The Handy Math Answer Book

What is the bathtub curve?

Industrial engineers usually know about the bathtub curve, especially in reference to

an operating or failing unit. In other words, 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 or year-by-year) estimates of the failure rate. The results of

the calculated population failure rates over time produces a graph. Because the shape

of this failure rate curve resembles the end-to-end section of an antique bathtub, it is

widely known as the “bathtub curve.” This type of analysis is usually used in industrial

settings. For example, it can describe the expected failure rate of certain electronics

over time: initially high; then dropping to 0 failures for most of the system’s lifetime;

then rising again to the other end of the “tub” as the electronics “tire out.”

What is an aerospace engineer?

Aerospace engineers are directly involved with putting objects—from airplanes and

the space shuttle to deep-space craft—into the sky and beyond. Using sundry mathe-

matical models and techniques, they install, construct, maintain, and test systems

used to launch, diagnose, or track aircraft and space vehicles. They may calibrate test

equipment and determine causes of equipment malfunctions. Using computers and

communications systems, aerospace engineers often record and interpret test data.

What is orbital mechanics?

344 Orbital mechanics, also called flight mechanics, is the study of the motions of artificial

early

high

failures

electronics

wear out

Calculations involving the common failure rates of various mechanical devices often results in a graph with a

bathtub-shaped curve.