scholarly journals Preventive replacement with defaulting

2020 ◽  
Vol 31 (4) ◽  
pp. 491-504 ◽  
Author(s):  
N M Alotaibi ◽  
C A V Cavalcante ◽  
R S Lopes ◽  
P A Scarf
Keyword(s):  
Numerical Study ◽  
Economic Cost ◽  
Time To Failure ◽  
Bernoulli Trials ◽  
Component Reliability ◽  
Cost Rate ◽  
Preventive Replacement ◽  
Standard Scenario ◽  
Critical Age ◽  
Age Replacement

Abstract This paper models age replacement and block replacement when there is the possibility of defaulting on the planned maintenance. A default occurs when a planned preventive replacement is not executed, and we discuss how defaults can arise in practice. Our aim is to study the robustness of block replacement and age replacement, bearing in mind that (a) these policies are frequently used in practice, (b) in the standard scenario (no defaulting) age replacement has a lower economic cost rate than block-replacement and (c) block replacement is simple to manage because component age does not have to be monitored. We model defaults as independent Bernoulli trials. We prove that a cost-minimizing critical age for replacement in the age policy with defaulting exists if the time to failure distribution has an increasing failure rate. A numerical study of the policies indicates that: age replacement is effective if maintenance control is good, that is, when there is only a small chance of defaulting; block replacement is relatively robust to defaulting (postponement), but less so to lack of knowledge about component reliability.

On classes of life distributions based on the mean time to failure function

2021 ◽  
Vol 58 (2) ◽  
pp. 289-313
Author(s):  
Ruhul Ali Khan ◽  
Dhrubasish Bhattacharyya ◽  
Murari Mitra
Keyword(s):  
Damage Model ◽  
Replacement Policy ◽  
Time To Failure ◽  
Mean Time To Failure ◽  
Moment Convergence ◽  
Life Distributions ◽  
Cumulative Damage Model ◽  
The Mean ◽  
Age Replacement ◽  
Mean Time

AbstractThe performance and effectiveness of an age replacement policy can be assessed by its mean time to failure (MTTF) function. We develop shock model theory in different scenarios for classes of life distributions based on the MTTF function where the probabilities $\bar{P}_k$ of surviving the first k shocks are assumed to have discrete DMTTF, IMTTF and IDMTTF properties. The cumulative damage model of A-Hameed and Proschan [1] is studied in this context and analogous results are established. Weak convergence and moment convergence issues within the IDMTTF class of life distributions are explored. The preservation of the IDMTTF property under some basic reliability operations is also investigated. Finally we show that the intersection of IDMRL and IDMTTF classes contains the BFR family and establish results outlining the positions of various non-monotonic ageing classes in the hierarchy.

A weak derivative approach to optimization of threshold parameters in a multicomponent maintenance system

2001 ◽  
Vol 38 (02) ◽  
pp. 386-406 ◽  
Author(s):  
Bernd Heidergott
Keyword(s):  
Optimization Problems ◽  
Estimation Algorithm ◽  
Replacement Policy ◽  
Cost Performance ◽  
Weak Derivative ◽  
Preventive Replacement ◽  
Maintenance System ◽  
Threshold Optimization ◽  
Age Replacement ◽  
The Cost

We consider a multicomponent maintenance system controlled by an age replacement policy: when one of the components fails, it is immediately replaced; all components older than a threshold age θ are preventively replaced. Costs are associated with each maintenance action, such as replacement after failure or preventive replacement. We derive a weak derivative estimator for the derivative of the cost performance with respect to θ. The technique is quite general and can be applied to many other threshold optimization problems in maintenance. The estimator is easy to implement and considerably increases the efficiency of a Robbins-Monro type of stochastic approximation algorithm. The paper is self-contained in the sense that it includes a proof of the correctness of the weak derivative estimation algorithm.

scholarly journals Filling machine preventive maintenance using age replacement method in PT Lucas Djaja

2018 ◽  
Vol 154 ◽  
pp. 01056
Author(s):  
Fifi Herni Mustofa ◽  
Ria Ferdian Utomo ◽  
Kusmaningrum Soemadi
Keyword(s):  
Maintenance Cost ◽  
Time To Failure ◽  
High Failure Rate ◽  
Corrective Maintenance ◽  
Replacement Method ◽  
Critical Components ◽  
Age Replacement ◽  
Engine Maintenance ◽  
A Company ◽  
Mean Time

