Simulation fields for Failure Cause

Simulation Fields for Failure Cause

Data that can be filled in for a failure cause is described in "Failure Cause". The fields below are discussed with respect to their role in simulation.

Failure mode

The failure mode is the way in which condition loss occurs. Your selection here is between usage-based and time-based

MTTF

MTTF (Mean Time To Failure) is the average time that goes by before an object will have a failure without any maintenance.

Distribution and Deviation

• Normal distribution = Average value and deviation

• Exponential distribution = Average value

• Weibull distribution = Average value, deviation and minimum life span

• Log-normal distribution = Average value and deviation

• Fixed = Average value

Function loss

You can use the Function Loss option to indicate the function loss percentage when an object fails, because this affects the downtime reporting.

The value indicates how much relative loss of function failure will cause. This field only influences calculation if the underlying maintenance action has its 'Downtime' set to 'No Effect' or 'Out of service'.

The initial value of this field is 0%, meaning no function loss. To indicate function loss, a number between 0 and 100 (full function loss) needs to be entered.

When setting a function loss of 75%, this percentage will be incorporated into the downtime. A 4-hour downtime with a 75% function loss will then result in 3 hours downtime in the report

Hidden

By default, failures are resolved immediately by performing the (mandatory) FBM action. But by checking Hidden, a failure will not be detected, and no failure-dependent maintenance action will be initiated. Especially with safety and backup systems, it often occurs that failures are not spotted.

An example is the breakdown of the engine oil warning light in a car. When such an object fails, it is not a matter of course that an FBM action will be initiated. Selecting this option allows you to model this condition.

When this option is checked and the failure leads to a 100% downtime, this means that the entire serial section to which the failure belongs, will be shut down. This section will not come "up" until the failure has been resolved by a preventive maintenance action. In general, such a condition does not occur in availability calculations (these failures are detected immediately), but it does occur in safety calculation models.