Question

Calculate mean time to failure, standard deviation, and design life for a continuously run, mechanical system: The failure rates are given per day as:

0.0007 0.001 0.0005 0.00001 0.0025 The hydraulic system is continuously operating. Calculate: a. MTTF b. Standard deviation C. The hydraulic system design life given that the desired reliability is 0.85

Answer 1

MTTF = 212.3142 days

standard deviation = 212.3142 days

the hydraulic system design life = 34.5051 days given that the desired reliability is 0.85

for exponential distribution function

standard deviation = mean

Note:

Sydhen failure rate (as) = x + Q2 + az tay the exponenhal distribution function For mean Standard deviation mean o (sd) = / Yas de E u

ai 0.0001 = 0.001 ng -0.0005 dy 0.0000) 0.0095 dz Since the dystem components follows CFR Sychem failure nake n E di 1-1 d. + det agt det do = 0.0007 +0.001 +0.0001 + 0.00001 + 0.0095 = 0.00471 From Practical Reliability Enginering (Fifth edition) Patrick D... O'CONNOR Willy P.No: 35 Mean time to failure, MITTE x Yas You out = 212.314 2 days From P.NO: 48 sa Yos MTBF (= SD), o ord Standard deviation 212. 3142 days The hydraulic enyaterri design life (t) given that do y desired reliability R(t) = exp(-18) (R(t)) is 0.85 exp (-0.00471 xt) (Fake " in on both sides) In 20.86) - (-0.00471 xt) t: 34.505) days 0.85 -

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