What is bathtub curve

However, one should not forget that the period with constant failure rate often becomes dominant only after some time t 0 from putting the system into operation. In such cases, the time t in Equation 6 must be replaced by t — t 0.

Note: One must always keep in mind that the mean time between failures, calculated as the reciprocal value of failure rate, has nothing in common with the mean time to failures caused by aging or fatigue.

Failure rate given in catalogs is determined from the period of steady-state operation. They fail after a much shorter time, for example after 10, h, when they enter stage III wear out. Example 1. Assume that you can choose from various devices available in the market. What are the demanded failure rate and the mean time to failure of a suitable device? Assume exponential distribution of the time to failure.

Example 2. Calculate the probability that the ventilator does not fail during the first h after being put into operation. What is the probability of failure during this time? Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution 3. Help us write another book on this subject and reach those readers.

Login to your personal dashboard for more detailed statistics on your publications. Authored by Constantin Volosencu. Sign up. Term of the Day. Best of Techopedia weekly. News and Special Offers occasional. Bathtub Curve. Techopedia Explains Bathtub Curve.

What Does Bathtub Curve Mean? Techopedia Explains Bathtub Curve One function of the bathtub curve is to show the likelihood of initial failure with products. Three different sections of bathtub curve are given below —. Skip to content. Change Language. Related Articles. Table of Contents. Save Article. Improve Article. This long period of a level failure rate is known as the Intrinsic Failure Period also called the Stable Failure Period and the constant failure rate level is called the Intrinsic Failure Rate.

Note that most systems spend most of their lifetimes operating in this flat portion of the bathtub curve Finally, if units from the population remain in use long enough, the failure rate begins to increase as materials wear out and degradation failures occur at an ever increasing rate. This is the Wearout Failure Period.