Chapter 12 Maintainability and Availability
12.1 introduction Availability analysis of the system requires a knowledge: (1)How the components are functional connected. (2)The failure process of the component. (3)The method of operation and the definition of the failure. (4)The repair or maintenance police.
12.2 Maintainability Concept Maintainability M(t) : the probability of repairing a failed component or system in a specified period of time. Two kinds: Preventive maintainability Corrective maintainability
Preventive maintainability reliability of the system
System Reliability
Example 12.2 derive the condition under preventive maintenance is beneficial to the
imperfect maintenance
Repair time distribution
Unrepaired failure Number of unrepaired failure in time
Optimum replacement strategy The total number of the times the component is replaced is given by
Spare parts requirement The probability of having n failure in time t :
Example 12.9 Three kind of component in an system : 20 in type A (failure rate 0.002), 130 in type B (failure rate ), and 100 in type C (failure rate ). Find the number of spare parts required to cover the mission period 30 days and 99 percent of probability
12.3 Availability definition
3. Steady state availability 4. Inherent availability 5.Achieved availability 6.Operational availability
Availability Analysis Development of model
system with single component
Series system One repair person :
Two repairperson
Parallel system
One repair person
Two repair persons
12.4 Optimization Approach