Demand load calculation

[Robbie]

I'm trying to analyse a system which has a unit subject to repeated demands (e.g. 12/week), for a limited time (less than an hour). I want to compare an option where I use 2 units to meet the requirement, instead of one - any thoughts on how to do this. I have a calculated a MTBF in terms of demand and and probability of failure on demand and understand how to do this for 1 unit - increasing the number of units to meet the requirement, I'm not so sure. Can I use weibull++ for this?

[Arai.M]

Hello Robbie,
What you describe is more of a load sharing situation. Weibull++ does not solve this kind of problem. The following links may steer you in the right direction, http://www.weibull.com/hotwire/issue81/hottopics81.htm (http://www.weibull.com/hotwire/issue81/hottopics81.htm), http://www.weibull.com/SystemRelWeb/load_sharing.htm (http://www.weibull.com/SystemRelWeb/load_sharing.htm). They use ALTA for parameter determination (which seems you have looked into by getting an MTBF as a function of demand) followed by an RBD analysis.
Regards,
Arai