PT Lucas Djaja is a company engaged in the pharmaceutical industry which produce sterile drugs and non-sterile. Filling machine has a high failure rate and expensive corrective maintenance cost. PT Lucas Djaja has a policy to perform engine maintenance by way of corrective maintenance. The study focused on the critical components, namely bearing R2, bearing 625 and bearing 626. When the replacement of the failure done by the company is currently using the formula mean time to failure with the result of bearing R2 at point 165 days, bearing 625 at a point 205 days, and bearing 626 at a point 182 days. Solutions generated by using age replacement method with minimization of total maintenance cost given on the bearing R2 at a point 60 days, bearing 625 at the point of 80 days and bearing 626 at a point 40 days.

scholarly journals Heat Transfer Behavior of Green Roof Systems Under Fire Condition: A Numerical Study

Buildings ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 206
Author(s):  
Gerzhova ◽  
Blanchet ◽  
Dagenais ◽  
Côté ◽  
Ménard
Keyword(s):  
Heat Transfer ◽  
Failure Time ◽  
Numerical Study ◽  
Fire Hazard ◽  
Green Roof ◽  
Green Roofs ◽  
Heat Transfer Process ◽  
Heat Fluxes ◽  
Substrate Thickness ◽  
Time To Failure

Currently, green roof fire risks are not clearly defined. This is because the problem is still not well understood, which raises concerns. The possibility of plants catching fire, especially during drought periods, is one of the reasons for necessary protection measures. The potential fire hazard for roof decks covered with vegetation has not yet been fully explored. The present study analyzes the performance of green roofs in extreme heat conditions by simulating a heat transfer process through the assembly. The main objective of this study was to determine the conditions and time required for the roof deck to reach a critical temperature. The effects of growing medium layer thickness (between 3 and 10 cm), porosity (0.5 to 0.7), and heating intensity (50, 100, 150, and 200 kW/m²) were examined. It was found that a green roof can protect a wooden roof deck from igniting with only 3 cm of soil coverage when exposed to severe heat fluxes for at least 25 minutes. The dependency of failure time on substrate thickness decreases with increasing heating load. It was also found that substrate porosity has a low impact on time to failure, and only at high heating loads.

A hybrid preventive maintenance model for systems with partially observable degradation

2020 ◽  
Vol 31 (3) ◽  
pp. 345-365 ◽  
Author(s):  
Maxim Finkelstein ◽  
Ji Hwan Cha ◽  
Gregory Levitin
Keyword(s):  
Preventive Maintenance ◽  
Replacement Policy ◽  
Hybrid Strategy ◽  
Cost Rate ◽  
Shot Noise Process ◽  
Shock Process ◽  
Long Run ◽  
Age Replacement ◽  
Partially Observable ◽  
Maintenance Model

Abstract A new model of hybrid preventive maintenance of systems with partially observable degradation is developed. This model combines condition-based maintenance with age replacement maintenance in the proposed, specific way. A system, subject to a shock process, is replaced on failure or at some time ${T}_S$ if the number of shocks experienced by this time is greater than or equal to m or at time $T>{T}_S$ otherwise, whichever occurs first. Each shock increases the failure rate of the system at the random time of its occurrence, thus forming a corresponding shot-noise process. The real deterioration of the system is partially observed via observation of the shock process at time ${T}_S$. The corresponding optimization problem is solved and a detailed numerical example demonstrates that the long-run cost rate for the proposed optimal hybrid strategy is smaller than that for the standard optimal age replacement policy.

Probabilistic Analysis of a Preemptive Replacement of an NPP Component With a Component of Superior Material

2005 ◽  
Author(s):  
Robert K. Perdue ◽  
Joel Woodcock ◽  
Laurent Houssay
Keyword(s):  
Nuclear Power ◽  
Tube Bundle ◽  
Economic Value ◽  
Economic Consequences ◽  
Management Tool ◽  
Time To Failure ◽  
Plant Component ◽  
Superior Corrosion Resistance ◽  
Age Replacement ◽  
The Cost

The Westinghouse proactive aging management tool, PAM, considers three major sets of variables when calculating the NPV or economic value of age replacement: (a) the projected time to failure, (b) the economic consequences of unplanned failure and (c) the cost of the replacement. All of these variables will typically be uncertain; particularly the time to part failure. A not uncommon complication in evaluating whether and when to replace a degrading component or part in a plant is that the replacement part is thought to have a longer expected life (be more resistant to degradation) but, to date, there is little field experience to substantiate that belief. This paper shows how two different approaches for statistical estimation of a Weibull failure distribution can be used in tandem to surmount this problem, and illustrates it within the context of the replacement of a nuclear power plant component tube bundle with a tube bundle expected to provide superior corrosion resistance.

