Load Life Models
As described in Redundancy Page, for Redundancy Type, you can select Load Sharing. When you select this type, the underlying failure distribution for the block is combined with a load life relationship to model the failure characteristics of the components remaining in operation when one of their fellow load-sharing components fails. The load life relationship describes how the specific life characteristic for the block’s underlying failure distribution changes with the application of an increased load on the remaining load-sharing components.
The table below shows the parameter values and life characteristic value for the three most commonly used failure distributions. For example, when the Weibull distribution is selected, the scale parameter, η, is the life characteristic that is assumed to be stress-dependent while β is assumed to remain constant.
Distribution
Parameters
Life Characteristic
Weibull
β
Scale parameter, η
Exponential
λ
Mean life (1/λ)
Lognormal
Median,
β and σ are usually assumed to be constant.1
The following topics provide equations for load life models: