Fundamental of Realibility Maintainbility & Availability

8/3/2019 Fundamental of Realibility Maintainbility & Availability

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FUNDAMENTAL OF RMA 1

FUNDAMENTAL OF RELIABILITY,MAINTAINABILITY & AVAILABILITY

RELIABILITY : CONCEPTS, APPLICATIONS AND BENEFITS

DEFINITION : RELIABILITY IS THE PROBABILITY THAT PARTS PRODUCTS

OR SYSTEMS WILL PERFORM THEIR INTENDED FUNCTION WITHOUT

FAILURE IN SPECIFIED ENVIRONMENTS FOR DESIRED PERIODS OR THECAPACITY OF A PRODUCT TO OPERATE AND NOT FAIL.

PAST NOW FUTURE

STATISTIC : THE SCIENCE OF PROBABILITY : THE SCIENCEANALYSIS OF HISTORICAL DATA PREDICTING THE

POSSIBILITYOF FUTUREEVENTS

" UNDERSTAND THE PAST " "PREDICT THE FUTURE":


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SUCCESS OF A BUSINESS DEPENDS ON CUSTOMER SATISFACTION

GOOD PRODUCTS / SERVICES

ACCEPTABLE PRICE

RELIABLE PRODUCTS /SERVICES

CASE HISTORIES :

HEWLETT-PACKARD

F-105 WEAPON SYSTEM

TEXAS INSTRUMENTS

ATLAS GUIDANCE SYSTEM

GENERAL MOTOR

MD HYDRAULIC PUMP

US NAVY SUPPLY

AT & T


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REASONS FOR RELIABILITY

INCREASING PRODUCTS COMPLEXITY

CUSTOMERS AND PUBLICS ARE BECOMING MORE RELIABILITY CONSCIOUS

WORLD COMPETITION

PRODUCTS ARE ADVERTISED BY THEIR RELIABILITY INDEX

DEMAND FOR HIGHER STANDARDS AND MORE COMFORTABLE MODES OFLIVING

SATISFACTION = f (R, M, S & Q)

BENEFITS, SEE CASE HISTORIES RELIABILITY CLAUSES IN CONTRACT AND SPECIFICATION


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FUNDAMENTAL OF REALIBILITY,MAINTAINBILITY & AVAILABILITY

Influence of number of component to product's reliability

APPLICATIONS

INDUSTRIES THAT MAKE INTENSIVE USE OF TECHNOLOGY( computers, aircraft, spacecraft, satellite, cars, robotics,telecommunication )

INDUSTRIES THAT RELY HEAVILY ON ASSEMBLY LINES( communication equipment, NC machine, large construction machine )

INFORMATION INDUSTRIES( computer programming, artificial intelligence )

MAINTENANCE / LOGISTIC ENGINEERING

Number of component Ri = 99.999 % Ri = 99.99 %

100 Rs = 99.90 % Rs = 99.01 %

250 Rs = 99.75 % Rs = 97.53 %

1000 Rs = 99.01 % Rs = 95.12 %


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BENEFITS BASIS FOR PRODUCT / DESIGN COMPARISON AND SUPPLIERS EVALUATION

REDUNDANCY EVALUATION

ESTABLISH FAILURE REPORTING SYSTEM

PREDICTS THE LIFE OF THE PRODUCTS

DETERMINE OPTIMUM BURN-IN PERIOD

DETERMINE OPTIMUM WARRANTY PERIOD AND COST

DETERMINE OPTIMUM PREVENTIVE MAINTENANCE /REPLACEMENT TIME

DETERMINE SPARE PARTS REQUIREMENTS

OPTIMIZE INVENTORY COST

HELP PROMOTES SALES ON THE BASIS OF RELIABILITY INDEX


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OPTIMIZATION OF RELIABILITY

THE QUESTION............????????

WHAT SHOULD BE THE LEVEL OF RELIABILITY THAT SHOULD BE

DESIGNED, MANUFACTURED AND MAINTAINED INTO A PRODUCT

THE ANSWER.................!!!!!!!!!

THE OPTIMUM RELIABILITY LEVEL AT WHICH THE LIFE CYCLE COST OF

THE PRODUCT IS MINIMUM


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MAINTAINABILITY : CONCEPT AND APPLICATIONS

DEFINITION : THE PROBABILITY OF SUCCESSFULLY PERFORMING AND

COMPLETING A SPECIFIED MAINTENANCE ACTION WITHIN A

RESCRIBED PERIOD OF TIME, WITH A SPECIFIED MANPOWER, SKILL,TEST EQUIPMENT, MANUAL AND FACILITIES, UNDER SPECIFIC

ENVIRONMENTAL CONDITION OR THE INHERENT ABILITY OF A

DESIGN TO BE MAINTAINED


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MAINTAINABILITY IS ONE OF SYSTEM DESIGN PARAMETER !!

