Reliability Prediction Considering Multiple Failure Mechanisms

The multiple temperature operational life (MTOL) testing method is used to calculate the failure in time (FIT) by a linear combination of constant‐rate failure mechanisms. This chapter demonstrates that, unlike other conventional qualification procedures, the MTOL testing procedure gives a broad description of the reliability from sub‐zero to high temperatures. This procedure can replace the more standard single‐condition high‐temperature operational life (HTOL) by predicting the system failure rate by testing a small number of components over more extreme accelerated conditions for much shorter times than is conventionally used. The result is a much more accurate result for the failure rate, calculating the mean time to failure (MTTF) based on much shorter time‐scale testing only a fraction of the number of components. Rather than testing 77 parts for 1000 h, a failure rate prediction can be obtained from as few as 15 parts tested for only 200 h with reliable results