The ALT module supports many life stress models for analyzing ALT data sets. While they all support constant stress analysis, only three models support time-varying stress analysis: Arrhenius, Eyring, and Inverse Power Law. For time-varying stress analysis, stress typically increases over time. For each stress to analyze, in the Stress Model window, you select a stress profile that specifies how it increases. In the Default Stress Profile column that is made available for this purpose, you can select from all stress profiles inserted in the System file. For more information, see Stress Profiles.

The following table indicates the number of stresses required by life stress models as well as minimum failure requirements for successful calculations. When you click OK in the Stress Model window, stress data is validated to ensure that the appropriate number of stresses are active. For more information, see Stress Data Validation. When the data set is calculated, a check is performed to verify that there are no blank values and that it contains the minimum number of failures required by the model. You can view results for a data set under Calculation results in its ALT Parameters pane. For more information, see Life Stress Model Parameters.