Eddy current inspection is one of several NDT methods that use the principal of “electromagnetism” as the basis for conducting examinations.
Eddy currents are created through a process called electromagnetic induction. When alternating current is applied to the conductor, such as copper wire, a magnetic field develops in and around the conductor. This magnetic field expands as the alternating current rises to maximum and collapses as the current is reduced to zero. If another electrical conductor is brought into the close proximity to this changing magnetic field, current will be induced in this second conductor. Eddy currents are induced electrical currents that flow in a circular path. They get their name from “eddies” that are formed when a liquid or gas flows in a circular path around obstacles when conditions are right.
Eddy current inspection is one of several NDT methods that use the principal of “electromagnetism” as the basis for conducting examinations.
Eddy currents are created through a process called electromagnetic induction. When alternating current is applied to the conductor, such as copper wire, a magnetic field develops in and around the conductor. This magnetic field expands as the alternating current rises to maximum and collapses as the current is reduced to zero. If another electrical conductor is brought into the close proximity to this changing magnetic field, current will be induced in this second conductor. Eddy currents are induced electrical currents that flow in a circular path. They get their name from “eddies” that are formed when a liquid or gas flows in a circular path around obstacles when conditions are right.
Introduction to NDT and Visual Inspection Hareesh K
This presentation will gives you basic idea about Non destructive testing and brief detail about Visual Inspection Technique.This topic is included in UG level Mechanical Engineering Syllabus by all top Indian Universities
This presentation was developed to provide students in industrial technology programs, such as welding, an introduction to magnetic particle testing. The material by itself is not intended to train individuals to perform NDT functions but rather to acquaint individuals with the NDT equipment and methods that they are likely to encounter in industry. More information has been included than might necessarily be required for a general introduction to the subject as some instructors have requested at least 60 minutes of material.
Introduction to Nondestructive Testing
Visual Inspection
Penetrant Testing
Radiographic Testing
Ultrasonic Testing
Eddy Current Testing
Welder Certification
This presentation Based on Non Destructive Testing.the Abbreviation is NDT.Dye penetrant Testing (DPT) is the part of NDT .I think my presentation will be helpful for NDT Related person
Introduction to NDT and Visual Inspection Hareesh K
This presentation will gives you basic idea about Non destructive testing and brief detail about Visual Inspection Technique.This topic is included in UG level Mechanical Engineering Syllabus by all top Indian Universities
This presentation was developed to provide students in industrial technology programs, such as welding, an introduction to magnetic particle testing. The material by itself is not intended to train individuals to perform NDT functions but rather to acquaint individuals with the NDT equipment and methods that they are likely to encounter in industry. More information has been included than might necessarily be required for a general introduction to the subject as some instructors have requested at least 60 minutes of material.
Introduction to Nondestructive Testing
Visual Inspection
Penetrant Testing
Radiographic Testing
Ultrasonic Testing
Eddy Current Testing
Welder Certification
This presentation Based on Non Destructive Testing.the Abbreviation is NDT.Dye penetrant Testing (DPT) is the part of NDT .I think my presentation will be helpful for NDT Related person
Eddy Current Testing is one of the most widely used Non-destructive Testing techniques to detect flaws or defects inside a material. There are several different eddy current testing methods. Eddy Current Testing PDF guides about the various methods of Eddy Current Testing.
Eddy Current Metal Testing for ConservationJason Church
This powerpoint was presented as part of a workshop on Eddy Current Testing for Conservation at the annual metting of the AIC on May 19, 2009 Los Angeles, CA.
Non-destructive techniques are used in the metal industry and science in order to evaluate the properties of a wide variety of materials without causing damage. Some of the most common non-destructive techniques are electromagnetic, ultrasonic and liquid penetrant testing. One of the conventional electromagnetic methods utilized for the inspection of conductive materials such as copper, aluminum or steel is eddy current non-destructive testing .Electromagnetic methods such as eddy current, magnetic particle or radiographic and ultrasonic methods all introduce electromagnetic or sound waves into the inspected material in order to extract its properties. Penetrant liquid techniques can detect cracks in the test material by using either fluorescent or non-fluorescent dyes.
This presentation gives the information about introduction to control systems
Subject: Control Engineering as per VTU Syllabus of Aeronautical Engineering.
