RG Models Used in TFT
? Crow-AMSAA
? Duane
? Gompertz and Modified Gompertz
? Lloyd Lipow
? Logistic
Duane Model
? Also called as “Duane Postulate”.
? Developed based on an observation by J.T. Duane.
? Duane observed that the cumulative failure rate vs
cumulative test time was linear on a log-log paper
when he plotted test data from generators, hydromechanical
devices and aircraft engines.
? It is a deterministic model.
? Used for Test-Fix-Test data.
? MTBFC is cumulative=total failures/total time.
? MTBF0 is at starting point.
? T0 is starting time and is the growth rate.
? Can be used to estimate required test time to reach
goals or if time is fixed, determine how many systems
must be tested .
? With good effort ~0.3-0.4 for complex systems.
? Instantaneous MTBFi=MTBF/(1- ).
Growth.pdf
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