1. Chapter 4 Supplement Reliability 1Saba Bahouth – UCO

2. 2 Reliability: the probability that a manufactured good, piece of equipment, or system performs its intended function for a stated period of time under specified operating conditions. Several ways to looking at reliability: First view: Related to the probability of working properly when needed. Second view: Related to the life of the product (How long does it work before it breaks) Probability of a product serving longer than a specified period of time

3. R P = 0.98 R L = 0.95 R F = 0.97 3Saba Bahouth – UCO

4. Example of Overhead Projector R P = 0.98 R L = 0.95 R F = 0.97 R bL = 0.96 R s = 0.94 4Saba Bahouth – UCO

5. Probability of first component working + Probability of second component working x Probability of needing second component R ss = R ss = R m + { (1-R m ) x R b } Providing Backups 5Saba Bahouth – UCO

6. Average Reliability of all Components (Percent) Reliability of the System (Percent) 100 80 60 40 20 0 100 99 98 97 96 n=1 n=10 n=50 n=100 n=200 n=300 n=400 System Reliability - Components in Series 6Saba Bahouth – UCO

7. Basic Rule.90.80.70 1-[(1-.90)*(1-.80)*(1-.70)] =.994 1 – P(all fail) Lamp 1 Lamp 2 (backup for Lamp1) Lamp 3 (backup for Lamp 2) 7Saba Bahouth – UCO

8. Availability The fraction of time a piece of equipment is expected to be available for operation. MTBF = mean time between failures MTR = mean time to repair 8Saba Bahouth – UCO

9. Infant mortality Regular failureWear-out failure Failure rate Lifetime 9Saba Bahouth – UCO

10. Improving Reliability Component design Production/assembly techniques Testing Redundancy/backups Preventive maintenance procedures User education System design 10Saba Bahouth – UCO

11. Exponential Distribution Reliability = e -T/MTBF 1- e -T/MTBF TTime 11Saba Bahouth – UCO

12. Normal Distribution Reliability 0z 12Saba Bahouth – UCO