Notes Compiled By: Hareesha N Gowda, Assistant Professor, DSCE, Bengaluru-78.
Disclaimer:
The contents used in this presentation are taken from the text books mentioned in the references. I do not hold any copyrights for the contents. It has been prepared to use in the class lectures, not for commercial purpose.
This template was created for DSCE, Aeronautical students. You have to replace the institution details.
Create a separate document for each chapter, so that under numbering, you can change the sequence of chapter main heading according to chapter wise. i.e., 2.1, 2.2 etc.
Same procedure is applicable to Figure caption and Table caption.
This template can be used to generate, BE seminar report, M.Tech and Ph.D thesis also.
This template is created to assist UG students in generating their thesis without much hassle.
Contents are taken from VTU website. I don’t hold any copyright for this document.
Hareesha N G
Assistant Professor
DSCE, Bengaluru
This document is an Instruction manual for Computer aided machine drawing
Subject: Computer aided machine drawing (CAMD)
Syllabus contest is as per VTU, Belagavi, India.
Notes Compiled By: Hareesha N Gowda, Assistant Professor, DSCE, Bengaluru-78.
This document gives the class notes of Unit-8: Torsion of circular shafts and elastic stability of columns. Subject: Mechanics of materials.
Syllabus contest is as per VTU, Belagavi, India.
Notes Compiled By: Hareesha N Gowda, Assistant Professor, DSCE, Bengaluru-78.
This document gives the class notes of Unit-8: Torsion of circular shafts and elastic stability of columns. Subject: Mechanics of materials.
Syllabus contest is as per VTU, Belagavi, India.
Notes Compiled By: Hareesha N Gowda, Assistant Professor, DSCE, Bengaluru-78.
This document gives the class notes of Unit 6: Bending and shear Stresses in beams. Subject: Mechanics of materials.
Syllabus contest is as per VTU, Belagavi, India.
Notes Compiled By: Hareesha N Gowda, Assistant Professor, DSCE, Bengaluru-78.
This document gives the class notes of Unit 5 shear force and bending moment in beams. Subject: Mechanics of materials.
Syllabus contest is as per VTU, Belagavi, India.
Notes Compiled By: Hareesha N Gowda, Assistant Professor, DSCE, Bengaluru-78.
This document gives the class notes of Unit 3 Compound stresses. Subject: Mechanics of materials.
Syllabus contest is as per VTU, Belagavi, India.
Notes Compiled By: Hareesha N Gowda, Assistant Professor, DSCE, Bengaluru-78.
This document gives the class notes of Unit 2 stresses in composite sections. Subject: Mechanics of materials.
Syllabus contest is as per VTU, Belagavi, India.
Notes Compiled By: Hareesha N Gowda, Assistant Professor, DSCE, Bengaluru-78.
This document contains: Mechanics of Materials: Question bank from old VTU Question papers ; Pprepared by Hareesha N G, DSCE, Bengaluru. These questions are picked from last 06 years of old VTU question papers.
This presentation was prepared for a seminar. I have shared this with you. This is not related to curriculam. Please writre your criticisms to: hareeshang@gmail.com.
This presentation gives the information about Screw thread measurements and Gear measurement of the subject: Mechanical measurement and Metrology (10ME32/42) of VTU Syllabus covering unit-4.
This presentation gives the information about Force, Pressure and Torque measurements of the subject: Mechanical measurement and Metrology (10ME32/42) of VTU Syllabus covering unit-6.
This presentation gives the information about mechanical measurements and measurement systems of the subject: Mechanical measurement and Metrology (10ME32/42) of VTU Syllabus covering unit-5.
This CIM and automation laboratory manual covers the G-Codes and M-codes for CNC Turning and Milling operations. Some concepts of Robot programming are also introduced.
Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
Advancements in technology unveil a myriad of electrical and electronic breakthroughs geared towards efficiently harnessing limited resources to meet human energy demands. The optimization of hybrid solar PV panels and pumped hydro energy supply systems plays a pivotal role in utilizing natural resources effectively. This initiative not only benefits humanity but also fosters environmental sustainability. The study investigated the design optimization of these hybrid systems, focusing on understanding solar radiation patterns, identifying geographical influences on solar radiation, formulating a mathematical model for system optimization, and determining the optimal configuration of PV panels and pumped hydro storage. Through a comparative analysis approach and eight weeks of data collection, the study addressed key research questions related to solar radiation patterns and optimal system design. The findings highlighted regions with heightened solar radiation levels, showcasing substantial potential for power generation and emphasizing the system's efficiency. Optimizing system design significantly boosted power generation, promoted renewable energy utilization, and enhanced energy storage capacity. The study underscored the benefits of optimizing hybrid solar PV panels and pumped hydro energy supply systems for sustainable energy usage. Optimizing the design of solar PV panels and pumped hydro energy supply systems as examined across diverse climatic conditions in a developing country, not only enhances power generation but also improves the integration of renewable energy sources and boosts energy storage capacities, particularly beneficial for less economically prosperous regions. Additionally, the study provides valuable insights for advancing energy research in economically viable areas. Recommendations included conducting site-specific assessments, utilizing advanced modeling tools, implementing regular maintenance protocols, and enhancing communication among system components.
Democratizing Fuzzing at Scale by Abhishek Aryaabh.arya
Presented at NUS: Fuzzing and Software Security Summer School 2024
This keynote talks about the democratization of fuzzing at scale, highlighting the collaboration between open source communities, academia, and industry to advance the field of fuzzing. It delves into the history of fuzzing, the development of scalable fuzzing platforms, and the empowerment of community-driven research. The talk will further discuss recent advancements leveraging AI/ML and offer insights into the future evolution of the fuzzing landscape.
Student information management system project report ii.pdfKamal Acharya
Our project explains about the student management. This project mainly explains the various actions related to student details. This project shows some ease in adding, editing and deleting the student details. It also provides a less time consuming process for viewing, adding, editing and deleting the marks of the students.
NO1 Uk best vashikaran specialist in delhi vashikaran baba near me online vas...Amil Baba Dawood bangali
Contact with Dawood Bhai Just call on +92322-6382012 and we'll help you. We'll solve all your problems within 12 to 24 hours and with 101% guarantee and with astrology systematic. If you want to take any personal or professional advice then also you can call us on +92322-6382012 , ONLINE LOVE PROBLEM & Other all types of Daily Life Problem's.Then CALL or WHATSAPP us on +92322-6382012 and Get all these problems solutions here by Amil Baba DAWOOD BANGALI
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Quality defects in TMT Bars, Possible causes and Potential Solutions.PrashantGoswami42
Maintaining high-quality standards in the production of TMT bars is crucial for ensuring structural integrity in construction. Addressing common defects through careful monitoring, standardized processes, and advanced technology can significantly improve the quality of TMT bars. Continuous training and adherence to quality control measures will also play a pivotal role in minimizing these defects.
Explore the innovative world of trenchless pipe repair with our comprehensive guide, "The Benefits and Techniques of Trenchless Pipe Repair." This document delves into the modern methods of repairing underground pipes without the need for extensive excavation, highlighting the numerous advantages and the latest techniques used in the industry.
Learn about the cost savings, reduced environmental impact, and minimal disruption associated with trenchless technology. Discover detailed explanations of popular techniques such as pipe bursting, cured-in-place pipe (CIPP) lining, and directional drilling. Understand how these methods can be applied to various types of infrastructure, from residential plumbing to large-scale municipal systems.
Ideal for homeowners, contractors, engineers, and anyone interested in modern plumbing solutions, this guide provides valuable insights into why trenchless pipe repair is becoming the preferred choice for pipe rehabilitation. Stay informed about the latest advancements and best practices in the field.
TECHNICAL TRAINING MANUAL GENERAL FAMILIARIZATION COURSEDuvanRamosGarzon1
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Saudi Arabia stands as a titan in the global energy landscape, renowned for its abundant oil and gas resources. It's the largest exporter of petroleum and holds some of the world's most significant reserves. Let's delve into the top 10 oil and gas projects shaping Saudi Arabia's energy future in 2024.
Final project report on grocery store management system..pdfKamal Acharya
In today’s fast-changing business environment, it’s extremely important to be able to respond to client needs in the most effective and timely manner. If your customers wish to see your business online and have instant access to your products or services.
