Analytical Quick Calculation Pad (QCP)
BlockSim includes a Quick Calculation Pad (QCP) for computing
useful metrics. You can access the QCP by choosing Analysis
> Analysis > Analytical QCP or by clicking its icon
on the Analytical page of the diagram control panel.
To perform a calculation, select the appropriate option and
enter any required inputs in the Input
area, then click Calculate.
For more detailed information on how to use the QCP in general,
see Quick Calculation
Pad (QCP).
The following calculations are available for analytical diagrams:
Reliability
Calculates the probability that a
new system will operate without failure for a given period
of time. Enter the time at which you wish to calculate the
reliability in the Mission
End Time field. The mission is assumed to start at
time = 0.
For example, a reliability of 90%
for a mission end time of 3 years means that if 100 identical
systems are fielded, then 90 of them will still be operating
at the end of 3 years.
Note:
Reliability calculations are available even when the linked
RBD or fault tree contains static blocks. If the diagram contains
one or more static blocks (i.e., blocks that use a constant
model), the mission end time for the static blocks is assumed
to be equal to the time for which the fixed reliability value
has been defined.
Probability
of Failure
Calculates the probability that a
new system will be failed in a given period of time. Enter
the time at which you wish to calculate the probability of
failure in the Mission End
Time field. The mission is assumed to start at time
= 0.
Probability of failure is also known
as unreliability and it is the inverse of the reliability.
For example, a probability of failure of 10% for a mission
end time of 3 years is equivalent to a 90% reliability.
Conditional
Reliability
Calculates the probability that a
system will successfully operate at a specific time interval
given that it has operated successfully up to a specified
time. Enter the start time of the interval in the Mission
Start Time field and enter the duration of the interval
in the Mission Additional
Time field.
For example, a system may have a reliability
of 90% for 3 years. If the system has operated for 2 years
without failure, the conditional reliability for an additional
year (for a total of 3 years of operation) may be 95%.
Note:
This assumes that all components start with the same accumulated
age; that is, all components start life at 0 and age to the
Mission Start Time
value. It is possible to consider an individual component
that has already accumulated some age (i.e., a used component)
in the same formulation by changing the block's Current
Age value in the Block Properties window.
Conditional
Probability of Failure
Calculates the probability that a
system will be failed at a specific time interval given that
it has not failed up to a specified time. Enter the start
time of the interval in the Mission
Start Time field and enter the duration of the interval
in the Mission Additional
Time field.
For example, a product may have a
10% probability of failure for 3 years. If the product has
operated for 2 years without failure, the conditional probability
of failure for an additional year (for a total of 3 years
of operation) may be 5%.
Reliable
Life
Calculates the estimated time at which
a specified reliability value will be achieved. Enter the
reliability goal in the Required
Reliability field. For example, a goal of 90% reliability
with a reliable life of 4 years means that if 100 identical
systems are fielded, then 90 of them will be still be operating
at the end of 4 years.
BX%
Life
Calculates the estimated time at which
a specified probability of failure will be achieved. Enter
the probability of failure in the BX%
Information At field. For example, a B10 life of 4
years means that the system has a 10% probability of failure
in 4 years of operation (note that this is equivalent to a
90% reliability with a reliable life of 4 years).
Note:
In the early days of reliability engineering, bearing manufacturers
used the term "B10 life" to refer to the time by
which 10% of the components would fail. Keeping with tradition,
ReliaSoft retained this nomenclature but replaced "10"
with "X," since the software allows you to get this
information at any percentage point and not just at 10% (e.g.,
B1, B5, etc.).
Mean
Life
Calculates the mean time to failure
for the non-repairable system in the diagram.
Note:
The mean life is a performance index and does not provide
any information about the behavior of the failure distribution
of the system.
Failure
Rate
Calculates the instantaneous number
of failures per unit time that can be expected at a certain
time given that the system survives to that age. Enter the
time at which you wish to calculate the failure rate in the
Time field.
For example, a failure rate of 0.01
at 100 hours means that a system that survives to 100 hours
has approximately a 1% probability of failure in the next
hour.