Inspectioneering
Inspectioneering Journal

Non-Contact Ultrasonic Testing with EMAT: Introduction to EMAT

By Borja Lopez at Innerspec Technologies, Inc.. This article appears in the March/April 2013 issue of Inspectioneering Journal
This article is part 1 of a 3-part series.
Part 1 | Part 2 | Part 3

 

This is the first in a series of three articles that will introduce Electro Magnetic Acoustic Transducer (EMAT) and its practical applications in the field of nondestructive testing (NDT).

EMAT Principles, Advantages and Disadvantages

EMAT, or Electro Magnetic Acoustic Transducer, is an Ultrasonic Testing (UT) technique that generates the sound in the part inspected instead of the transducer.

An EMAT generates ultrasonic waves into a test object using electromagnetic induction with two interacting magnetic fields. A relatively high frequency (RF) field generated by electrical coils interacts with a low frequency or static field generated by magnets to generate a Lorentz force in a manner similar to an electric motor. This disturbance is transferred to the lattice of the material, producing an elastic wave. In a reciprocal process, the interaction of elastic waves in the presence of a magnetic field induces currents in the receiving EMAT coil circuit. For ferromagnetic conductors, magnetostriction produces additional stresses that can enhance the signals to much higher levels than could be obtained by the Lorentz force alone.

This content is available to registered users and subscribers

Register today to unlock this article for free.

Create your free account and get access to:

  • Unlock one premium article of your choosing per month
  • Exclusive online content, videos, and downloads
  • Insightful and actionable webinars
GET STARTED
Interested in unlimited access? VIEW OUR SUBSCRIPTION OPTIONS

Current subscribers and registered users can log in now.


Comments and Discussion

Posted by Jim Rentoul on May 6, 2013
Interested if it has the ability to... Log in or register to read the rest of this comment.

Add a Comment

Please log in or register to participate in comments and discussions.

Interested in equipment reliability & integrity? Sign up for weekly updates.

Inspectioneering Journal

Explore over 20 years of articles written by our team of subject matter experts.

Company Directory

Find relevant products, services, and technologies.

Job Postings

Discover job opportunities that match your skillset.

Case Studies

Learn from the experience of others in the industry.

Event Calendar

Find upcoming conferences, training sessions, online events, and more.

Industry News

Stay up-to-date with the latest inspection and asset integrity management news.

Blog

Read short articles and insights authored by industry experts.

Acronyms

Commonly used asset integrity management and inspection acronyms.

Asset Intelligence Reports

Download brief primers on various asset integrity management topics.

Videos

Watch educational and informative videos directly related to your profession.

Expert Interviews

Inspectioneering's archive of interviews with industry subject matter experts.