systems. Depending on the nature of the workload and how the work is divided, each of them has its own characteristics.
Technical systems are often subject to increased wear due to use, age, or accidental shocks, which can lead to component failure and eventual system failure and subsequently, high costs, system unavailability and safety hazards. Therefore, it is essential to develop efficient maintenance strategies that minimize costs while maximizing safety and availability.
One of the topics that is of special importance in the theory of reliability is the issue of possible patterns in the maintenance of systems.
Today, most of the advanced systems and equipments used in human life are repairable, such as cars, airplanes, computers, mobile phones, and so on. In such systems, repairs must be made in the event of a failure.
The main purpose of this type of operation is to maintain the system at the desired level of work and reduce the chance of system failure, because by the occurence of this event, very heavy losses, both human and financial, will be imposed. One of the issues raised in this regard is the issue of preventive maintenance. Preventive maintenance is a well-known policy to maintain systems and prevent unexpected breakdowns and costly disruptions. In contrast to preventive repairs, corrective maintenance is a type of maintenance method in which equipment is repaired after a failure has occurred.
In this thesis, we aim to study some maintenance analysis for load-sharing systems.
In Chapter 2, a generic n-variate Farlie–Gumbel–Morgenstern (FGM) copula function is used for modeling the dependency between the components of a load-sharing 𝑘-out-of-𝑛 system. The reliability modeling of this system is explored and maintenance policy for the considered system subject to hidden failures is proposed.
In Chapter 3, it is assumed that components degrade continuously which is increased by the additive load on it.
The reliability assessment of such systems is done under the two models for load; constant load and constant load.
Next, a preventive maintenance model that simultaneously optimizes the inspection
interval and preventive maintenance threshold is developed
