1. Karpagam Institute of Technology
Coimbatore-105
Department of Mechanical Engineering
Course Code with Name: ME8097 –Non Destructive Testing and
Evaluation
Staff Name/Designation: VIJAYAN S N/AP
Department: Mechanical Engineering
Year/Semester: IV/VII
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2. Course Syllabus
UNIT I OVERVIEW OF NDT 9
NDT Versus Mechanical testing, Overview of the Non Destructive Testing Methods for the detection of
manufacturing defects as well as material characterisation. Relative merits and limitations, Various
physical characteristics of materials and their applications in NDT., Visual inspection – Unaided and
aided.
UNIT II SURFACE NDE METHODS 9
Liquid Penetrant Testing - Principles, types and properties of liquid penetrants, developers, advantages
and limitations of various methods, Testing Procedure, Interpretation of results. Magnetic Particle
Testing- Theory of magnetism, inspection materials Magnetisation methods, Interpretation and
evaluation of test indications, Principles and methods of demagnetization, Residual magnetism.
UNIT III THERMOGRAPHY AND EDDY CURRENT TESTING (ET) 9
Thermography- Principles, Contact and non contact inspection methods, Techniques for applying
liquid crystals, Advantages and limitation - infrared radiation and infrared detectors, Instrumentations
and methods, applications. Eddy Current Testing-Generation of eddy currents, Properties of eddy
currents, Eddy current sensing elements, Probes, Instrumentation, Types of arrangement,
Applications, advantages, Limitations, Interpretation/Evaluation.
UNIT IV ULTRASONIC TESTING (UT) AND ACOUSTIC EMISSION (AE) 9
Ultrasonic Testing-Principle, Transducers, transmission and pulse-echo method, straight beam and
angle beam, instrumentation, data representation, A/Scan, B-scan, C-scan. Phased Array Ultrasound,
Time of Flight Diffraction. Acoustic Emission Technique –Principle, AE parameters, Applications
UNIT V RADIOGRAPHY (RT) 9
Principle, interaction of X-Ray with matter, imaging, film and film less techniques, types and use of
filters and screens, geometric factors, Inverse square, law, characteristics of films - graininess, density,
speed, contrast, characteristic curves, Penetrameters, Exposure charts, Radiographic equivalence.
Fluoroscopy- Xero-Radiography, Computed Radiography, Computed Tomography
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3. Course Objective
To study and understand the various Non Destructive
Evaluation and Testing methods, theory and their
industrial applications.
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4. Course Outcome
• Explain the fundamental concepts of NDT
• Discuss the different methods of NDE
• Explain the concept of Thermography and
Eddy current testing
• Explain the concept of Ultrasonic Testing and
Acoustic Emission
• Explain the concept of Radiography
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5. Program Outcomes
1. An ability to apply knowledge of mathematics and engineering sciences to
develop mathematical models for industrial problems.
2. An ability to identify, formulates, and solve complex engineering problems.
with high degree of competence.
3. An ability to design and conduct experiments, as well as to analyze and
interpret data obtained through those experiments.
4. An ability to design mechanical systems, component, or a process to meet
desired needs within the realistic constraints such as environmental, social,
political and economic sustainability.
5. An ability to use modern tools, software and equipment to analyze
multidisciplinary problems.
6. An ability to demonstrate on professional and ethical responsibilities.
7. An ability to communicate, write reports and express research findings in a
scientific community.
8. An ability to adapt quickly to the global changes and contemporary practices.
9. An ability to engage in life-long learning.
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6. Program Specific Outcomes
• An ability to identify, analyze and solve engineering
problems relating to mechanical systems together
with allied engineering streams.
• An ability to build the nation, by imparting
technological inputs and managerial skills to become
Technocrats and Entrepreneurs, build the attitude of
developing new concepts on emerging fields and
pursuing advanced education.
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9. UNIT I: Topics
• NDT Versus Mechanical testing.
• Overview of the Non Destructive Testing
Methods for the detection of manufacturing
defects as well as material characterization.
• Relative merits and limitations.
• Various physical characteristics of materials
and their applications in NDT.
• Visual inspection – Unaided and aided.
