110 Improving reliability and quality for product success
over three times to 500 h, the materials in the structure will experience
the same kind of intensive wear-out and degradation, and thus failure.
There would in fact be many failures, assuming that the sample size is
the same as required for the minimum test hours. Therefore, the sample
size can be reduced drastically because a few failed samples are sufcient
to appraise item reliability. This results in economizing test expenses. In
addition, the greater the shape parameter, the more drastically the sample
size decreases. To save test expenses further, the shape parameter or the
severity of test conditions should be increased by reliability engineers.
Parametric ALT of lifetime testi ...