Understanding of Reliability Engineering
Chapter 1: Introduction
The reliability engineering uses
engineering concepts and its rules that is related with time. This is one of
systematic approach of determining products or systems reliability that takes
place during its life cycle. The industry that produces the system and products
requires reliability engineering. The reliability engineering also deals with
the improvement of understanding areas of pinpointing product. The failure
isn’t canceled by the use of reliability but is to pinpoint the possibility of
failure of system and products. This also gives the way to mitigate these
actions to another.
The evaluation using reliability
has number of analysis which vary with the phase of system and its life cycle. The
design of system and changes could be made after the through reliability
analysis. The engineer required for this analysis are quality engineer, design
engineer, test engineer and reliability engineer. The industry requires
reliability for following reasons and they are: Company’s Reputation,
Satisfaction of customers, Cost of warranty, Analysis of cost and requirement
of customers.
This paper gives the detail brief
of reliability engineering and focuses on its current development of analyzing
risk. In the modern industry and its technologies, it is found to be most
fundamental aspect. As stated above reliability provides quantification on
possibility of system failure and also gives protective measures. The number of
components has equipped with the barrier that protects it from being failed to
operate. These products could be system, software, hardware and human as well. The
main objective is to decrease the potentiality of failure of systems. The
approach that are being used in the early days are to identify all the possible
event sequence that gives raise to worst case. Another approach is to determine
consequences and make a framework for the safely barriers to prevent the
product from being failed.
The design of the products are
made to withstand all the above list that takes it to worse cases. With this
the industry could move to the way of unnecessary approach and barrier for the
products. The cost of products are found to be higher with this approach to illuminate
risk. As it is not useful in the modern technology of this world, the more
advanced and quantitative approach has been undertaken with more accurate
framework of design. It was earlier used in nuclear and aerospace as these
missions involve huge amount of investments. The probabilistic risk was being
used after brief research on this modern approach. The system safely has been
handled properly with this probabilistic risk analysis approach. All the other
sceneries are also taken into consideration with this approach which is not
limited to only occur cases.
The next section describes the
history of reliability engineering and its evaluation. The 3rd
chapter describes the current use of reliability engineering and a case study
of company. Similarly, the discussion part is about the complete discussion of
traditional approach and modern and how they differ.
Chapter 2: History
The reliability was introduced in the world in 1800s by
Samuel T. Coleride. The framework were used during the early ages and it grew
with the treatment of quantitative. The statistics and probability is the main
theory behind the reliability engineering and this has taken its place in
engineering. Mostly it was used in gambling and other purpose for prediction. At
early 1900, there took practical use of this concept of reliability that was on
the products. The industry needed this part of reliability to be implemented to
get better result and good benefits. The vacuum tube was developed and it has
number of failure which lead to research that included the reliability
engineering into action. The data of failure and its main cause where recorded
and on the next products, all these were taken care of. Specially, projects
that were funded by military first started this concept. As the result, it lead
to quantitative reliability.
The scientist and researchers in last two decades has found
that there has been stunning increase in the reliability engineering. Nowadays,
the modern economy has taken over the industry with better reliability of
products and systems. The products on the traditional approach were given more
value to products. On the other hand, today's approach gives value to the
performance and services provided by the products which has enhanced the
customer satisfaction. The industry has got its views changed over the decades
and it has led to more attention to services. The failure isn’t the main
concern but the services are.
The reliability engineering is one of the well-used and
multidisciplinary scientifically. There are mainly number of question are being
used to analysis the uncertainty and failure of products. The system failure is
being determined and its reliable system is being developed. Along with these
the design of system is most important along with its management.
Chapter 3: Case Study
The prediction of the reliability
of the products from the industry is one of major pre-case is undertaken. The
case study is based on the Hardware's Confidence interval and its prediction
for reliability. This has number of purpose during development life cycle. The
thermal stress as well as electrical effect can be observed using it during
design stage. When the products are ready reliability is used for setting up of
target on field. The field failure rate could differ from predicted to worse. This
can be overcome with the idea of providing free products to be failure products
by the company. In the case of warranty, similar procedure is undertaken
providing new products to the customers.
The reliability prediction is
required by the business that can be found in number of companies. Number of
models embraced this development on it. This chapter deals with the description
of reliability predication of the electronic systems. The company for the case
study is D-link for digital telephone switch, internet router etc.
Approach:
There are number of approaches
that are used for prediction of reliability. The sum of uncorrelated variables
are added with their variance is one of the common method. The computer aided
design is used to test all the condition that the processor could face and
might get damaged. These CAD program are platform for automatic condition
checking with manual instruction. There is database on this program that stores
the entire failure component's issue and has 96% of confidentiality rate. There
are number of other prediction that is followed with precise observation.
Modeling for reliability:
The reliability model is done
using subassembly that gives the description about product assembly. As the
number of small components are put together while assembling, it is found to be
easy to predict the reliability of final products. We obtain the equation for
lifetime variable for components and they are:
F(t)
= F1(t)…Fn(t) 3.1
and
h(t)=
h1(t)+…….+hn(t) 3.2
Here, The
distribution of life is being given by F and h. The equation is applicable with
independent components. There are two parts for the experiment that is
performed by D-link.
Circuits boards and its composition:
The above part
gives the description of product reliability prediction but here the new
circuit board is taken into consideration for the D-link company. There are
number of components on the circuit board and they are as given as
Microprocessors, gates, oscillator, Ram, and capacitors. These newly designed's
board's thermal analysis is taken and the table is given below for above
products.
Device
|
Board Location
|
Tut(c)
|
Microprocessor
|
IC 1
|
80
|
Gate
|
IC 2.4
|
65
|
Oscillator
|
Y 1
|
45
|
RAM
|
IC 3.1
|
45
|
Capacitor
|
C 1-C 50
|
40
|
Database of
Component failure:
This database is constructed for
the process of collecting all the information regarding failure of components.
Alone with this the thorough analysis is also done for rate of failure
calculation. The D-link takes the database collection in number of two stages.
There are 330 components on the board that were described above. After the data
collection is completed, there is thermal analysis undertaken for the
components. The analysis is done using thermal analysis tools and software.
Chapter 4: Discussion
Taking place at scientific discipline in 1900s, Reliability
engineering has taken critical place in industry that produces products. The
traditional approach used the all necessary measure for the product to be good
on the field and last long. This made the product more expensive and
unnecessary products were added as well. Nowadays, there are a lot of
challenges that the reliability engineering is facing. The software and the
tools have made it much easier to mitigate the failure of products. The
customers are provided with the new products upon failure. One of the examples
in the recent time could be taken as SAMSUNG note mobile phone. The field
failure by the battery has made the company to take back all these model of
products and provide refund to the customers. The field failure could get worse
and this is one of the real time examples.
The classic approach has been undertaken by modern
reliability analysis. The accident environment is created and simulated to test
the products and its extreme capability of withstanding these conditions. When
these are performed, number of equipment are taking close look over the
products and its temperature and other aspects as well. The framework by carlo,
takes the use of history of product and its failure report. This framework
makes analysis and sequences of event from the past history and design of the
product over the years along with the component changes.
Even with all these advanced technology, there is risk and
its challenge to reliability engineering.
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