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10. Video and Animation
• https://www.twi-global.com/technical-knowledge/faqs/what-
is-non-destructive-testing
• https://www.youtube.com/watch?v=e6r7G1rle2o
• https://forcetechnology.com/en/non-destructive-testing-ndt
• https://onlinecourses.nptel.ac.in/noc20_mm07/preview
• https://sites.google.com/view/alahijazi/classes/non-destructive-
testing-ndt
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11. Assignment Questions
1.Compare the destructive testing methods and non-destructive testing
methods with respect to advantage, limitation and on its application.
2.Demonstrate the comparison between destructive and Non-destructive
test.
3.Explain with suitable sketch about the Casting defects during casting
process.
4.Illustrate the working principle of VT with suitable sketch.
5. Describe the condition for non destructive testing
6. Write short about the non destructive testing methods and the
application of each techniques.
7. Summarize the various non destructive methods which is used for
detect the material defect.
8. Explain With the case study discuss the application of visual inspection
process.
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14. Introduction
What is NDT?
• NDT Stands for Non Destructive Testing
• Non Destructive Testing means testing of materials without destroying them.
• It is an examination of an object which will not produce any kind of damage
or destruction to the sample
Definition
Non Destructive Testing it is the process of inspecting, testing or
evaluating materials, components or assemblies for discontinuities or
differences in characteristics without destroying the serviceability of the part
or system
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15. • Materials sorting
• Materials characterization
• Property monitoring
• Thickness measurement
• Defect detection / location
• Defect characterization
• To detect internal or surface
flaws
• To measure the dimensions
of the specimen
• To determine material
structure or chemistry
• To evaluate material’s
physical or mechanical
properties.
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Objectives of NDT
16. Uses of NDT Methods
• Flaw detection / evaluation
• Leak detection
• Location measurements
• Dimensional measurements
• Structure and microstructure characterization
• Estimation of mechanical and physical properties
• Stress-strain and dynamic response measurement
• Material sorting
• Chemical composition determination
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17. Purpose of Materials Testing.
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• To determine and Evaluate various properties of materials both
quantitatively and qualitatively .
• To detect and evaluate surface or sub surface defects in raw
materials or processed parts.
• To check chemical composition.
• To determine the suitability for a material for a particular
application.
• To predict the strength and serviceability of the materials.
20. Destructive Testing
• In this type of testing, the component or specimen to be tested
is destroyed and cannot be reused.
• After testing, the component or specimen either breaks or
remains no longer useful for future use.
• As the name suggests, destructive testing (DT) includes
methods where the component or specimen is broken down in
order to determine physical and mechanical properties such as
strength, toughness, ductility and hardness.
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21. 21
Destructive testing is more suitable and economical for mass
production, as the cost of destroying a small number of pieces is
negligible. It is not economical to do destructive testing where
only one or very few items are to be produced.
Example:
Tensile test
Bending test
Fatigue test
Creep test
Torsion test
Hardness test
Impact test
Chemical analysis, etc
22. Overview of Destructive Testing
• Tensile Test
• Compression Test
• Hardness Test
• Impact Test
23. Tensile Testing is a form of tension testing and is a destructive
engineering and materials science test whereby controlled tension is
applied to a sample until it fully fails.
This is one of the most common mechanical testing
techniques. It is used to find out how strong a material is and also
how much it can be stretched before it breaks. This test method is
used to determine yield strength, ultimate tensile strength, ductility,
strain hardening characteristics, Young's modulus and Poisson's ratio.
Tensile Testing
24. 24
• Uses an UTM to apply
measured force to an test
specimen. The amount of
extension can be measured
and graphed.
• Variables such as strain,
stress, elasticity, tensile
strength, ductility and shear
strength can be gauged.
• Test specimens can be round
or flat.
Universal Testing Machine
28. Compression Test
Compression testing is one of the most fundamental types of
mechanical testing, alongside tensile and flexion tests. Compression tests
are used to determine a material’s behavior under applied crushing loads,
and are typically conducted by applying compressive pressure to a test
specimen (usually of either a cuboid or cylindrical geometry) using
platens or specialized fixtures on a universal testing machine.
