Reliability Maintenance Engineering 2 - 1 Concepts and Software
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The document outlines the objectives and methods of reliability engineering, focusing on fault tree analysis and block diagrams to identify and reduce system vulnerabilities. It details the construction of fault trees, reliability block diagrams, and the application of simulation techniques such as Monte Carlo methods to improve decision-making and assess risks. Key topics include analyzing potential failures, implementing hazard analysis, and discussing policies related to maintenance and inspection.
Reliability Maintenance Engineering 2 - 1 Concepts and Software
- 2. FAULT TREES & BLOCK DIAGRAMS Day 2 Session 1
- 3. Objectives • Recognize vulnerabilities in a system and reduce risk • Fault Tree Analysis and Block Diagrams • Using simulation to improve decision making • Using simulation options (policies, pools & resources) • Combining life distributions with life stress relationships
- 5. Discovery of Risks • What could go wrong? • What has gone wrong? • Analysis • Testing
- 6. Analysis • FMEA • What if • Modeling • Expert opinion
- 7. Hazard Analysis • Plot severity and occurrence • Local policy on priorities Likelihood of Occurrence Severity
- 8. Identification in not enough • Experiments • Design • Constrain • Mitigate
- 11. Fault Tree Analysis Deductive analysis process
- 12. FTA Construction 1. Define the fault condition, and write down the top level failure. 2. Using technical information and professional judgments, determine the possible reasons for the failure to occur. 3. Continue to break down each element with additional gates to lower levels. 4. Finalize and review the complete diagram. The chain can only be terminated in a basic fault: human, hardware or software. 5. If possible, evaluate the probability of occurrence for each of the lowest level elements and calculate the statistical probabilities from the bottom up. What is Fault Tree Analysis, by Simha Pilot, Quality Progress, March 2002
- 13. Reliability Block Diagram • Reliability Block Diagrams (RBDs) are graphical representations of the components of the system and how they are reliability-wise related --Reliasoft.com
- 14. RBD Construction • Series • Parallel A B A B
- 17. Simulation • Build RBD • Run simulation – 100 days – 100 cycles – What if analysis
- 18. Blocksim Simulation • An airline does annual inspections of vests • Replace faulty vests only • Vests fail with Weibull distribution – beta 2.55 and eta 6.89 years • Should we change the inspection interval?
- 23. Policies • Rules to govern repair and maintenance tasks • Inspections • Crews • PM and CM tasks
- 24. Block Diagram Which relays are most important availability wise?
- 25. Importance Plot
- 26. Spares planning
- 29. Monty Carlo Methods • Failure mechanism models • Empirical models • Use stress and environment models
- 30. Monte Carlo 1. Define a domain of possible inputs. 2. Generate inputs randomly from a probability distribution over domain. 3. Perform a deterministic computation on the inputs. 4. Aggregate the results. Area of Circle = π / 4 Area of Square
- 31. Example • 30 known failure mechanisms • Distribution of use and environmental stresses • Models to predict failures
- 34. Summary • Recognize vulnerabilities in a system and reduce risk • Fault Tree Analysis and Block Diagrams • Using simulation to improve decision making • Using simulation options (policies, pools & resources) • Combining life distributions with life stress relationships Fault Trees & Block Diagrams
Editor's Notes
- #5: Recognize vulnerabilities in a system and reduce risk
- #10: Balance between investment and value
- #11: FTA and RBD-
- #16: Balance between investment and value
- #17: Blocksim simulation
- #22: Balance between investment and value
- #23: Simulation options – policies, etc.
- #26: In this analysis, the relays are reliability-wise identical; however, their position within the diagram matters. This is best illustrated by the reliability importance plot shown next. As you can see, a specific relay failure affects the system differently due to its position within the system. Specifically and in order of importance, the greatest impact is if relay 2 or 5 fails, followed by relay 4 or 3 and then by relay 1 or 6.
- #28: Balance between investment and value
- #29: Simulation distributions and environment/assembly variation
- #30: <image of multiple distribution into black box and an output distribution>
- #31: For example, consider a circle inscribed in a unit square. Given that the circle and the square have a ratio of areas that is π/4, the value of π can be approximated using a Monte Carlo method:[3]Draw a square on the ground, then inscribe a circle within it.Uniformly scatter some objects of uniform size (grains of rice or sand) over the square.Count the number of objects inside the circle and the total number of objects.The ratio of the two counts is an estimate of the ratio of the two areas, which is π/4. Multiply the result by 4 to estimate π.
- #34: Balance between investment and value