Online Grocery Store is an e-commerce website, which retails various grocery products. This project allows viewing various products available enables registered users to purchase desired products instantly using Paytm, UPI payment processor (Instant Pay) and also can place order by using Cash on Delivery (Pay Later) option. This project provides an easy access to Administrators and Managers to view orders placed using Pay Later and Instant Pay options.
In order to develop an e-commerce website, a number of Technologies must be studied and understood. These include multi-tiered architecture, server and client-side scripting techniques, implementation technologies, programming language (such as PHP, HTML, CSS, JavaScript) and MySQL relational databases. This is a project with the objective to develop a basic website where a consumer is provided with a shopping cart website and also to know about the technologies used to develop such a website.
This document will discuss each of the underlying technologies to create and implement an e- commerce website.
Event Management System Vb Net Project Report.pdfKamal Acharya
In present era, the scopes of information technology growing with a very fast .We do not see any are untouched from this industry. The scope of information technology has become wider includes: Business and industry. Household Business, Communication, Education, Entertainment, Science, Medicine, Engineering, Distance Learning, Weather Forecasting. Carrier Searching and so on.
My project named “Event Management System” is software that store and maintained all events coordinated in college. It also helpful to print related reports. My project will help to record the events coordinated by faculties with their Name, Event subject, date & details in an efficient & effective ways.
In my system we have to make a system by which a user can record all events coordinated by a particular faculty. In our proposed system some more featured are added which differs it from the existing system such as security.
3. Introduction
• Eddy current inspection is one of several methods
that use the principal of “electromagnetism” as the
basis for conducting examinations. Several other
methods such as Remote Field Testing (RFT), Flux
Leakage and Barkhausen Noise also use this
principle.
Hareesha N G, Dept of Aero Engg, DSCE 3
4. Outline
• Electromagnetic induction
• Generation of eddy currents
• Inspection applications
• Equipment utilized in eddy current inspection
Probes/Coils
Instrumentation
Reference standard
• Advantages and Limitations
Hareesha N G, Dept of Aero Engg, DSCE 4
5. Electromagnetic Induction
• Eddy currents are created through a process called
electromagnetic induction.
• When alternating current is applied to the conductor, such
as copper wire, a magnetic field develops in and around the
conductor.
• This magnetic field expands as the alternating current rises
to maximum and collapses as the current is reduced to zero.
Hareesha N G, Dept of Aero Engg, DSCE 5
6. Electromagnetic Induction (cont.)
If another electrical conductor is brought into the proximity of
this changing magnetic field, the reverse effect will occur.
Magnetic field cutting through the second conductor will cause
an “induced” current to flow in this second conductor. Eddy
currents are a form of induced currents!
Current Flow
Hareesha N G, Dept of Aero Engg, DSCE 6
7. Generation of Eddy Currents
Eddy currents are induced electrical currents that flow in a
circular path. They get their name from “eddies” that are
formed when a liquid or gas flows in a circular path around
obstacles when conditions are right.
Test Probe
Eddy Currents
Hareesha N G, Dept of Aero Engg, DSCE 7
8. Generation of Eddy Currents (cont.)
In order to generate eddy currents for an inspection a “probe”
is used. Inside the probe is a length of electrical conductor
which is formed into a coil.
Hareesha N G, Dept of Aero Engg, DSCE 8
9. Generation of Eddy Currents (cont.)
Alternating current is allowed to flow in the coil at a frequency
chosen by the technician for the type of test involved.
Hareesha N G, Dept of Aero Engg, DSCE 9
10. Generation of Eddy Currents (cont.)
A dynamic expanding and collapsing magnetic field forms in
and around the coil as the alternating current flows through
the coil.
Hareesha N G, Dept of Aero Engg, DSCE 10
11. Generation of Eddy Currents (cont.)
When an electrically conductive material is placed in the
coil’s dynamic magnetic field, electromagnetic induction will
occur and eddy currents will be induced in the material.
Hareesha N G, Dept of Aero Engg, DSCE 11
12. Generation of Eddy Currents (cont.)
Eddy currents flowing in the material will generate their own
“secondary” magnetic field which will oppose the coil’s
“primary” magnetic field.