During the test, various properties of the material are calculated
and plotted as a stress-strain diagram which is used to determine qualities
such as elastic limit, proportional limit, yield point, yield strength, and,
for some materials, compressive strength.
29. 29
Materials that exhibit high tensile strength tend to (but do
not always!) exhibit low compressive strength. Likewise, materials
high in compressive strength tend to exhibit low tensile strength.
Therefore, compression testing is often used on brittle materials
such as concrete, metals, plastics, ceramics, composites, and
corrugated materials like cardboard. These materials are often used
in a load-bearing capacity where their integrity under compressive
forces is critical.
31. Hardness Test
• Hardness may be defined as the ability of material to resist
indentation, scratching, abrasion.
1. Brinell Hardness test
2. Rockwell Hardness test
3. Vickers Hardness test
32.
33.
34. The Rockwell scale is a hardness scale based on indentation
hardness of a material. The Rockwell test measuring the depth of
penetration of an indenter under a large load (major load) compared
to the penetration made by a preload (minor load)
39. 39
The Izod impact strength test is an ASTM standard
method of determining the impact resistance of materials.
A pivoting arm is raised to a specific height
(constant potential energy) and then released. The arm swings
down hitting a notched sample, breaking the specimen. The
energy absorbed by the sample is calculated from the height the
arm swings to after hitting the sample. A notched sample is
generally used to determine impact energy and notch sensitivity.
41. 41
The Charpy impact test, also known as the Charpy V-
notch test, is a standardized high strain-rate test which
determines the amount of energy absorbed by a material
during fracture.
Absorbed energy is a measure of the
material's notch toughness. It is widely used in industry, since
it is easy to prepare and conduct and results can be obtained
quickly and cheaply. A disadvantage is that some results are
only comparative
43. Basic Elements of NDT
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•Source of probing medium
•Detector
•Recorder
•Interpretation
44. 44
Source of probing medium
The source or probing medium can be liquid
penetrate, magnetic particle, ultrasonic wave, radiation etc…
Detector
A Sensitive detector or sensor which is capable of
detecting the changes in probing medium
Recorder
A recorder or indicator is used to indicate or record the
response from the detector.
Interpretation
Various means of interpreting the recorded results
through peaks, graphs, bar diagrams etc…
45. Overview of Non Destructive Testing
• Visual Inspection
• Liquid penetrate test
• Magnetic particle test
• Thermography test
• Eddy current test
• Ultrasonic test
• Acoustic emission test
• Radiography test
46. Advantages of NDT
46
The equipments are easy to handle
Defects can be detected without damaging the components
Methods are quick and accurate
Components can be sorted out on the basis of electrical,
magnetic or chemical properties
Test results and other information can be conveniently recorded
on paper films, cassettes, floppies, DVD, CD. etc
47. Application of NDT
47
To ensure product integrity and reliability
To control manufacturing processes
To lower production costs
To maintain a uniformity in quality level NDT tests can be
performed …
(i) During manufacturing
(ii) After manufacturing
(iii) Even on parts that are already in service
48. Features of NDT
48
Using NDT, an entire production lot can be inspected, or
selected samples can be inspected
Also different tests can be applied to the same item, either
simultaneous or sequentially, and the same test can be
repeated on the same specimen for additional verification.
It may be added that the NDT equipment is often portable.
This permits the use of NDT methods for on-site testing in
most locations.
NDT does not permanently alter the specimen being inspected,
it is a high valuable technique that can save both time and
money in product evaluation, trouble shooting, and research
NDT make components more reliable, safe and
economical.
49. Visual Inspection
• Visual inspection is commonly defined as the examination of a
material, component, or product for conditions of non
conformance using light and the eyes, alone are in conjunction
with various aids. (shaking, listening, feeling and sometimes
even smelling)
• Digital detectors and computer technology have made it
possible to automate some visual inspection.
50. 50
It cannot detect certain minute flaws regardless of how keen
an eye or how much experience an analyst has. Even the use of
visual aids and tools is sometimes insufficient—and even minor
defects may develop into critical problems if overlooked for too
long. Where visual inspection can play a role is for monitoring
existing imperfections or as an initial tool for a very basic
inspection.
