MS05 question 3

Explain BATH-TUB curve and Tero-Technology.

The bathtub curve is a concept that is used for describing particular forms of hazard functions which are decreasing failure rate, constant failure rate and Increasing failure rate. It has a wise usage in the field of reliability engineering and is derived from human life.

Whereas Terotechnology is the technology that studies the costs associated with assets throughout their lifecycle. This technology was developed with the aim of reducing different costs that are incurred from the acquisition of an asset to its disposal and also develops methods for extending the working life of the asset.
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RELIABILITY SPECIALISTS
often describe the lifetime of a population of products using a graphical representation called the bathtub curve. The bathtub curve consists of three periods:
1.an infant mortality period with a decreasing failure rate
2.followed by a normal life period (also known as “useful life”) with a low, relatively constant failure rate and
3.concluding with a wear-out period that exhibits an increasing failure rate.
DRAW A BATHTUB SHAPED CURVE.
describes the relative failure rate of an entire population of products over time. Some individual units will fail relatively early (infant mortality failures), others (we hope most) will last until wear-out, and some will fail during the relatively long period typically called normal life. Failures during infant mortality are highly undesirable and are always caused by defects and blunders: material defects, design blunders, errors in assembly, etc. Normal life failures are normally considered to be random cases of “stress exceeding strength.” However, many failures often considered normal life failures are actually infant mortality failures. Wear-out is a fact of life due to fatigue or depletion of materials (such as lubrication depletion in bearings). A product’s useful life is limited by its shortest-lived component. A product manufacturer must assure that all specified materials are adequate to function through the intended product life.
the curve at the start depicts

TYPES OF FAILURE
Early Life Failures
• large number of new component failures which
decreases with time
•Useful Life Failures
• small number of apparently random failures during
working life
•Wear-out Failures
• increasing number of failures with time as
components wear out
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MEASURING UNRELIABILITY
= failure rate
= number of failures
unit time
- typically failures per year
constant in useful life period
- data collection / processing simple
- defines "bath-tub" curve
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EARLY LIFE PERIOD
• substandard weak specimens
• often caused by poor / variable manufacturing
and poor quality control
• prevented by effective quality control, burn-in,
and run-in, de-bugging techniques
• weak components eventually replaced by good ones
• probabilistic treatment less important
© University of Newcastle upon Tyne
USEFUL LIFE PERIOD
• random or chance failures
• caused by unpredictable sudden stress accumulations
outside and inside of the components
beyond the design strength
• over sufficiently long periods frequency of occurrence
is approximately constant
• failure rate used extensively in
Safety & Reliability analyses
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THE BATHTUB CURVE AT THE CENTRE
A BIG STRETCH DEPICTS THE



USEFUL LIFE PERIOD
defined by exponential or Poisson distribution
reliability R(t) = e- t
R(t) = probability that device will not fail in time t
= failure rate = number of failures
unit time
reciprocal 1 / = m = Mean Time Between Failures

- expected number of failures in time t is the same
for any equally long operating period
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USEFUL LIFE PERIOD
- chance of survival after m (10 years) = 36.8%
say 1 failure in 10 years, = 0.1, m = 10
- chance of failure after m (10 years) = 63.2%
- chance of survival after 1% of m (1 month) is 99%
- chance of survival after 10% m (1 year) is 90.5%
- chance of survival after 50% m (5 years) is 60.6%
- chance of survival after 90% m (9 years) is 40.7%
- chance of survival after 200% m (20 years) is 13.5%
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THE BATHTUB CURVE AT THE END
-A SHORT STRETCH DEPICTS THE





WEAR-OUT FAILURE PERIOD
• symptom of component ageing
• failures cluster around Mean Wear-Out Life M
• Mean Wear-Out Life M usually much shorter
than MTBF m
• Wear-out failure distribution approximates
to Normal Distribution with mean M
and standard deviation o
• prediction is important for replacement
and maintenance policy
© University of Newcastle upon Tyne
WEAR-OUT FAILURE PERIOD

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APPLICATION TO
CHEMICAL PLANTS
• are failures random?
• does reported data include early-life
and wear-out failures?
• how does maintenance policy affect
observed failure rate?
• can we predict the failures - useful life period?
or is failure rate rising / falling with time?
•can Weibull distribution help us?
f(t) - 1 - exp (-t/A)^B
•shape parameter B<1 decreasing failure rate
•if B>1, increasing failure rate
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YOUR NEW CAR.....…!
want 3 years operation with 99% reliability?
t = 3 years, exp(-lt) = 0.99,
so failure rate l = 0.00335
ie m (mean time between failures) = 1/ l = 298 years
NOTE the car doesn't last this long before breaking down!
- why?
Useful Life failure rate is an "Instantaneous Failure Rate"
- wear-out M takes over after 5 to 10 years!!

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TERO TECHNOLOGY IS A TOTAL FACILITY MANAGEMENT
OF ENGINEERING SOLUTIONS.

TERO Technology's experts team that caries out the daily operations of Facilities Management Services for the clients. It helps to optimize the assets with professional Facilities Management and Operation & Maintenance (O&M) Services for Mechanical & Electrical (M & E) Systems, Civil Works, Landscape, Janitorial and other facility specialization. Rather than bearing addition business burdens, a 'single point responsibility' through direct maintenance, subcontract & vendor management will save time, money and effort.

TERO Total Facilities Management handles various kinds of Facilities, including:
Commercial Buildings
Healthcare Facilities / Operation Theatre
Information & Communication Technology Centers
Manufacturing Facilities / Clean Room technology
Telecommunication infrastructure.
Transportation Support Infrastructure
(ports, airports, railway stations, etc)
Asset Management

TERO offers a seamless, independent and total management of the customers' asset portfolio where they finance, procure, implement, maintain and finally transfer the assets to the customer on mutually agreed terms. Close interactions with the clients' Chief Financial Officer results in amazing financial savings. And most importantly they completely relieve the organization of the initial financial and administrative burden.

The benefits bought to our clients include:
Transfer of ownership of Control and Risk Management, Analysis

Reporting, Implementation & Coordination, Defining & Planning

One-Stop project management and total engineering services form project inception to steady state operations

*Re-engineering of engineering and maintaining the organization work process.
*Helping to reducing the costs --expenses / capital.
*Establishing and maintaining safety, health and environment and managing
the quality assurance / risk management program.
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