Hareesha N G, Dept of Aero Engg, DSCE 12
13. Generation of Eddy Currents (cont.)
This entire electromagnetic induction process to produce
eddy currents may occur from several hundred to several
million times each second depending upon inspection
frequency.
Hareesha N G, Dept of Aero Engg, DSCE 13
14. Depth
Eddy Current Density
Depth
Eddy Current Density
Low Frequency
Low Conductivity
Low Permeability
High Frequency
High Conductivity
High Permeability
Standard Depth
of
Penetration
(Skin Depth)
1/e or 37 %
of surface density
Generation of Eddy Currents (cont.)
Eddy currents are strongest at the surface of the material
and decrease in strength below the surface. The depth
that the eddy currents are only 37% as strong as they are
on the surface is known as the standard depth of
penetration or skin depth. This depth changes with
probe frequency, material conductivity and permeability.
Hareesha N G, Dept of Aero Engg, DSCE 14
15. Inspection Data
• There are three characteristics of the specimen that affect
the strength of the induced eddy currents.
– The electrical conductivity of the material
– The magnetic permeability of the material
– The amount of solid material in the vicinity of the test
coil.
• Information about the strength of the eddy currents within
the specimen is determined by monitoring changes in
voltage and/or current that occur in the coil.
• The strength of the eddy currents changes the electrical
impedance (Z) of the coil.
Hareesha N G, Dept of Aero Engg, DSCE 15
16. Inspection Data (cont.)
R
~
XL
Test
Coil
Impedance (Z) in an eddy current coil is
the total opposition to current flow. In a
coil, Z is made up of resistance (R) and
inductive reactance (XL).
Definitions:
• Resistance - The opposition of current
flow, resulting in a change of electrical
energy into heat or another form of
energy.
• Inductive Reactance (XL) - Resistance to
AC current flow resulting from
electromagnetic induction in the coil.
• Impedance (Z) - The combined
opposition to current flow resulting from
inductive reactance and resistance.
In an AC coil, induction from
the magnetic field of one loop
of the coil causes a secondary
current in all other loops. The
secondary current opposes the
primary current.Hareesha N G, Dept of Aero Engg, DSCE 16
17. Inspection Applications
One of the major advantages of eddy current as an NDT tool is
the variety of inspections that can be performed. The following
slides depict some of the these capabilities.
Hareesha N G, Dept of Aero Engg, DSCE 17
18. Material Thickness Measurement
• Thickness measurements are possible with eddy current
inspection within certain limitations.
• Only a certain amount of eddy currents can form in a
given volume of material.
• Therefore, thicker materials will support more eddy
currents than thinner materials.
• The strength (amount) of eddy currents can be measured
and related to the material thickness.
Eddy Currents
Magnetic Field
From Probe
Test
Material
Hareesha N G, Dept of Aero Engg, DSCE 18
19. Material Thickness Measurement (cont.)
Eddy current inspection is often used in the aviation
industries to detect material loss due to corrosion and
erosion.
Hareesha N G, Dept of Aero Engg, DSCE 19
20. Material Thickness Measurement (cont.)
Eddy current inspection is used extensively to inspect
tubing at power generation and petrochemical facilities for
corrosion and erosion.
Hareesha N G, Dept of Aero Engg, DSCE 20
21. Crack Detection
Crack detection is one of the primary uses of eddy current
inspection. Cracks cause a disruption in the circular flow
patterns of the eddy currents and weaken their strength. This
change in strength at the crack location can be detected.
Magnetic Field
From Test Coil
Magnetic Field
From
Eddy Currents
Eddy Currents
Crack
Hareesha N G, Dept of Aero Engg, DSCE 21
22. Crack Detection (cont.)
Eddy current inspection is exceptionally well suited for the
detection of cracks, with an especially high sensitivity to
detection of surface breaking cracks.
Hareesha N G, Dept of Aero Engg, DSCE 22
23. Crack Detection (cont.)
Eddy current inspection of “bead seat” area on aircraft wheel
for cracks using special probe that conforms to the shape of the
rim.
Hareesha N G, Dept of Aero Engg, DSCE 23
24. Nonconductive Coating Measurement
Nonconductive coatings on electrically conductive substrates
can be measured very accurately with eddy current
inspection.
