Simulation Diagrams

In contrast to analytical diagrams, simulation diagrams can take into account repair and restoration actions, including behaviors of crews, spare part pools, throughput, etc. These actions mean that the age of system components is no longer uniform nor is the operation time of the system continuous. If one includes information on the repair and maintenance characteristics of the components and resources available in the system, other information can also be analyzed/obtained, such as system availability, throughput, spare parts utilization, life cycle costs etc. This can be accomplished through discrete event simulation.

In simulation, random failure times are generated from each component's failure distribution. These failure times are then considered in accordance with the way the components are reliability-wise arranged within the system. The overall results are analyzed in order to determine the behavior of the entire system.

The advantages of the simulation approach are:

It can be used for highly complex scenarios involving a multitude of probabilistic events, such as corrective maintenance, preventive maintenance, inspections, imperfect repairs, crew response times, spare part availability, etc. When events such as these are considered, analytical solutions may become impossible when dealing with complex systems.
Discrete event simulation also has the capability of:
- Examining resource utilization, efficiency and costs.
- Optimizing procedures and resource allocation.
- Analyzing relationships between systems and components.
- Maximizing throughput.
- Minimizing work downtimes.

The disadvantages of the simulation approach are:

It can be time-consuming.
The results are dependent on the number of simulations.
There is a lack of repeatability in the results due to the random nature of data generation.

For these reasons, if your scenario and/or results of interest do not require you to use a simulation diagram, it is recommended that you use an analytical diagram.