Visual inspections are inexpensive and require less
training than other testing methods. However, the discipline
simply cannot compare to the advanced flaw detection and
comprehensive scanning capabilities of advanced NDT
equipment.
51.
52. 52
Visual inspection (VI) is the oldest and most common
nondestructive testing method, but it doesn’t offer the same cutting-
edge technology and specialized techniques
Visual inspection experts maintain that visual aids such as
those listed below can enhance VI testing quality:
•Magnifiers
•Telescopes
•Microscopes
•Fiber-optic instruments
•Endoscopes
53. Applicability & Principle
Applicability
• To detect surface characteristics such as finish, scratches,
cracks & color.
• To check stain in transparent materials.
• To inspect corrosion.
Principle
• The test specimen is illuminated and the test surface is
observed and examined. Whenever required, the optical aids
such as mirrors, magnifying glasses, microscopes, video
cameras and computer vision system can employed.
54. Advantage
• Simple to use
• Relatively inexpensive
• Testing speed is high
• Testing can be performed on components which are in service
55. Disadvantages
• Test result is depends on skills and knowledge of tester.
• Eye resolution is weak
• Eye Fatigue.
56. Application
• Checking surface condition of the components.
• Checking alignment of mating surface.
• Checking shape of component
• Checking evidence of leaking
• Checking internal side effects.
58. •It is a effective method of detecting surface defects in metals and
other non porous material surfaces.
•It can be effectively used for ferrous, non ferrous metals, non
porous, non metallic materials such as ceramics & glass.
59. Applicability & Principle
Applicability
1. To locate cracks, porosity and other defects that breaks the
surface as a material and has enough volume to trap and hold
the Penetrant material.
2. To inspect large areas very effectively and will work on most
porous materials.
Principle
The principle of liquid Penetrant test is that the liquid
penetrants are drawn into the surface flaws such as cracks or
porosities by capillary action. Then the developer material in
conjunction with visual inspection reveals the surface flaws.
60. Merits and Demerits
Merits
• Sample and easy to use
• Inexpensive and versatile
• Highly portable
• Highly sensitive to fine, tight discontinuities
• Applicable to variety of material.
• Applicable to complex shapes.
Demerits
• It can only detect flaws that are open to surfaces
• It can not be used for porous and very rough surfaces
• It is required to remove all penetrant material after testing
61. Application
• Inspection of tools and dies
• Inspection of tanks, vessels, reactor, piping, dyers and pumps
in chemical, petrochemical, food, paper and processing
industry.
• Inspection of diesel locomotive, truck and automobile parts.
• Inspection of aircraft engine parts.
63. Magnetic Particle Testing
• Magnetic Particle testing is used for testing of materials which
can be easily magnetized.
• This method is capable of detecting surface and subsurface
flaws such as cracks and inclusion.
• This method is used for ferromagnetic materials (iron, steel,
nickel and cobalt alloys)
• It is free from any restriction as to size, shape & composition
64. Principle
• When ferromagnetic material is magnetized will have a
distorted magnetic field in the vicinity of flaws and defects.
• The flaws are revealed by the application of iron powder in
suspension with liquid. The magnetic particle are strongly
attracted to surface region where the flux is concentrated.
• This would create a visual indication approximating the size
and shape of flaws.
65. Advantage
• Relatively simple and fast
• Reveals both surface and subsurface flaws
• Easy to portable
• Applicable to complex geometries.
66. Limitations
• Applicable to only ferromagnetic materials.
• After testing the part must be demagnetized and cleaned.
• High current source is required.
• Paint / other non magnetic covering affecting sensitivity.
67. Application
• Inspection of fans and blowers in thermal power plant.
• Inspection of weld cracks
• Inspection of connecting rod.
• Pipeline and ship structures.
68. Thermography Testing/ Thermal Imaging /
IR Thermography.
https://www.youtube.com/watch?v=J0y-zPaqcvs
• Technique that allows the visualization of heat pattern on an
object.
• Thermography enables the thermal profile of material or
component to be presented in a graphic form which allows a
working temperature assessment to be derived from this
variation in the material/ component temperature are identified
using which the flaws are detected.
