Bathtub Curve Failure Rate

This is the well known bathtub curve which over the years has become widely accepted by the reliability community.

Bathtub curve failure rate. The second part is a constant failure rate known as random failure. Instead the curve describes the relative failure rate of an entire population of products over time. The second part is a constant failure rate known as random failures. The first downward portion of the curve is called an infant mortality phase and shows how.

The bathtub curve is typically used as a visual model to illustrate the three key periods of product failure rate and not calibrated to depict a graph of the expected behavior for a particular product family. A plot of the failure rate over time for most products yields a curve that looks like a drawing of a bathtub. Reliability bathtub curve review as described in more detail in part one the bathtub curve displayed in figure 1 below does not depict the failure rate of a single item. The bathtub curve displayed in figure 1 above does not depict the failure rate of a single item but describes the relative failure rate of an entire population of products over time.

The bathtub curve named for its shape and shown in fig. The first part is a decreasing failure rate known as early failures. Figure 3 4 shows the bathtub curve of a nonrepairable product in which the first part shows a decreasing failure rate known as early failure. And the third part is an increasing failure rate known as wear out failure in general a product s failure rate is high in the beginning operation because of early failure of components.

If enough units from a given population are observed operating and failing over time it is relatively easy to compute week by week or month by month estimates of the failure rate h t. 15 11 is perhaps the most famous graphical representation in the field of reliability plotted is the failure rate h t versus time the resulting curve describes not only the behavior of engineering components but also the lifetimes of human populations. It has proven to be particularly appropriate for electronic equipment and systems. The bathtub curve is widely used in reliability engineering it describes a particular form of the hazard function which comprises three parts.

Over a certain product lifetime the bathtub curve shows how many units might fail during any given phase of a three part timeline. The third part is an increasing failure rate known as wear out failures. Some individual units will fail relatively early infant mortality failures others we hope most will last until wear out and some will fail during the relatively long period typically called normal life.