Conductive
Base Metal
Nonconductive
Coating
Eddy Currents
The coating displaces the eddy current probe from
the conductive base material and this weaken the
strength of the eddy currents.
This reduction in strength can be measured and
related to coating thickness.
Hareesha N G, Dept of Aero Engg, DSCE 24
25. Nonconductive Coating Measurement
(cont.)
The photo to the left shows an aircraft panel paint thickness
inspection. On the right, the display of a digital eddy current
inspection instrument shows the different signals obtained
by measuring eight different thicknesses of paint on
aluminum.
Increasing paint
thickness
Hareesha N G, Dept of Aero Engg, DSCE 25
26. Monitoring Conductivity and Permeability
Variations
Eddy current inspection is sensitive to changes in a material’s
electrical conductivity and magnetic permeability. This
“sensitivity” allows the inspection method to be used for such
inspection procedures as:
• Material Identification
• Material Sorting
• Determination of heat damage
• Cladding and plating thickness measurement
• Heat treatment monitoring
Hareesha N G, Dept of Aero Engg, DSCE 26
27. Conductivity Measurements
Boeing employees in Philadelphia were given the privilege
of evaluating the Liberty Bell for damage using NDT
techniques. Eddy current methods were used to measure
the electrical conductivity of the Bell's bronze casing at a
various points to evaluate its uniformity.
Hareesha N G, Dept of Aero Engg, DSCE 27
28. Equipment
• Equipment for eddy current inspection is very diversified.
Proper equipment selection is important if accurate
inspection data is desired for a particular application.
• As a minimum, at least three basic pieces of equipment are
needed for any eddy current examination:
– Instrumentation
– Probes
– Reference Standards
Hareesha N G, Dept of Aero Engg, DSCE 28
29. Instrumentation - Meters
Meters are typically the
simplest form of eddy
current instrumentation.
The two general
categories of meters are
digital and analog.
Hareesha N G, Dept of Aero Engg, DSCE 29
30. Digital Meters
Digital meters are typically designed to examine one specific
attribute of a test component such as conductivity or
nonconductive coating thickness. These meters tend to have
slightly higher accuracy than analog devices.
Hareesha N G, Dept of Aero Engg, DSCE 30
31. Analog Meters
Analog meters can be used for
many different inspection
applications such as crack
detection, material thickness
measurements, nonconductive
coating measurements or
conductive coating
measurements.
Hareesha N G, Dept of Aero Engg, DSCE 31
34. Eddy Current Probes (cont.)
• Probes selection is critical to acquiring adequate inspection
data.
• Several factors to consider include:
– Material penetration requirements (surface vs.
subsurface)
– Sensitivity requirements
– Type of probe connections on eddy current instrument
(many variations)
– Probe and instrument impedance matching (will probe
work with instrument)
– Probe size (smaller probes penetrate less)
– Probe type (absolute, differential, reflection or hybrid)
Hareesha N G, Dept of Aero Engg, DSCE 34
35. Eddy Current Probes (cont.)
• Due the the large variety of probes in eddy current testing
there are many different systems of classification.
• Three of the most common classifications are:
– Surface probes
– Inside Diameter (I.D.) or Bobbin Probes
– Outside Diameter (O.D.) or Encircling probes
Hareesha N G, Dept of Aero Engg, DSCE 35
36. Eddy Current Probes (cont.)
Surface probes are coils that are typically mounted close to one
end of a plastic housing. As the name implies, the technician
moves the coil end of the probe over the surface of the test
component.
Hareesha N G, Dept of Aero Engg, DSCE 36
37. Eddy Current Probes (cont.)
Some surface probes are specifically designed for crack
detection of fastener holes. These include sliding probes, ring
probes and hole probes.
Hareesha N G, Dept of Aero Engg, DSCE 37
38. Eddy Current Probes (cont.)
Surface probes can be
very small in size to allow
accessibility to confined
areas.
Finger Probe
Hareesha N G, Dept of Aero Engg, DSCE 38
39. Eddy Current Probes (cont.)
Inside Diameter (I.D.) probes, also known as bobbin probes,
are coils that are usually wound circumferentially around a
plastic housing. These probes are primarily designed for
inspection inside of tubular materials.
