Quandaries and Queries


Hello Math Central,

My father asked me to submit a question about the so-called 'bathtub
curve'. If you cut a bathtub in half lengthwise down it's middle, the
edge of the tub would describe the 'bathtub curve' which can be used
to demonstrate typical failure rates of products. This curve is
characterised by high initial (infant mortality) failure rates at
it's beginning, which drop quickly to a very low level. Failures then
increase gradually to the "end of life" stage where the failure rate
takes off dramatically again.

If anyone in the math department knows about the so-called 'bathtub
curve' my father would really appreciate the equation. He is an
electrical engineer at SaskPower and I believe this equation would be
very useful in planning for the maintenance of equipment and
machinery. (Then we won't have any unexpected power failures!)

Thank you.




Hi David,

The best we can give you is some references we found in an Internet search.

System evolution and reliability of systems, and

The Bathtub Curve and Product Failure Behavior, part1 and part 2.

Chris and Ed