Downloaded from https://www.everyspec.com AM P 70610 A large digital computer Is designed as the heart of a bottlefield intelligence and fire direction system. Since only three systems are availat-le for test, and test time is limited to 2000 hr each, it is decided to use a sequential test. Investigate a me- quenttal test which demonstrates a mininum acceptable mean life of 1000 hr for a consumer and producer risk of 0. 1. 1. Mate the given test parameters and 1. a 0 * 10% choose a set of suitable equations. Xi - 1/1000-hr Use i•Iq. 3-32, 3-33, 3-34 with XtT. 2. Calculate a from Eq. 3-32. 2. a - Ink= *V .107. S, Construct A table which shows #I, A, S.
'v aj _ and X as a function of y, Use Table 3-9 and Eqs. 3-32, 3-33, 3-34, and 1.5 0.22 5.419 6.59 3-30. 2.0 0.721 3.170 4.40 3.0 0.607 2.000 3.30 .0 0.497 1.3888 .7 Now look at the table just constructed. If the sPplier is willing o taite a 10% chance of not passing the test (a large ohamos to tqke on a big contract), he must, for example, make the item 3 times as good as tor jirall y - 3) and test it for '3. 30/h, - 3300 hr ow 20 weeks" of total test time at a minir..Am (presumes no failuresi. For every failure, he must test for another "1/(t,?t) - 1650 hr w 10 weeks" If he is to pass the test.
If he ahooses to strive only for twice u good sN neoessary (vY - 2), then he must test for i minimum of "4.40/Ai 4400 hrv 3 6 weus" of total tost time; for every failure ho must test for another "1•67 hr w a weeks. " Moat suppliers don't want to take a 1.0% chance of fatling such an Impotant test, especially if their equip- ment is 2 to 3 times as good as required. The additirmul requirement that total test time be no more than "3 x 2000 hr - 6000 hr' hampers things even morel 6000 hr corresponds to a XIT of 6, which means that the -y 1.5 option is viot even open to him. .....-.....------