RELIABILITY MODELING OF A MAINTAINED SYSTEM WITH WARRANTY AND DEGRADATION
This paper discusses a maintained system with the concept of warranty and degradation. Repair and preventive maintenance (PM) costs are carried by the manufacturer during warranty while the cost of repair will be charged to the user beyond warranty. There is single repairman who is always available with the system for PM, repair and replacement of the unit. During warranty, unit goes under PM and works as new after PM. The unit beyond warranty works with some reduced capacity after its repair and so is called a degraded unit. Degraded unit is replaced by new unit after its failure. The time to failure of the system follows negative exponential distribution while repair, replacement and PM time distributions are taken as arbitrary. The expressions for reliability, mean time to system failure (MTSF), availability and profit function have been determined by using supplementary variable technique. Using Abel’s lemma, steady state behaviour of the system has been examined. Numerical results for reliability and profit function are also evaluated for particular values of various parameters and repair cost.