Failure Modes and Effects Analysis (FMEA)

FMEA

Failure Mode and Effects Analysis (FMEA) was one of the first systematic techniques for failure analysis. It was developed by reliability engineers in the 1950

Failure modes and effects analysis (FMEA) is a step-by-step approach for identifying all possible failures in a design, a manufacturing or assembly process, or a product or service.

Causes of Failure

Failure causes are defects in design, process, quality or part applications, which are the underlay causes of failure are which initiate a process which leads to failure

Some types of mechanical failure mechanisms are:

fatigue ,ductile fracture, brittle fracture, impact, creep, wear, corrosion.

Methods of analysis

The failure analysis of many different products involves the use of the following tools and techniques:

MicroscopesOptical microscopeX-ray microscope

RadiographyNeutron RadiographyX-ray Radiography

Analysing cause of failure

Failure analysis is the process of collecting and analysing data to determine the cause of a failure. It is an important discipline in many branches of manufacturing industry.

It is a vital tool used in the development of new products and for the improvement of existing products.

There are many companies which provide services to find the cause of failure in products, devices .

The failure analysis process relies on collecting failed components for subsequent examination of the cause or causes of failure using a wide array of methods, especially microscopy and spectroscopy.

FAILURE MODES

Failure modes are the possible cause of failure may occur in a component which includes mechanical failure, functional failure ,design failure

Modes7

Failure Modes Fracture FatigueCreep

Fracture Modes DuctileBrittle

FRACTUREFracture is a separation of object or a

material in to two or more pieces under the action of stress.

Example : rectangular bar

FATIGUEFatigue is the weakening of a material caused

by repeatedly applied cyclic load.Examples of Fatigue FailuresDoor Stop:

CREEPCreep is defined as a permanent

deformation of a material under steady load with a function of time and temperature.

Example: Steam turbine blades

Ductile fracture: In ductile fracture extensive plastic

deformation (necking) take place before fracture

Brittle fracture: brittle fracture , no plastic deformation

takes place before fracture.

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Example: Pipe Failures

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• Ductile failure: -- one piece -- large deformation

• Brittle failure: -- many pieces -- small deformations

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Ductile & Brittle Failure

cup-and-cone fracture brittle fracture

Advantages:

• Improve the quality, reliability and safety of a product/process

• Improve company image • Increase user satisfaction• Reduce system development

time and cost• Collect information to reduce

future failures.• Reduce impact on company

profit margin• Improve production yield

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Uses:

• Development of system requirements that minimize the likelihood of failures.

• Development of designs and test systems to ensure that the failures have been eliminated or the risk is reduced to acceptable level.

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