BTP Stage 2 Mid

8/13/2019 BTP Stage 2 Mid

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Indian Institute of Technology Indore

2012-13

B-Tech ProjectStage II

on

Prognosis and maintenance planningof mechanical components

Submitted by: Guided by:Janam Shah Dr. Bhupesh K. Lad0900305Astha Jain

0900313


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Introduction to Group Maintenance

Any machine has 3 types of interactions between itscomponents which can be classified as:

Economic dependence

Structural dependence Stochastic dependence

Most of the multi-component maintenance modelsconsider one of these dependences. Economic

dependency is a major one therefore we considered it inour model.


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RCM(Reliability Centered Maintenance)

RCM is defined as an approach to maintenance thatcombines corrective, preventive, predictive, and design outmaintenance practices and strategies so that the equipment

functions in the required manner. RCM incurs minimum maintenance cost It recognizes four maintenance techniques and on which

equipment, which technique to apply is decided by it.


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Categories of RCM

1) Run-to-Failure:

It is a decision taken by the analysis of what facility functionswould be affected by system failure versus the (life cycle)cost of preventing failure.

2) Preventive maintenance:It is the most basic scheduled maintenance. It schedules task

based on the time since that task was last performed.


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3) Condition Based Maintenance: It is based on predictive testing and inspection. Real-time

data are gathered and analyzed which tells us when theequipment requires maintenance.

4) Design Out Maintenance:

It is applying the lessons learned from past maintenanceexperience to future situations. This includes writing betterspecifications, precision rebuild, failed part analysis, androot-cause failure analysis.


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Group Maintenance Strategies

Remaining Useful Life (RUL) based group maintenance Remaining Useful Life (RUL) based group maintenance with

varying parameters

Age based group maintenance Group maintenance considering both RUL and age


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Introduction to @RISK

In our current models we have used RISK Optimizer tosolve the optimization model. It uses Genetic Algorithm(GA) to solve the problem. In this algorithm, at eachiteration an initial population of parameter setsrepresenting potential solutions to the search isgenerated. These parameter sets are encoded as stringsof binary digits. At the start of the GA run, thispopulation is generated by choosing points in the searchdomain at random.


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General Assumptions

Components are taken in series, even if one fails themachine will be down, hence downtime cost is takenconstant

Assembling-dissembling time of the machine is constant, ifit is opened once all components can be replaced/repairedas components are assumed to be structurallyindependent.

The components which are not included in preventivegroup maintenance are correctively maintained.


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Given: Mean () and standard deviations () of RUL for all the

components Cost of the components (C 1-C5) (Rs) Mean Time To Replace (MTTR 1) of the components (hrs) Mean Time To Assemble-Dissemble for machine (MTTR 2)

(hrs) Mean Time To Assemble-Dissemble for individual

components for corrective maintenance (MTTR 3) (hrs) Labour Rate (C L) (Rs/hr) Downtime cost (C

DC)(Rs/hr)

RUL based Group Maintenance


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Model cost of preventive maintenance of components in groupCost of preventive group maintenance= Cost of component(s) +(Mean Time to replace the component(s) + Mean time to assemble-dissemble the machine)*(Labour rate + Downtime cost)

CPM = C#+ ( MTTR#1 + MTTR2)*(CL + CDC) (# Components whose preventive maintenance is done are to beincluded)

Model for cost of corrective maintenance Cost of corrective maintenance of a component = Cost ofcomponent + (Mean time to replace the component + Mean timeto assemble-dissemble the component)*(Labour rate + Downtimecost)

C(CM)i = Ci + (MTTR1 + MTTR3)*(CL + CDC)

Total cost of group maintenance Total Cost of group maintenance (C T) = Cost of preventive groupmaintenance (C PM) + Cost of corrective maintenance of remainingcomponents (C CM)

CT= CPM + CCM


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Model definition:


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Results and Conclusion

On simulating, we get minimum cost by preventively

maintaining components 1, 3 and 5.

P r o

b a b i l i t y o

f o c c u r r e n c e

Total Cost


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RUL based group maintenance with varyingparameters

It is similar to the previous model only the Mean Time ToRepairs (MTTR 1 , MTTR2 and MTTR 3 ) are varying, i.e. they are

taken with log-normal distribution .


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Results and Conclusion

Minimum cost= 1,03,351Mean cost= 1,46,682Optimum solution occurs by doing preventive maintenance of 1, 3 and 5

M

i n . C

o s t

No. of trials


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Age based group maintenance

Given : Cost of components Current age of components Shape parameter Scale parameter Mean Time To Replace (MTTR 1) of the components (hrs) Mean Time To Assemble-Dissemble for machine (MTTR 2) (hrs) Mean Time To Assemble-Dissemble for individual components

for corrective maintenance (MTTR 3) (hrs) Labour Rate (C L) (Rs/hr) Downtime cost (C DC)(Rs/hr)


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Model cost of preventive maintenance of components in groupCost of preventive group maintenance= Cost of component(s) +(Mean Time to replace the component(s) + Mean time to assemble-dissemble the machine)*(Labour rate + Downtime cost)

CPM = C#+ ( MTTR#1 + MTTR2)*(CL + CDC) (# Components whose preventive maintenance is done are to beincluded)

Model for cost of corrective maintenance

Cost of Corrective group maintenance = (No. of failures)*{Cost ofcomponent + (Mean time to replace the component + Mean timeto assemble-dissemble the component)*(Labour rate + Downtimecost)}

C(CM)i = Nf *{Ci + (MTTR1 + MTTR3)*(CL + CDC)}Where Nf= (- V/)^ *( t+V)/+^

Total cost of group maintenance Total Cost of group maintenance (C T) = Cost of preventive groupmaintenance (C PM) + Cost of corrective maintenance of remainingcomponents (C CM)

CT= CPM + CCM


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Model definition:


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References

Rommert Dekker, Wildeman Ralphe , A Review of Multi -Component Maintenance Models with Economic Dependence, Mathematical Methods of Operations Research 45:411-435, 1997.

Moghaddam Kamran S & Usher John S., A new multi -objective

optimization model for preventive maintenance and replacementscheduling of multi- component systems , Department ofIndustrial Engineering, University of Louisville, 2010.

Zhigang Tian, Youmin Zhang, and Jialin Cheng, Condition BasedMaintenance Optimization for Multi- component Systems, Concordia University, Montreal, Quebec, H3G2W1, Canada

www.palisade.com


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