Optimal periodic replacement policy for a two-unit system with failure rate interaction

2005 ◽  
Vol 29 (3-4) ◽  
pp. 367-371 ◽  
Author(s):  
Min-Tsai Lai ◽  
Ying-Chang Chen
Keyword(s):  
Failure Rate ◽  
Replacement Policy ◽  
Unit System ◽  
Rate Interaction ◽  
Periodic Replacement ◽  
Failure Rate Interaction

REPLACEMENT MODEL WITH CUMULATIVE REPAIR COST LIMIT FOR A TWO-UNIT SYSTEM UNDER FAILURE RATE INTERACTION BETWEEN UNITS

2012 ◽  
Vol 19 (05) ◽  
pp. 1250023 ◽  
Author(s):  
MIN-TSAI LAI
Keyword(s):  
Failure Rate ◽  
Replacement Policy ◽  
Repair Cost ◽  
Unit System ◽  
Model Combining ◽  
Long Run ◽  
Replacement Model ◽  
Rate Interaction ◽  
Failure Rate Interaction ◽  
Cost Limit

In this paper, a periodical replacement model combining the concept of cumulative repair cost limit for a two-unit system with failure rate interaction is presented. In this model, whenever unit 1 fails, it causes a certain amount of damage to unit 2 by increasing the failure rate of unit 2 of a certain degree. Unit 2 failure whenever occurs causes unit 1 into failure at the same time and then the total failure of the system occurs. Without failure rate interaction between units, the failure rates of two units also increase with age. When unit 1 fails, the necessary repair cost is estimated and is added to the accumulated repair cost. If the accumulated repair cost is less than a pre-determined limit L, unit 1 is corrected by minimal repair. Otherwise, the system is preventively replaced by a new one. Under periodical replacement policy and cumulative repair cost limit, the long-run expected cost per unit time is derived by introducing relative costs as a criterion of optimality. The optimal period T* which minimizes that cost is discussed. A numerical example is given to illustrate the method.

OPTIMAL DISCRETE-TIME PERIODIC REPLACEMENT POLICY FOR REPAIRABLE PRODUCTS UNDER FREE MINIMAL REPAIR WARRANTY

2012 ◽  
Vol 29 (03) ◽  
pp. 1240020
Author(s):  
FU-MIN CHANG ◽  
YU-HUNG CHIEN
Keyword(s):  
Failure Rate ◽  
Discrete Time ◽  
Replacement Policy ◽  
Cost Models ◽  
Minimal Repair ◽  
Warranty Period ◽  
Long Run ◽  
Periodic Replacement ◽  
The Cost ◽  
Time Periodic

This paper presents the effects of a free minimal repair warranty (FMRW) on the periodic replacement policy under discrete operating circumstance. For the discrete-time periodic replacement policy, a product is preventively replaced at pre-specified operation cycles N, 2N, 3N, … (N = 1, 2, …). When the product fails, a minimal repair is performed at the time of failure and the failure rate is not disturbed by each repair. From the customer's perspective, the cost models are developed for both a warranted and a nonwarranted product, and the corresponding optimal periodic replacement policies are derived such that the long-run expected cost rates are minimized. Under the assumption of the discrete time increasing failure rate (IFR), the existence and uniqueness of the optimal N* are shown, and the impacts of a FMRW on the optimal replacement policies are investigated analytically. We found that the optimal N* for a warranted product should be adjusted toward the end of the warranty period.

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