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This page is under development and will during the spring and summer of 2014 be subject to many changes.

TPK 5170 RAMS Assessment and Optimization

...adds new methods to your RAMS toolbox and new skills in the application of these.

 

Brief background of course

This course is the specialization course in reliability, availability, maintenance and safety (RAMS) in the last fall semester of the (2 year) international master program in RAMS and the (5 year) master program in Mechanical Engineering (in Norwegian: Produktdesign og Produksjon - PUP).

The course aims to build new knowledge and new skills in RAMS methods. In some cases, this means to extend the application of lectured methods and models, while in other cases, it means to introduce new methods to broaden the perspective to how RAMS assessments may be carried out.

The course belongs to the large envelope of RAMS courses given from the department of Production and Quality Engineering at NTNU.  The course is adminstred by the RAMS group at this department. It is expected that the students already have taken (or have relevant background corresponding to):

  • TPK 4120: Safety and Reliability
  • TPK 4140: Maintenance Management 
  • TPK 5160: Risk Analysis 

This course replaces the earlier arrangement with two specialization modules in RAMS, one in risk and reliability and one in maintenance optimization (each with 3.75 credit points). This means that TPK 5170 includes some subjects from both areas: risik and reliability and maintenance optimization, and gives 7.5 credits (i.e., as a regular course normally does at NTNU).

  • You may ask why this is necessary, if the you (for example) are focusing mainly on risk analysis in the specialization project and master thesis. The answer is rather simple: This course should give you the remaining topics that we - as a RAMS group - think you should have when you leave NTNU with a specialization in RAMS.

It may be remarked that this course may, from the fall of 2015, change the name to "Asset management methods". A new course in "Reliability of safety-critical systems" ("SIS course") will at the same time be introduced (from spring 2015). Topics related to  reliability assessment will be transferred to the new ("SIS") course, and it is planned that TPK 5170 with its new profile will expand on topics related to maintenance optimization and the estimation of remaining useful life. The changes will be available http://www.ntnu.edu/studies/courses, once implemented.

The responsible person for TPK 5170 in the fall of 2014 is Professor Mary Ann Lundteigen. She will give approximately 50% of the lectures. Since this is a specialization course, some "specialists" are brought in for specific topics. For example, Associate Professor Yiliu Liu  will lecture methods like PetriNets. Lectures that belong to the topic maintenance optimization are planned to be lectures by our new Professor Anne Barros.

Course objective and motivation

The main objective of this course is to increase the depth of understanding about RAMS assessment. Sometimes the purpose of the assessment is to determine the reliability requirements or to determine the reliability of system functions in light of safety requirements. At other times, the purpose is to minimize costs or downtime of the systems, by considering different maintenance strategies.

Think about a system. This system may constitute many different parts and together they shall perform many different functions. Systems may be production-critical, safety-critical, or even both. Safety-critical systems are used to protect personnel from injury and death, or to protect the environment from severe damages.  Production-critical systems may, if they fail, cost "a whole lot", and have a severe effect on a manufacturer reputation, the quality of products developed, and the costs associated with correcting the system after failure. Critical infrastructures may be consideres as both production and safety-critical. Stable and safe public transportation, clean and stable water supply, power supply, and net supply are important for serving the society and business, and a failure of these could affect safety at a local level as well as at a national level.

Some key questions to ask in relation to such systems are shown in the figure below, and in many cases, they need to be solved using RAMS assessment and optimization methods.

This means that methods already introduced in other courses are studied in more detail, with assistance of new application examples and new perspectives. Some new methods are also introduced so that the students, after having taken the course, will have a heavy weighted toolbox of methods to use in their future work tasks.  

Expected learning outcome

 

Knowledge:
Obtain a more thorough understanding of the theoretical foundation and the practical applications of RAMS assessment and optimization methods. 

Skills:
Being able to identify suitable frameworks, methods, and software and to use these to solve RAMS assessment and optimization tasks.

General competence:
Understand RAMS as an important cornerstone of industrial and commercial systems and in the public administration. 

