| 摘要: | 在可靠度分析中, 加速壽命試驗是指將受測物件置於較正常使用下嚴厲的環境應力中,
以縮短試驗時間的一種方法。本文考慮受測物件是由兩個零件串聯而成, 且零件平均壽
命服從獨立的指數分配, 分別在V-準則、D-準則與A-準則下, 探討兩應力水準恆定
應力加速壽命試驗(two-level constant-stress ALT , CSALT) 與兩應力水準階段應力加速壽命試驗(two-level step-stress ALT , SSALT) 之最佳化問題, 並比較兩最佳化試驗之優劣。在型一設限下, 可由數值結果看出最佳SSALT 在三個準則下皆優於最佳CSALT
在無設限下, 我們証明了兩最佳化試驗可得到相同的估計精確度。另外我們以最佳CSALT 作為基準試驗進行SSALT 之等效試驗計畫, 探討在三個準則下之成本效益, 並以實際例子說明, SSALT 只需較少的樣本數或可以縮短試驗的時間。
Accelerated life testing (ALT) is a process of testing products by subjecting it to strict
conditions, in order to observe more failure data in a short time period. In this thesis,
we consider the ALT of series system, each consists of two components whose life time
distributions follow independent exponential distributions. Optimal designs on the sample
allocation for the two-level constant-stress ALT(CSALT) and on the time for changing stress
levels for the two-level step-stress ALT(SSALT) are considered based on V-optimality, D-
optimality and A-optimality, respectively. Under Type-I censoring, it shows, by numerical
results, that the optimal SSALT is better than the optimal CSALT in terms of the resulting
objective functions. We also prove that the two optimal ALTs are indeed equivalent without
censoring. In addition, we use the optimal CSALT as the baseline ALT to obtain an equivalent
SSALT plan. A real data is analyzed to demonstrate the performance of both ALT plans
under the three optimality criteria as well as the equivalent test plans. |
