Abstract
The paper deals with reliability analysis of a three non-identical
complex unit system A, B and C arranged in such a way that the system
failure occurs only if either unit-A fails or both the units B and C
fail totally i.e. the units B and C are arranged in parallel network and
this parallel sub-system of units B and C is arranged with unit-A in
series network. There are two types of repairman: ordinary and expert
repairman. The expert repairman is called only when system breaks down.
Two types of repair facility is available to repair failed unit in which
A gets priority for repair and is repaired by expert and B and C are
repaired by ordinary repairman on first come first service basis.
Further, if unit A is repaired by expert and during the process unit B
or C fails, then that unit is also repaired by expert repairman till the
system becomes operative. The failure of units B and C are mutually
dependent i.e. the unit-B fails with increased failure rate if the
unit-C has failed. Similarly, the unit-C fails with increased failure
rate if the unit-B has failed. The failure time distributions of unit-A
is taken exponential. The distribution of time to failure of unit-B and
unit-C are also exponential. The distribution of time to repair of
unit-A, B and C is assumed to be general.