RELIABILITY PROPERTIES OF MEAN TIME TO FAILURE IN AGE REPLACEMENT MODELS

2010 ◽  
Vol 17 (01) ◽  
pp. 15-26 ◽  
Author(s):  
G. ASHA ◽  
N. UNNIKRISHNAN NAIR
Keyword(s):  
Residual Life ◽  
Stochastic Orders ◽  
Mean Residual Life ◽  
Time To Failure ◽  
Mean Time To Failure ◽  
Replacement Model ◽  
The Mean ◽  
Age Replacement ◽  
The Relationship ◽  
Mean Time

In this article some properties of the mean time to failure in an age replacement model is presented by examining the relationship it has with hazard (reversed hazard) rate and mean (reversed mean) residual life functions. An ordering based on mean time to failure is used to examine its implications with other stochastic orders.

AN OPPORTUNITY-BASED AGE REPLACEMENT POLICY CONSIDERING WARRANTY

1999 ◽  
Vol 06 (03) ◽  
pp. 229-236 ◽  
Author(s):  
BERMAWI P. ISKANDAR ◽  
HIROAKI SANDOH
Keyword(s):  
Time Distribution ◽  
Failure Time ◽  
Sufficient Conditions ◽  
Replacement Policy ◽  
Minimal Repair ◽  
Failure Time Distribution ◽  
Warranty Period ◽  
Preventive Replacement ◽  
Long Run ◽  
Age Replacement

This study discusses an opportunity-based age replacement policy for a system which has a warranty period (0, S]. When the system fails at its age x≤S, a minimal repair is performed. If an opportunity occurs to the system at its age x for S<x<T, we take the opportunity with probability p to preventively replace the system, while we conduct a corrective replacement when it fails on (S, T). Finally if its age reaches T, we execute a preventive replacement. Under this replacement policy, the design variable is T. For the case where opportunities occur according to a Poisson process, a long-run average cost of this policy is formulated under a general failure time distribution. It is, then, shown that one of the sufficient conditions where a unique finite optimal T* exists is that the failure time distribution is IFR (Increasing Failure Rate). Numerical examples are also presented for the Weibull failure time distribution.

scholarly journals Penentuan Interval Waktu Penggantian Komponen Kritis Pada Mesin Volpack Menggunakan Metode Age Replacement

2017 ◽  
Vol 16 (2) ◽  
pp. 92
Author(s):  
Yanuar Yuda Prawiro
Keyword(s):  
Cost Savings ◽  
Solenoid Valve ◽  
Time Interval ◽  
Preventive Replacement ◽  
Replacement Method ◽  
Schedule Interval ◽  
Age Replacement ◽  
Engine Components ◽  
A Company ◽  
Replacement Time

CV. Cool Clean is a company engaged in packing tissue. During this time the company only perform corrective action that causes disruption of the production process due to frequent damage of a sudden the engine components volpack. In this study used a model of preventive replacement that can reduce downtime and costs. The method used to obtain the schedule interval a critical component is age replacement method. Seal heater obtained replacement time interval of 30 days with a 22% reduction in downtime. Replacement interval for knife foil is 26 days with a 27% reduction in downtime. Replacement interval for solenoid valve is30 days with a 29% reduction in downtime. Replacement interval forOring seal is 18 days with a 29% reduction in downtime. Replacement interval for needle bearing is 62 days with a 25% reduction in downtime. Results of this study also showed that by applying age replacement can save costs for seal heater Rp. 974.000 or 23%. Knife foil cost savings of Rp. 1.251.409 or 22%. Solenoid valve cost savings of Rp.546.539 or 24%. Oring seal cost savings of Rp. 350.096 or 26%. And needle bearing cost savings of Rp. 196.712 or 26%.

scholarly journals Reliability modelling and maintenance policy optimization for a repairable parallel system

2021 ◽  
Author(s):  
Reza Ahmadi ◽  
Shaomin Wu ◽  
Amirhossein Sobhani
Keyword(s):  
Integrated Approach ◽  
Maintenance Policy ◽  
Cost Rate ◽  
Preventive Replacement ◽  
State Process ◽  
Reliability Modelling ◽  
Proposed Model ◽  
Average Cost Rate ◽  
Policy Optimization ◽  
Hidden Failures

This paper proposes an integrated approach for reliability modelling and maintenance scheduling of repairable parallel systems subject to hidden failures. The system consists of heterogeneous redundant subsystems whose failures are revealed only by inspections. Inspections at periodic times reveal the components state and repair actions are decided by the excursion of a basic state process describing the total number of failed components in each subsystem. Using the standard renewal arguments, the paper aims at minimizing the average cost rate by the joint determination of the optimal inspection interval, the partial repair threshold and the preventive replacement threshold. We illustrate the procedure for the case as the components' lifetimes conform to the Weibull distribution. Numerical examples are used to illustrate the proposed model and the response of the optimal solutions to the model's parameters.

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