Reliability/Unreliability Plots

There are two types of reliability plots. The first type is a 2-dimensional plot of reliability vs. time for a given stress level. The second type is a 3-dimensional plot of the reliability vs. time vs. stress. The 2-dimensional plot of reliability is just a section of the 3-dimensional plot at the desired stress level, as illustrated in Figure 2.

Fig. 2: Example of the relationship between 3D and 2D reliability plots.

A reliability vs. time plot provides reliability values at a given time and time at a given reliability. These can be plotted with or without confidence bounds. The same 2-dimensional and 3-dimensional plots are available for unreliability as well and they are just the complent of the reliability plots.