Age Based Overhaul Policy for Multiple Repairable Systems with Imperfect Maintenance: Case Study of Aero Engines

Garima Sharma,Rajiv Nandan Rai

doi:10.33889/ijmems.2021.6.1.012

Abstract

Reliability analysis of complex multiple repairable systems (MRS) such as aero engines, rolling stocks and nuclear power plants has always been an area of interest for the research fraternity. An appropriate age based overhaul maintenance policy for such systems can provide impetus to the operations. The paper proposes two different age based maintenance policies; Policy-I and Policy-II, to evaluate the overhaul time of an aero engine, where Policy-I considers MRS with imperfect corrective maintenance (CM), whereas Policy-II examines MRS with both imperfect CM and preventive maintenance (PM). The paper then provides a spare parts estimation model for both the policies. The developed policies and spares parts model are validated by considering field failure data of aero engines as a case and the obtained results are compared with the existing time based maintenance policy used for aero engines. The paper recommends the best policy to be used for MRS in general and the considered case in particular.

Highlights

Complex and large systems such as aero engines or locomotives cannot be treated as non-repairable systems since repair actions (Sheu et al, 2014) are required to be performed when they fail and are categorized as repairable systems (RS) (Rigdon and Basu, 2000)
The work done in this paper is largely inspired by the industries which deal with repairable systems and face problems in estimating an optimized overhaul time for deteriorating mechanical systems
Considering this issue, this paper proposes two age based overhaul policies (Policy I and Policy II)

Summary

Introduction

Complex and large systems such as aero engines or locomotives cannot be treated as non-repairable systems since repair actions (Sheu et al, 2014) are required to be performed when they fail and are categorized as repairable systems (RS) (Rigdon and Basu, 2000). Reliability analysis ( Yamamoto et al, 2012) of repairable systems is carried out by treating the system either as a single repairable system (SRS) or multiple repairable systems (MRS) (Garmabaki et al, 2016). MRS analysis portray a larger picture of the system’s condition compared to SRS. One of the most reliable model available in the literature for the analysis of RS is the generalized renewal process (GRP) proposed by Kijima (Kijima and Sumita, 1986; Kijima, 1989). The generalized renewal process is based on the virtual age concept and very much appreciated by present research fraternity and applied extensively for imperfect repair (Brown and Proschan, 1983; Pham and Wang, 1996) reliability analysis. Kijima proposes two virtual age based models: Kijima model I (KI) states that the ith repair can only remove the effect of damages incurred since (i − 1)threpair (equation 1) whereas according to Kijima model II (KII) the ith repair can collectively restore the damages up to the present time (equation 2)

Methods

Results

Conclusion