MAINTENANCE AND MAINTAINABILITY

MAINTENANCE ACTION TAKEN BY A SYSTEM USER, TO RETAIN

AN EXISTING SYSTEM

MAINTAINABILITY ACTION TAKEN BY SYSTEM DESIGNER, DURING

DEVELOPMENT

FUNCTION ?

TO ENSURE THAT - WHEN PRODUCED, INSTALLED, AND OPERATED,

THE FIELDED SYSTEM / EQUIPMENT CAN BE MAINTAINED AT MINIMUMLIFECYCLE SUPPORT COST AND WITH MINIMUM DOWNTIME


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WHAT CAN WE EXPECT FROM MAINTAINABILITY IMPLEMENTATION ????

LOWER DOWN TIME , THEREFORE A HIGHER OPERATIONAL READINESS

(AVAILABILITY)

THE CAPABILITY OF BEING RESTORED QUICKLY TO OPERATING STATUS

(CORRECTIVE MAINTENANCE) THE CAPABILITY OF BEING RETAINED IN AN OPERATIONALLY READY

STATE (PREVENTIVE MAINTENANCE)


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DESIGN CRITERIA

MINIMIZE MAINT. TIMES, PERSONNEL, SKILL, EQUIPMENT AND

SPARES

PROVIDE DIAGNOSTIC AIDS FOR RAPID AND POSITIVE FAULT

IDENTIFICATION ACCESS TO EASE OF TROUBLESHOOTING, REMOVAL, REPLACEMEN

MODULER WITH MINIMUM INTER-CONNECT

STANDARDIZE PARTS AND TOOLS

GOOD IDENTIFICATION / LABELS OF PARTS AND TEST POINTS

CONNECTORS CAN NOT BE INADVERTENTLY INTERCHANGED

PROVIDE RESTS

SYSTEM SAFETY


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APPLICATION :

1. MAINTENANCE CENTER

2. AVIATION INDUSTRY

3. ENERGY, TELECOMMUNICATION SERVICE

BENEFITS:

1. BASIS FOR PRODUCT/DESIGN COMPARRISON AND VENDOR

EVALUATION

2. ESTIMATES MAINTENANCE TIME

3. BASIS FOR MAINTENANCE GUARANTEE4. ESTIMATES SYSTEM AVAILABILITY


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AVAILABILITY : CONCEPTS & APPLICATIONDEFINITION :

THE PROBABILITY THAT THE SYSTEM WILL OPERATESATISFACTORILY AT ANY POINT IN TIME WHEN USED UNDERSTATED CONDITION

TYPES OF AVAILABILITY

INHERENT AVAILABILITY

TAKING INTO ACCOUNT ONLY THOSE ITEMS WHICH AREINHERENT IN THE SYSTEM ( GENERALLY INCLUDES ONLY ACTIVE

REPAIR TIME ) ACHIEVED AVAILABILITY

A MEASURE OF AVAILABILITY OF A SYSTEM, INCLUDINGPREVENTIVE MAINTENANCE IN IDEAL SUPPORT (NO DELAY TIME)


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OPERATIONAL AVAILABILITY

EXTENTION OF THE ACTUAL OPERATING ENVIRONMENT

THE CONCEPT OF AVAILABILITY IS APPLICABLE TO :

REPAIRABLE SYSTEM

REQUIRED TO OPERATE CONTINUOUSLY

EXAMPLE :

