Presentation 1 Final Reliability

8/2/2019 Presentation 1 Final Reliability

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AKRAM H MOH MOAMER GS28368

RELIABILITY SYSTEMS

EMM5614 MAINTENANCE MANUFACTURINGMANAGEMENT

PROF.MADYA DR.TANG SAI HONGBY

AKRAM H. MOH. MOAMER GS28368

ANAS AHMED EL-HAG GS29898


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Reliability Definition

Reliability is a time dependent characteristic.

Reliability of a system is theprobability that the

given system will perform its required function

under specified conditions for a specified periodof time.


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Reliability for different configurations

1. Series Configuration

Overall reliability = Ro = R1 * R2 * R3. Rn

R1 R2 R3 Rn


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Series Configuration

If one subsystems component fails, theoverall system will fail.

Reliability in series system decreases when it

has more subsystems.


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Example of series system reliability

If a System with two Subsystems ( eachSubsystem works 85% of tested reliability) the

reliability of it will be :R Sys= R Subsys1 x RSubsys2 =0.85 x 0.85 = 0.772

but if the system with three Subsystems ofthe same reliability the reliability will be:

R Sys = R Subsys1 x R Subsys2 x R Subsys3 = 0.85 x0.85 x 0.85 = 0.615


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Reliability in series chart

Average Reliability of all Components (Percent)

Reliabili

tyoftheSystem(

Percent)

100

80

60

40

20

0100 99 98 97 96

n=1


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Example - Communications System


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Suppose we are concerned about the

reliability of the controller, server and

transformer. Assume that these components

are independent, and that

R controller =0.95

R server =0.96

R transformer =0.99


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Since these three components connect in

series, the system A consisting of these

components has reliability:-

R system A

= P controller P server P transformer

=0.95*0.96*0.99=0.90


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Reliability for different configurations

2. parallel Configuration

Rs = 1 (1 R1)(1-R2)..(1-Rn)

R1

R2

Rn


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parallel Configuration

Reliability in parallel system increases when it

have more subsystems

If one component fail , the performance of

system will decrease.


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Example of parallel system reliability

If a System with two Subsystems (each

Subsystem works 85% of tested reliability) the

reliability of it will be: R Sys= 1-{(1-R Subsys1) x (1-R Ssubsys2)

=1-{(1-0.85) x (1-0.85)} =0.9775


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Importance of reliability

Reputation. A company's reputation is very closelyrelated to the reliability of its products. The morereliable a product is, the more likely the company is to

have a favorable reputation.

Customer Satisfaction. While a reliable product maynot dramatically affect customer satisfaction in apositive manner, an unreliable product will negativelyaffect customer satisfaction severely. Thus highreliability is a mandatory requirement for customersatisfaction.


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Warranty Costs. If a product fails to perform itsfunction within the warranty period, the replacementand repair costs will negatively affect profits, as well asgain unwanted negative attention.

Competitive Advantage. Many companies will publishtheir predicted reliability numbers to help gain anadvantage over their competitors who either do notpublish their numbers or have lower numbers.


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Reliable Brands- Laptops


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Reliable Brands- Laptops

http://www.pcworld.com/article/211402/reliability_and_service_laptops.html
http://www.pcworld.com/article/211402/reliability_and_service_laptops.htmlhttp://www.pcworld.com/article/211402/reliability_and_service_laptops.html


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Reliable Brands-Cars


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Reliable Brands-Cars


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Improving Reliability

Companies can improve their products by applying or improvingthese steps:

Component design: the right design for the component canenhance reliability.

Testing: testing reliability in different modes , different times ,different atmospheres will lead to improve the product and thereliability.

Redundancy/backups: thats mean system can work more thanone way , backup solution also improve the reliability

Preventive maintenance procedures: reliability improvementincrease with the preventive maintenance implementation.

User education: when the product users train or educate for howto use the product professionally thats will raise the reliability ofthe product.


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Reliability Standards

There are numerous standards for devicereliability.

activities have increased recently toward theadoption of international standards from theviewpoint of eliminating import-export barriersand technical obstacles for international trade.

standardization committees both domesticallyand in the U.S. and Europe, and promotesvigorous standardization activities.


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Reliability Standards

organizations

ISO International Standard Organization

JIS Japanese Industrial Standard

BS British Standard

MIL Military Standard ( U.S department of defense)

RCJ Reliability Center for Components of Japan

ANSI American National Standards Institute

CEN Comite Europen de Normalisation


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THANK YOU

Presentation 1 Final Reliability

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