Discard Policy - Cost per Unit

[Robbie]

I'm trying to undestand calculations for scheduled discard using a calculation of: ([R(t) x Cost of Planned Replacement] + [(1-R(t) x Cost of Corrective Replacement])/R(t) integrated between 0 and T

I know Weibull++ does this calcualtion (costperunit function) and it is described in Smith (Reliability, Maintainability & Risk book), however I would like to understand the bottom line R(t) integrated between 0 and T and how its calculated. What does the result actually give, does anyone have a worked example or a reference to one?

Thanks you
Robbie

[Pantelis]

You ask " I would like to understand the bottom line R(t) integrated between 0 and T and how its calculated. "

I am assuming you do not mean how one perfroms the integration but rather what does it mean. It is the expected operating time of the component (think MTTF).

You can also see a discussion on http://www.weibull.com/SystemRelWeb/preventive_maintenance.htm

[Robbie]

Thanks Pantelis, the link you sent me was very helpful. You said "think MTTF", however Intergating R(t) between 0 and infinity gives MTTF, I guess this calcualtion (integrating between 0 and T), gives a mean which is a function of both MTTF and avearge replacement time, whatever comes first..?

[Pantelis]

Robbie ... glad it was of help.

Pantelis