The Bathtub Curve

It is claimed to represent the failure rate of a population of components systems.

The bathtub curve. The bathtub curve captures a higher but decreasing rate of failure at the beginning of the product lifetime due to manufacturing defects a lower failure rate throughout most of the usable. The first part is a decreasing failure rate known as early failures. 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.

This is the well known bathtub curve which over the years has become widely accepted by the reliability community. The bathtub curve named for its shape and shown in fig. Universally accepted by systems engineers conducting lifecycle management in products in all industries this visual representation describes failure probability across three phases. The bathtub curve is often quoted in texts about maintenance.

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. A form of the hazard function used in reliability testing that captures three phases of failure rates that are observed in some products. The curve has three parts to it. As can be seen from the picture above the bathtub curve.

Posted on august 31 2011 by seymour morris. Figure 1 shows a typical time versus failure rate curve for equipment. Instead the curve describes the relative failure rate of an entire population of products over time. An infant mortality period with a decreasing failure rate followed by a normal life period also known as useful life with a low relatively constant failure rate and concluding with a wear out period that exhibits an increasing failure rate.

The second part is a constant failure rate known as random failures. 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. Useful life or normal life with almost a constant low failure rate. Perhaps a useful place to start is with a look at the bathtub curve.

The first downward portion of the curve is called an infant mortality phase and shows how. The third part is an increasing failure rate known as wear out failures. Bathtub curve is a graphical representation of the failure rate for a population of products and not for only 1 product over time. The bathtub curve is a type of model demonstrating the likely failure rates of technologies and products.

Infant mortality or early failures having a decreasing failure rate.