TELECOMMUNICATION SYSTEM

ELECTRIC POWER GENERATION SYSTEM

DEFENSE SYSTEM

PETRO-CHEMICAL INDUSTRIES


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BENEFITS

1. BASIS FOR PRODUCT/DESIGN COMPARRISON AND VENDOR EVALUATION

2. ESTIMATES SYSTEM UP-TIME (OPERATION) WITHIN A CERTAIN PERIOD

3. BASIS FOR DESIGNING SYSTEM REDUNDANCY


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BASIC ANALYTICAL FUNCTIONS

RELIABILITY

PROBABILITY DENSITY FUNCTION

RELIABILITY FUNCTION

MEAN LIFE FUNCTION

TeTf

=)(

=1

)()( 1T

dTTfTR

=0

)( dTTTfm


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FAILURE RATE FUNCTION

CONDITIONAL RELIABILITY FUNCTION)(

)()(

TR

TfT =

)(

)(),(

TR

tTRtTR

+=


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MAINTAINABILITY

MAINTAINABILITY FUNCTION

MTTR

REPAIR RATE

MTTR

t

etM =1)(

= =

=N

i

N

i

iiitMTTR1 1

/

MTTR

1=


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AVAILABILITY

INHERENT AVAILABILITY

ACHIEVED AVAILABILITY

OPERATIONAL AVAILABILITY

MTTRMTBF

MTBFA

+

=

MMTBM

MTBMAa +

=

fMTBM

+=

1

MDTRTMTBM

RTMTBMA

+++

=0


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AVAILABILITY IMPROVEMENT

AVAILABILITY IS A COMBINED MEASURE OF RELIABILITY AND

MAINTAINABILITY

IT SHOULD BE MAXIMIZED IN THE MOST COST EFFECTIVE

MANNER !!

MAXIMIZE MTBF

MINIMIZE MTTR

PERFORM MAINTENANCE ON THE RUNNING SYSTEM

PRESCRIBED PREVENTIVE MAINTENANCE ACTION SHOULD BEMINIMIZED

USE AUTOMATIC TEST EQUIPMENT


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SERIES, PARALLEL AND STAND-BY SYSTEM

SERIES SYSTEM

RELIABILITY-WISE IN SERIES IF ONE OR MORE SUB-SYSTEM/COMPONENTFAILED, THEN THE WHOLE SYSTEM FAILED !!!!

RELIABILITY OF THE SYSTEM

R1

R3

R2

321RRRRs =


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WHAT ABOUT AVAILABILITY ?

BY DEFINITION ,

AVAILABILITY OF SERIAL SYSTEM IS GIVEN BY,MTTRMTBF

MTBF

A +=

=

=n

i

iS AA1


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PARALLEL SYSTEM

RELIABILITY-WISE IN PARALLEL, THE SYSTEM SURVIVED IF ONEOR MORE SUB-SYSTEM/COMPONENT SURVIVED

R1

R2

R3


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FUNDAMENTAL OF RELIABILITY,MAINTAINABILITY& AVAILABILITY

PARALLEL TYPE OF REDUNDANCY THE WAY TO IMPROVE SYSTEM RELIABILITY MAY BE EXPANDED TO k-out-of-n : G system

THE RELIABILITY OF PARALLEL SYSTEM IS

THE AVAILABILITY OF PARALLEL SYSTEM

(A + U ) = 1

WHERE U = UNAVAILABILITY

)1(1)(1

=

=N

i

is RtR


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FOR nUNITS IN PARALLEL, (FULL-ON REDUNDANCY)

THE SYSTEM AVAILABILITY,

OR USE THE BINOMIAL DISTRIBUTION

MAY BE EXPANDED TO D-OUT-OF-N:G

( )knk

n

dk

S UAkkn

nA

= = )(!!

!

( ) nnnnn UnAUUnAAUA ++++=+ 11 ..............................

11 .............................. +++= nnnS nAUUnAAA


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STAND-BY SYSTEM

A SYSTEM IS CONSIDERED TO BE STAND-BY SYSTEM IF ONLY THEREQUIRED UNITS ARE FUNCTIONING WHILE THE BACK-UP UNITS AREINACTIVE

BENEFITS : IMPROVES SYSTEM RELIABILITY (BETTER THAN PARALLEL )

LOWER FAILURE RATE ON STAND-BY UNITS

R1

R2


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THE RELIABILITY OF STAND-BY SINGLE SURVIVOR SYSTEM IS GIVENBY THE FOLLOWING EQUATION

THE MTBF

FOR MULTIPLE SURVIVOR (D-OUT-OF-N), REQUIRED MINIMUM dOUTOF nTO PERFORM THE FUNCTION

=

=1

0 !

)()(

n

x

tx

x

ettR

nm=

( )

( )

d

dnMTTF

xeTdTR

dn

x

Tdx

1

!)(

0

+=

=

=


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SIGNIFICANT IMPROVEMENT IN RELIABILITY !!!!!

THE AVAILABILITY

Where

Zi = (n-i)/d, if (n-i)/d < 1Zi = 1, if (n-i)/d 1

1

0

)1(

!

!

+

=

=

n

i

Z

Zj

indn

i

nS jdi

nPA

+=

=

=

1

0

1)1(

!

!1/1

n

i

Z

Zj

in

n

n

i

jdi

nP


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WHEN d= 1 (SINGLE SURVIVOR), REQUIRED ONLY ONE UNIT TOPERFORM THE FUNCTION

indn

i

nS

i

nPA

=

=

0 !

!

+=

=

1

0 !

!1/1

n

i

in

ni

nP


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Fundamental of Realibility Maintainbility & Availability