70. Principle
• The basic principle of thermal involves the measurement or
mapping of surface temperatures when heat flows from, to or
through a test objects. Temperature differentials on a surface or
change in surface temperature with time are related to heat
flow patterns. This heat flow pattern can be used to detect
flaws.
71. Advantages
• The non contact test method can be used from a safe distance.
• Visible picture of component is possible.
• Permanent record is possible.
• IR Cameras are easy to use.
• The exact location of the defects can be determined.
72. Demerits
• Interpretation of results need experience
• Higher accuracy is not possible due to emissivity of different
materials.
• Cost of equipment is high.
73. Applications
• Inspection of defects in composites.
• Inspection of impact defects in CFRP.
• Detection of defects in turbine components.
• Detection of corrosion in aircraft parts.
76. Eddy Current Testing
• Eddy current testing is an electromagnetic NDT Technique.
• Used only electrical conducting materials.
Principle
Eddy current are induced in a test object by bringing it close to an
alternate current carrying coil.
The eddy currents are normally parallel to the coil windings the defects
in the test object impede and change the direction of eddy current and
cause change in the direction of electromagnetic field.
These changes affects the inspection coil , the voltage of which is
monitored to determine the presence of defects.
77. Advantages
• It is quick to use and provides immediate results.
• No physical contact required
• It can be automated
• Low cost and portable.
• Pre and Post treatment of test objects are not required.
78. Disadvantages
• Its depth of penetration is limited to 8 mm
• Constant separation distance between coil and the specimen is
required for good results.
• Only applicable to conductive metals.
• High skilled operator is required.
79. Applications
• Detection and measurements of flaws in steering mechanism,
landing gears, engine parts, aircraft wheel, aircraft wing
structure.
80. Ultrasonic Testing
Uses sound energy to determine the integrity of the test objects.
High frequency ultrasonic waves 0.5-20 MHz
81. Basic Principles of Ultrasonic Testing
81
Ultrasonic Testing (UT) uses high frequency sound energy to
conduct examinations and make
measurements. Ultrasonic inspection can be used
for flaw detection/evaluation, dimensional measurements,
material characterization, and more. To illustrate the general
inspection principle, a typical pulse/echo inspection configuration
as illustrated below will be used.
82. 82
A typical UT inspection system consists of several functional
units, such as the pulser/receiver, transducer, and display devices. A
pulser/receiver is an electronic device that can produce
high voltage electrical pulses. Driven by the pulser,
the transducer generates high frequency ultrasonic energy.
The sound energy is introduced and propgates through the
materials in the form of waves. When there is a discontinuity (such
as a crack) in the wave path, part of the energy will be reflected back
from the flaw surface.
83. 83
The reflected wave signal is transformed into an electrical
signal by the transducer and is displayed on a screen. In the applet
below, the reflected signal strength is displayed versus the time
from signal generation to when a echo was received. Signal travel
time can be directly related to the distance that the signal traveled.
From the signal, information about the reflector location,
size, orientation and other features can sometimes be gained.
84. Advantages of Ultrasonic
Inspection
84
•It is sensitive to both surface and subsurface discontinuities.
•The depth of penetration Penetration (Ultrasound) - Propagation of ultrasonic
energy into a material. See also effective penetration. for flaw detection or
measurement is superior to other NDT methods
•Only single-sided access is needed when the pulse-echo technique is used.
•It is highly accurate in determining reflector position and estimating size and
shape.
•Minimal part preparation is required.
•Electronic equipment provides instantaneous results.
•Detailed images can be produced with automated systems.
•It has other uses, such as thickness measurement, in addition to flaw detection
85. Limitations
85
•Surface must be accessible to transmit ultrasound.
•Skill and training is more extensive than with some other methods.
•It normally requires a coupling medium to promote the transfer
of sound energy into the test specimen.
•Materials that are rough, irregular in shape, very small,
exceptionally thin or not homogeneous are difficult to inspect.
•Cast iron and other coarse grained materials are difficult to inspect
due to low sound transmission and high signal noise
•Linear defects oriented parallel to the sound beam may go
undetected.
86. Applicability
• Detection of flaws in materials
• Measurement of thickness.
• Determination of mechanical properties and grain structure of
materials.
