How does repairman delay affect the reliability and availability of single-unit systems?
This study develops fuzzy semi-Markovian stochastic models to analyse how fuzziness and repairman arrival delay influence the mean time to system failure and availability of single-unit systems.
The authors formulated two stochastic models using a semi-Markovian approach and derived recursive relations for key reliability measures. The lifetime, failure time, repair time, and repairman arrival time were modelled using Lindley-distributed random variables, with uncertain parameters represented as fuzzy numbers through a bell-shaped membership function.
The study considers two system scenarios: one with immediate repair after failure and another where the system must wait for the repairman to arrive. Switching devices and repairs are assumed to restore the system to an as-good-as-new condition.
Numerical analysis using a Lindley-distributed random sample of size 1000 showed that increasing the α-cut reduces fuzziness and improves the accuracy of reliability estimates. The results also revealed that systems with immediate repairman availability achieve higher availability than systems affected by repairman arrival delay.
The findings recommend immediate repair facilities for single-unit systems where downtime is costly, while also showing how fuzzy reliability measures can guide maintenance planning and system-performance decisions.
This research contributes to reliability engineering, fuzzy stochastic modelling, semi-Markov processes, maintenance scheduling, Lindley lifetime analysis, and performance evaluation of repairable engineering systems.
📖 Read the full article here:
https://doi.org/10.46481/jnsps.2026.3438
Published in: Journal of the Nigerian Society of Physical Sciences