Engineering Failure Analysis

7/27/2019 Engineering Failure Analysis

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Engineering Failure Analysis

Amena JalilJunior EngineerNational Centre for NDT (NCNDT)


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Engineering Products and Their

Performance

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Main stages in the history of an engineering product


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Engineering Products and Their Performance Contd

Engineering design is essentially a decision making

process .

(i) geometry and dimensions of different parts, (ii)

types of materials used in manufacturing and their

specifications, (iii) fabrication and assembling

techniques, and (iv) service conditions.

Design is initiated after establishing the market needfor a new product or improving the performance of

an existing product.

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Engineering Products and Their Performance Contd

Following this stage, the design is materialized into a

commercial product by the manufacturer.

Finally, the product is put into service to meet its

functional requirements specifying the procedures of

start-up and shut down as well as the maintenance

procedure and its schedule.

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Failure of Engineering Products When an engineering product ceases to perform one

or more of its functions well before its expected

service life, it is said to fail.

Failures can cause loss of lives, unscheduled shut

downs of plants, increasing maintenance and repair

costs as well as very costly litigation and damages .

Weakest link in the chain.

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Definition and Objective of Failure

Analysis Investigations

To determine the cause of failure of a certain

product.

Findings are documented in a report. Results of failure analysis investigations can be

extremely useful to designer s of the same or

similar products.

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Definition and Objective of Failure Analysis

Investigations Contd

Manufacturers can also use the results of failure

analysis investigations for marketing purposes to

promote a new product with better performance

capabilities.

Furthermore, by identifying the deficiencies of

certain structural materials through failure analysisinvestigations, it is possible to develop new materials

or improve the properties of existing materials.

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Typical Defects

Material imperfections, defects generated

during service, and defects introduced as a

result of faulty design practice. Defects can be found within the original

material supply or can be introduced during

the manufacturing process.

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Failure Analysis Procedure

Dependent upon the particular case.

1. What is the mode of failure?

2. What is the most probable cause of failure?

3. How can failure be prevented in the future?

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Failure Analysis Procedure Contd

Any effective failure analysis investigation

must involve three main stages:

(i) clear definition of the problem(ii) complete search of the literature

(iii) development of an experimental program

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Definition Of The Problem

Analyst meets with concerned personnel such as

process engineers, maintenance engineers, etc. to

discuss the problem.

Ask questions..

Inspection of failure site.

Photographic documentation of the failed

component.

Depth of information obtained, site inspection, as

well as the skill and judgment of the analyst.

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Failure analysis of PSV springs of 17-4PH

stainless steel

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Methodology

Chemical analysis

Examination of the fractures.

Microstructural examination

Hardness measurements.

Observation of the cracking surfaces in the scanning electron

microscope .

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Engineering Failure Analysis

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