Condition Based Maintenance CBM

[Ali]

I'm trying to model a machine with two sensors, one measures pressure and the other measures vibration.

the machine failure rate depends on those values that we need to monitor. lets say that both measures are function of time.

X(t)= Pressure

Y(t)= Temp.

the failure rate will be a function of x and y and we want to trigger the maintenance if the conditional failure probability exceeds the threshold.

any idea or hints on how to model this in simio?

~Ali

[dsturrock]

1) Start by representing your Pressure and Temp as States of type Level (see Definitions > States). These state values can continuously change based on the value of a rate. Setting that rate to +, - or 0 is something you can do wherever appropriate in your model. (Example: have a state named Pressure, and assign Pressure.Rate to its rate of change based on what causes it to rise or fall).

2) Create a Monitor for each State (Definitions > Elements) of Type CrossingStateChange with an appropriate Initial Threshold Value. When the value of the state being monitored crosses the threshol value, it automatically triggers an event named MonitorName.Event. (Example: have a Monitor named PressureExceeded and set its threshold at a maximum pressure allowed (e.g. 250))

3) If you just had a single monitor, then on a Server you could specify reliability logic with a failure of type Event Count Based and use the event from that monitor (Example: Fail each time PressureExceeded.Event occurs).

You don't say if you intend to use a Server or a custom machine. The basic approach above will work in either case. But to deal with multiple sensors might require some custom processes or a custom object because the Server is designed to deal with only one failure stream. There are several ways of approaching multiple failure streams depending on your objectives.

Here is a simple model in 5.81 to illustrate:ServerFailsBasedOnSensor.spfx

[Ali]

Thanks Dave for your example, however, we want to trigger the maintenance based on the failure probability of the machine not based on the pressure value. the failure probability if a function of (x,Y).

let say that:

Pressure = X(t)= kt, t= processing time, k=constant

Temp= Y(t)= sin(t)+6t

Failure Pr.= P(X,Y)

Po= 0.75. >> threshold

if Pr(X,Y)=> 0.75 stop the machine.

my first thought was to model those two measures as resources put then I couldn't figure out a way to link that with the reliability logic