Event Modeling

Relyence Fault Tree supports various input models for accurately describing your fault tree events. To select the most appropriate model for your event, click on the event to select it, then dropdown the list for Input Model in the Properties pane. 

Select the appropriate input model for calculating the event probability and other quantitative metrics:

• Asymptotic Unavailability: time-independent, based on an asymptotic unavailability formula
• Constant Mission Time: time-independent, based on a constant mission time
• Constant Probability: time-independent, based on probability and frequency; Frequency specifies the number of Failures that occur per Hour
• Failure Rate: time-dependent, based on an exponential distribution of the Failure Rate or Mean Time to Failure
• Failure Rate (approximate): time-dependent, based on an approximate formula for the exponential distribution of the Failure Rate or Mean Time to Failure
• Failure with Repair: time-dependent, based on an exponential distribution of the Failure Rate or Mean Time to Failure and Mean Time to Repair (MTTR)
• Frequency with Failure Rate: time-dependent, based on an exponential distribution of the Failure Rate or Mean Time to Failure and Frequency; Frequency specifies the number of Failures that occur per unit time based on your Failure Rate Units setting
• Lambda Tau: time-independent, based on the upper bound of unavailability using the Lambda Tau method
• Latent Repairable: time-independent, based on the asymptotic unavailability of a repairable system with latent failures
• Lognormal: time-dependent, based on a lognormal distribution of the Mean Time to Failure
• Mean Unavailability (approximate): time-independent, based on an approximation of average unavailability based on the Lambda Tau method
• Normal: time-dependent, based on a normal distribution of the Mean Time to Failure
• Uniform: time-dependent, based on a uniform distribution of the Mean Time to Failure

Relyence Fault Tree will prompt you for the corresponding data parameters needed based on your Input Model selection.