Weibull++'s Accelerated Life Testing module allows users to perform a degradation analysis using the linear, exponential, power, logarithmic, Gompertz and Lloyd-Lipow models. The equations for these models are listed below:
- Linear: y = a·x+b
- Exponential: y = b·ea·x
- Power: y = b·xa
- Logarithmic: y = a·ln(x)+b
- Gompertz: y = a+bc·x
- Lloyd-Lipow: y = a-b/x
where y is the degradation measurement, x is the inspection time and a, b and c are model parameters.
These models can be used to predict when the degradation of a given unit will reach the predefined failure level. The predicted time can then be treated as the failure time. Once the model parameters are estimated for each test sample, xi can be extrapolated using the defined critical value of y. The computed xis from all the units can then be used as failure times for subsequent accelerated life data analysis.