Available Analyses for Simulation Diagrams

Repairable system analysis via simulation focuses on maintainability/availability analysis. Additional related analyses made possible by using simulation include throughput analysis and life cycle cost analysis.

Results relevant to these analyses are available in several different locations:

• The Results Explorer provides a comprehensive set of metrics on the system, blocks, crews and spare part pools, including results relevant to maintainability/availability, costs and throughput.
• The simulation Quick Calculation Pad (QCP) provides quick access to some of the most frequently requested reliability results. These include mean and point availability/unavailability, point reliability/probability of failure, mean time to first failure and time at which a certain availability or reliability will be shown.
• A wide variety of plots help you to visualize the simulation results. These include plots pertaining to the system, blocks, crews and spare part pools, offering information about maintainability/availability, costs, throughput and resource utilization.

Maintainability/Availability Analysis

Maintainability is defined as the probability of performing a successful repair action within a given time. In other words, maintainability measures the ease and speed with which a system can be restored to operational status after a failure occurs. For example, if it is said that a particular component has a 90% maintainability in one hour, this means that there is a 90% probability that the component will be repaired within an hour. In maintainability, the random variable is time-to-repair, in the same manner as time-to-failure is the random variable in reliability.

Availability is a performance criterion for repairable systems that accounts for both the reliability and maintainability properties of a component or system. It is defined as the probability that the system is operating properly when it is requested for use. That is, availability is the probability that a system is not failed or undergoing a repair action when it needs to be used.

The ReliaWiki resource portal has more information on maintainability/availability analysis at: http://www.reliawiki.org/index.php/Introduction_to_Repairable_Systems.

Throughput Analysis

Throughput is the amount of output that can be processed in a given period of time. Please refer to the Throughput Analysis topic for more information.

Life Cycle Cost Analysis

A life cycle cost analysis examines the costs incurred by a system or a component over its entire life span. Typical costs for a system may include:

• Acquisition costs (or design and development costs).
• Operating costs:
  • Cost of failures (e.g., contractually-specified penalties, risk of damage to equipment or people, etc.).
  • Cost of repairs.
  • Cost for spares.
  • Downtime costs (e.g., contractually-specified restitution).
  • Loss of production.
• Disposal costs.

A complete life cycle cost (LCC) analysis may also include other costs (such as the initial costs of land, equipment and/or installation), as well as other accounting/financial elements (such as discount rates, interest rates, depreciation, present value of money, etc.). With respect to the cost inputs for such an analysis, the costs involved are either deterministic (such as acquisition costs, disposal costs, etc.) or probabilistic (such as cost of failures, repairs, spares, downtime, etc.). Most of the probabilistic costs are directly related to the reliability and maintainability characteristics of the system. To perform life cycle cost analysis in BlockSim, you will need to provide cost information in all relevant fields. Additional inputs relating to downtime may also be required, depending on your system. The ReliaWiki resource portal has more information on life cycle cost analysis at: http://www.reliawiki.org/index.php/Additional_Analyses#Life_Cycle_Cost_Analysis.