Fault tree analysis, Computer Networking


Reliability engineering, in a nutshell is concerned with failures.   How failures occur, how often they occur, and how to minimize them are the basic problems. It can be seen very easily that each and every failure has a cause behind it. It is an effect of some change in the parameter of a component or system. It may be a result of poor material, wrong manufacturing technique, improper design or the presence of some other unwanted signal in the system. Finding the real or root cause of a failure is one of the most important aspects of reliability engineering. This is a real challenge to the engineers associated with reliability.

The  fault  -  tree  technique  as  analyse  complex  systems.  It  is  based  upon deductive reasoning. This provides a concise and orderly description of the various combinations of possible occurrence within the system, which can result in a predetermined critical output event.

A fault tree is a diagrammatic representation of all possible fault events, their logical combinations, and their relationship to the system failure. The system fault is normally represented at the top of the tree and faults at the lowest, basic level at the bottom. The events at the lowest level are known as "basic events". Events resulting from the combination of basic events are known as "intermediate events". The failure probabilities of  basic events are combined to obtain the failure probabilities of intermediate events and finding the top event, the system failure. Logical "AND" and "OR" gates are used to combine two or more events

Fault tree can be used for both qualitative as well as quantitative reliability analysis. In qualitative analysis, fault - tree can help in tracing the cause of a specific failure and can effectively locate the root of the basic problem. In quantitative  analysis,  fault  tree  can  help  in  evaluating  the  probability  of occurrence of a particular event from all the possible failure causes.  Probability of occurrence of basic events are evaluated from previous reliability data and are combined using AND and OR gates to get the higher events probability.

Fault tree methods can be applied in the early design phase, and then progressively refined and updated as the design evolves to track the probability of  an  undesired  event.  Initial  fault  tree  diagrams  might  represent  functional blocks, becoming more definitive at lower levels as the design materializes in the form of specific parts and materials.


The fault tree itself is a graphical model of the combinations of various parallel and sequential fault events that will result in the occurrence of the undesired event. The faults can be events associated with component hardware failures or human errors, any other pertinent events which can lead to the undesired event.

Before constructing the fault tree we must have a detailed functional block diagram  of  the  system.  The  functional  block  diagram  of  the  system  and equipment must clearly define the critical failure mode in terms of the system level malfunction or symptom to be avoided.


The fault-tree logic diagram is constructed relating all possible sequences of events whose occurrence would produce the undesired events identified in the functional block diagram.  The fault tree should depict the paths that lead to each higher level in the functional configuration.

In some cases it may be necessary to construct fault trees for each possible operating mode, function or mission event in the mission sequence. The accuracy of a fault tree is highly dependent on the analyst. Unlike the parts list available in FMECA there is no means of checking back to make sure that a significant potential failure contribution has not been overlooked.


Posted Date: 9/7/2012 8:13:11 AM | Location : United States

Related Discussions:- Fault tree analysis, Assignment Help, Ask Question on Fault tree analysis, Get Answer, Expert's Help, Fault tree analysis Discussions

Write discussion on Fault tree analysis
Your posts are moderated
Related Questions
#question.what can we do with a spider when it red?.

Physical layers defines with synchronizing the 1s and 0s on the wire.

What is the juncture at which the CPE ends and the local loop portion of the service starts?  Ans) The demarcation or demarc is the juncture at which the CPE ends and the local

The disadvantages and advantages of Private and Public networks are shown in the table below:

Q. Define layered network model? - The OSI Reference Model is collection of seven layers every specifying particular network functions. - The process of breaking up the func

What is multicast routing? Sending a message to a group is known as multicasting, and its routing algorithm is known as multicast routing.

Error detection and correction The digital traffic stream of second generation systems also lends itself to the use of error detection and correction methods. The result can be

Retransmission of packets The disadvantage  of thronging away a correctly received packet is that  the subsequent retransmission  of the  packet might  be lost  or garbled and

What is Microwave? Microwaves have been used in data communications. Microwave has a higher frequency than radio waves and thus can handle larger amounts of data.