Vorlesung 5 und 6

….and l´Hopital… MTTF= integral(R(t)) !!

INDEPENCE

Reduction to components:

Rlow >= Rhigh, Rlow more effictive

or with R(x) = e^-lamda*x

Here: 2^5 possible configurations

• add start- and endpoint-number (first and last number)

• list: connection of every component to others, exept for destination!!

cuts: cut for which all components must fail to cause systeme failure

path: ..system functioning

minmal path (series) in parallel - complete opposite as tighter lower bound

Crude estimate:

lower bound: all components in series

upper bound: alle components in parallel

often not useful, because bounds are too wide

add additional component with reliability R´ in series

common powersource, common environmental conditions

minimal cuts (paralel) in series

• Contains different types of components

• m_x represents number of components of type x

lx = number of working components (of m_x); FORMULA NECCESARRY?

Cold standby: Standby component is not subject to failure until switched on

Hot standby: standyby component may fail while it is in standy mode

… is quantifying the ability of a system to fulfil its objective when considering maintenance

Corrective: replacement or repair of failed unit (item is allowd to fail)

Preventive: regular inspections (and eventual repair)

Conditioned: repair in case degradation is detected

And repair!

… Functions until failure, no repair action taken / allowed

——

-repair immediately after failure

-duration of repair: g(t) and G(t)

-time to failure: R(t)=e^-lamda*t

-probability of component being up at t: p(t)

components operating in standbymode must be periodically tested

components are unattended between tests

failure is revealed only when tested

availability p(t) and reliability R(t) are equivalent

tau: operation period, tau_r=preventive maintenance, tau_e: corrective maintenance, t: time to failure