 

Industry relevance

Reliability assessments of safety-critical systems are key services provided by many consultancy companies, such as with Safetec, Lloyd's Register Consulting, and DNV-GL (link to the GL-part of the services), and Lilleaker Consulting. Manufacturers like ABB, Siemens, AkerSolutions, FMC, Kongsberg Maritime and many others need to design systems in light of reliability requirements, and also demonstrate (sometimes with assistance of the consultancy companies) that the reliability requirements are met. End users, like railway service providers like Jernbaneverket, oil companies like Statoil, Det Norske, GDF-Suez, Shell and Conoco-Phillips, and Wintershall and other industries like smelting plants and water power suppliers must be competent to select proper system design, follow up the system performance and select the most suitable maintenance strategies to keep costs and safety within the accpetable limits.

Topics covered

Topics to be covered are as part of the course are (organized according to whether the application is mainly for safety-critical systems or production-critical systms, or both) presented below. Note that more than one lecture may be used to cover one particular topic. See the lecture plan for more details.

Reliability analyses of safety-critical systems

 

  • Development of reliability requirements

    "Safety integrity level (SIL) is a key reliability performance measure used for safety-critical systems. Reliability requirements are therefore often given as SIL requirements are identified in an extension of the risk analysis, using methods often refered to as SIL allocation, SIL targeting and SIL classification. Key methods like Layers of protection analysis (LOPA), risk graph, and minimum SIL are presented and discussed."
  • Reliability analyses: Extending with new analytical & dynamic modeling approaches.

    "In TPK 4120, some analytical formulas were introduced to calculate the average probability of failure on demand (PFD). It was also shown how the average PFD may be calculated using Markov methods and fault tree analysis. This reliability measure is of high importance in relation to SIL, as a relationship is established between a SIL requirement and the maximum PFD tolerated for a safety function. In this course, we go a step further and introduce the foundations for analytical formulas presented in IEC 61508 (a key standard for reliability of safety-critical systems), the PDS method (a method along with a set of analytical formulas widely adapted in the Norwegian oil and gas industry, but which has a wider application area), and dynamic modeling, using Petri Nets."

  • Special analysis challenges (possible candidates for under this heading):
    • Partial and imperfect testing
    • Follow-up of SIL requirements in the operational phase
    • Hardware fault tolerance - Hardware design constraints of safety-critical functions

 

Maintenance optimization

  

  • Age, block and minimal repair strategies.

The intervals of maintenance for safety-critical systems are normally determined from the reliability analyses. For other systems, we may use decide upon intervals of testing using different maintenance strategies. These models include parameters like costs, failure rates, and aging. The models come of with the answer to the following two questions: When should we do maintenance and what tasks and equipment should be included. The application of these methods are many. Two examples are maintenance planning of railway tracks and another is planning of intervention (for maintenance purposes) of subsea equipment.

Sub-topics also covered under the same "umbrella" are:

    • Modeling of effective failure rate:
      Maintenance interval and and intervention level (extensiveness of maintenance) is obviously influencing the failure rate of the components. This topic concerns the modeling of the relationship between these two parameters and what we can refer to as the effective (or resulting) failure rate.
    • Weibull renewal:
      **Say something here** 
    • PF models and state based models:
      **Say something here** 
  •  Spare part optimization:

Spare parts may be costly to have on the stock, but at the same time it is costly not to have a spare part available when it is needed. This topic concern how to calculate the probability of running out of spares, using simple formulas and Markov analyses. The use of Monte-carlo simulations for this purpose is also shown. This topic may not be some relevant for very specialized systems, where it is not possible to aquire a spare within short time. For a manufacturer that develops products, such as sensors, in a large scale to e.g. the oil and gas industry, it may be relevant to find the optimal number of spare parts for warranty and repair services. 

 

  •  Prognostics and remaining useful life:
    **Say something here**
  • Bayesian methods
  • Counting processes

 

Tutorials & Project

There will be mandatory problems/tasks to solve as part of the course.

TopicProblems Software
Reliability assessmentProblems will be selected from the following booklet Matlab, Maple, Grif
Maintenance optimization Problems will be .... Excel


Software Matlab, Maple and Grif (the latter is a rather recent software for reliability assessment in use here at the NTNU) will be preferred to assist the reliability analyses.

 

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