Main types of failure laws

Model 1: Exponential distribution, λ is considered to be a constant

Exponentielle

Corresponds to a Weibull distribution for which parameter β = 1

Model 2: Normal distribution – the failure appears around a t mean

lognormale

Corresponds to a Weibull distribution for which parameter β = 3.6

Model 3: Log-normal distribution – applies to the phenomena of mechanical wear/use

Normale

Corresponds to a Weibull distribution for which parameter β = 2.5