jmvalks
Newbie level 5
I have a system consisting of 4 identical components. The components are independent so that the probability of failure of each component is independent of the other.
I have a failure rate, lambda, of 4.60994 /10^6 hours.
I need to calculate the MTBF of the system assuming that 75% of the components must be operational, otherwise the system has failed. So 3 out of the 4 components must be operational.
I have been given a figure in the document I am working with of 4.8028x10^13 hours.
I have tried using a binomial distribution using the given failure rate and time (or mission length) t of 360 hours.
So the the exponentials in the binomial expansion become exp^(-lambda * t * i) and (1 - exp(^-lambda * t))^(4-k),
with k from 3 to 4.
I then take
1 - result to give the failure rate, F, which I then convert to MTBF as 1/F.
I cannot arrive anywhere near this figure. The best I have is 60748 hours.
Can anyone give me some guidance?
Thanks
JV
I have a failure rate, lambda, of 4.60994 /10^6 hours.
I need to calculate the MTBF of the system assuming that 75% of the components must be operational, otherwise the system has failed. So 3 out of the 4 components must be operational.
I have been given a figure in the document I am working with of 4.8028x10^13 hours.
I have tried using a binomial distribution using the given failure rate and time (or mission length) t of 360 hours.
So the the exponentials in the binomial expansion become exp^(-lambda * t * i) and (1 - exp(^-lambda * t))^(4-k),
with k from 3 to 4.
I then take
1 - result to give the failure rate, F, which I then convert to MTBF as 1/F.
I cannot arrive anywhere near this figure. The best I have is 60748 hours.
Can anyone give me some guidance?
Thanks
JV