Hareesha N G, Dept of Aero Engg, DSCE 39
40. Eddy Current Probes (cont.)
Outside Diameter (O.D.) probes are coils that are wound the
circumference of a hollow fixture. The coil is designed such that
the test part is ran through the middle of the coil. These probes
can be used to inspect bars, rods as well as tubes.
Hareesha N G, Dept of Aero Engg, DSCE 40
42. Reference Standards (cont.)
• In order to give the eddy current inspector useful data while
conducting an inspection, signals generated from the test
specimen must be compared with known values.
• Reference standards are typically manufactured from the
same or very similar material as the test specimen.
• Many different types of standards exist for due to the variety
of eddy current inspections performed.
• The following slides provide examples of specific types of
standards.
Hareesha N G, Dept of Aero Engg, DSCE 42
43. Reference Standards (cont.)
Material thickness standards used to help determine such
things as material thinning caused by corrosion or erosion.
Hareesha N G, Dept of Aero Engg, DSCE 43
47. Advantages of Eddy Current Inspection
• Sensitive to small cracks and other defects
• Detects surface and near surface defects
• Inspection gives immediate results
• Equipment is very portable
• Method can be used for much more than flaw detection
• Minimum part preparation is required
• Test probe does not need to contact the part
• Inspects complex shapes and sizes of conductive materials
Hareesha N G, Dept of Aero Engg, DSCE 47
48. Limitations of Eddy Current Inspection
• Only conductive materials can be inspected
• Surface must be accessible to the probe
• Skill and training required is more extensive than other
techniques
• Surface finish and and roughness may interfere
• Reference standards needed for setup
• Depth of penetration is limited
• Flaws such as delaminations that lie parallel to the probe coil
winding and probe scan direction are undetectable
Hareesha N G, Dept of Aero Engg, DSCE 48
49. Glossary of Terms
• Alternating Current: electrical current that regularly reverses
direction.
• Analog: being or relating to a mechanism in which data is
represented by continuously variable physical quantities such
as a watch with hour and minute hands.
• ASME: acronym for American Society of Mechanical
Engineers. This society is highly involved in establishing and
maintaining industrial standards.
Hareesha N G, Dept of Aero Engg, DSCE 49
50. Glossary of Terms
• CRT: acronym for Cathode Ray Tube. Vacuum tube that uses
one or more electron guns for generating an image.
• Calibration: adjustment of a test systems response using
known values so that unknown quantities may be derived.
• Conductor: material capable of allowing electrical current to
flow through it.
• Discontinuity: an interruption in the physical structure of a
part. Cracks are examples of discontinuities.
• EDM: acronym for Electrical Discharge Machine.
Hareesha N G, Dept of Aero Engg, DSCE 50
51. Glossary of Terms
• EDM: acronym for Electrical Discharge Machine. Machining
technique which uses an electrode and electrical current to
remove metal. Sometimes used to prepare calibration
standards for eddy current testing.
• Electromagnetic Induction: process which creates electrical
current flow when a dynamic magnetic field is brought into
close proximity with an electrical conductor.
• Extrapolation: to project or predict unknown values from
know quantities.
Hareesha N G, Dept of Aero Engg, DSCE 51
52. Glossary of Terms
• I.A.C.S.: acronym for International Annealed Copper
Standard. Standard unit of measurement of electrical
conductivity in eddy current testing with pure annealed
copper as the standard, measuring 100% at 20 degrees
Celsius.
• Impedance Plane Diagram: A diagram that depicts the
changes in electrical impedance that occur in an eddy
current coil as test variables change.
• Multiplexing: use of a time sharing system in which a coil
is stimulated at several different frequencies one after
another for a certain amount of time. Results from each
stimulation can then be processed and displayed.
Hareesha N G, Dept of Aero Engg, DSCE 52
53. Glossary of Terms
• Permeability: the ease with which a material can be
magnetized.
• Probe: common term used in eddy current inspection that
refers to the test coil.
• RAM: acronym for Random Access Memory. Most modern
eddy current instruments have some form of memory used as
a data buffer to store information.
Hareesha N G, Dept of Aero Engg, DSCE 53