Life-Stress Plots

Life vs. stress plots and probability plots are the most important plot types in accelerated life testing analysis. Life vs. stress plots are widely used for estimating the parameters of life-stress relationships. Any life measure can be plotted versus stress in the life vs. stress plots available in ALTA. Confidence bounds information on each life measure can also be plotted. The most widely used life vs. stress plots are the Arrhenius and the inverse power law plots. Figure 7 illustrates a typical Arrhenius life vs. stress plot.

Fig. 7: Typical Arrhenius Life vs. Stress plot

Each line in Figure 7 represents the path for extrapolating a life measure, such as a percentile, from one stress level to another. The slope and intercept of those lines are the parameters of the life-stress relationship (whenever the relationship can be linearized). The imposed pdfs represent the distribution of the data at each stress level.