Calculation Determination
When RBD calculations run, the configuration of the block diagram is analyzed to determine if standard analytical methods can be used to compute system reliability and availability. If system reliability and availability can be calculated analytically, analytical methods are used to perform these computations.
Monte Carlo simulation is used to calculate system reliability and availability in two cases:
• If the configuration is too complex for system reliability and availability to be calculated using standard analytical methods.
• If you have indicated that Monte Carlo simulation is to be forced.
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Selecting Force Monte Carlo simulation on the Advanced page in the RBD calculation properties forces simulation to be used, even if calculating system reliability and availability analytically is possible. For more information, see Advanced Page.
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While the default number of iterations is 1000, on the Advanced page in the RBD calculation properties, you can specify the number of iterations to perform. The results of the Monte Carlo simulation are the results found during this series of simulations. As a general rule, the more iterations performed, the more accurate the results become.
During a Monte Carlo simulation, the specified number of iterations are performed to gather data regarding system successes and failures. Each iteration is a test that runs through the system from the start node through the end node to determine whether the system completes its task or fails. During the iteration, the calculation properties of each block are used to decide whether the block is operating or not, which then is used to determine if the system is operating. For each iteration, the number of successful states is tracked. Comprehensive information about the methodology appears in RBD Simulation Methodology.