reliability maintenance engineering 2 - 1 concepts and software
DESCRIPTION
Reliability Maintenance Engineering Day 2 session 1 Concepts and Software Three day live course focused on reliability engineering for maintenance programs. Introductory material and discussion ranging from basic tools and techniques for data analysis to considerations when building or improving a program.TRANSCRIPT
Reliability Engineering
Fred [email protected]
FAULT TREES & BLOCK DIAGRAMSDay 2 Session 1
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
Discovery of Risks
• What could go wrong?
• What has gone wrong?
• Analysis
• Testing
Analysis
• FMEA
• What if
• Modeling
• Expert opinion
Hazard Analysis
• Plot severity and occurrence
• Local policy on priorities
Likelihood of Occurrence
Seve
rity
Identification in not enough
• Experiments
• Design
• Constrain
• Mitigate
Discussion & Questions
Fault Tree Analysis
Deductive analysis process
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
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
RBD Construction
• Series • Parallel
A
B
A B
Discussion & Questions
Simulation
• Build RBD
• Run simulation– 100 days– 100 cycles– What if analysis
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?
Blocksim Simulation
Discussion & Questions
Policies
• Rules to govern repair and maintenance tasks
• Inspections• Crews• PM and CM tasks
Block Diagram
Which relays are most important availability wise?
Importance Plot
Spares planning
Discussion & Questions
Monty Carlo Methods
• Failure mechanism models
• Empirical models
• Use stress and environment models
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 / 4Area of Square
Example
• 30 known failure mechanisms
• Distribution of use and environmental stresses
• Models to predict failures
Outputs
Time
Prob
abili
ty o
f Fai
lure
Discussion & Questions
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