Reliability theory predicts that even those systems which are composed entirely of non-aging elements ( with a constant failure rate ) will nevertheless deteriorate ( fail more often ) with age, if these systems are redundant in irreplaceable elements.
12.
The bathtub curve is generated by mapping the rate of early " infant mortality " failures when first introduced, the rate of random failures with constant failure rate during its " useful life ", and finally the rate of " wear out " failures as the product exceeds its design lifetime.
