where expertise comes together - since 1996 -

The Largest Open Access Portal of Nondestructive Testing (NDT)

Conference Proceedings, Articles, News, Exhibition, Forum, Network and more

where expertise comes together
- since 1996 -
492 views
Technical Discussions
John Kitzmiller
John Kitzmiller
09:55 Nov-06-2000
magnetic fields!

Does D.C. currrent pick up surface discontinuities as well as
A.C. current? If not then what is the differential?


 
 Reply 
 
dave ronson
dave ronson
02:11 Nov-06-2000
Re: magnetic fields!
: Does D.C. currrent pick up surface discontinuities as well as
: A.C. current? If not then what is the differential?

Sure it does. However, AC will find surface indications must easier since it
>is a less penetrating current. Whereas DC has the ability to penetrate the
>material much easier due to the current being Direct and not alternating as
>in AC. The alternating aspect of AC allows the particles to "dance" on the
>surface allowing the particles to attract to a discontinuity much easier.





 
 Reply 
 
Michael Trinidad
Consultant,
LMATS Pty Ltd , Australia, Joined Jan 2003, 141

Michael Trinidad

Consultant,
LMATS Pty Ltd ,
Australia,
Joined Jan 2003
141
07:15 Nov-07-2000
Re: magnetic fields!
: : Does D.C. currrent pick up surface discontinuities as well as
: : A.C. current? If not then what is the differential?

AC current passing through a conductor reverses its direction of flow at a regular frequency so that the electron movement is restricted to the surface of the conductor. The higher the frequency at which the current alternates then the greater will be the “skin effect”. As a consequence the magnetic field associated with AC flow is confined at or near the surface of the material.

DC current flows in a constant direction through a conducting material so that the electrons are moving throughout its cross section and length, although the movement is practically negligible at its centre becoming more pronounced as the surface is neared. The effect of passing DC through a conductive material is that the density of the resulting magnetic field is greatest at the surface of the conductor and becomes progressively weaker in a linear manner, as it penetrates towards the centre.

Kindest Regards


Michael Trinidad



 
 Reply 
 

Product Spotlight

Immersion systems

ScanMaster ultrasonic immersion systems are designed for high throughput, multi shift operation in a
...
n industrial or lab environment. These fully integrated systems provide various scanning configurations and incorporate conventional and phased arrays technologies to support diverse applications, such as inspection of disks, bars, shafts, billets and plates. All of ScanMaster immersion systems are built from high accuracy scanning frames allowing for scanning of complex parts and include a multi-channel ultrasonic instrument with exceptional performance. The systems are approved by all major manufacturers for C-scan inspection of jet engine forged discs. Together with a comprehensive set of software modules these flexible series of systems provide the customer with the best price performance solutions.
>

GUL Subsea Solutions - Screeening & Monitoring

To inspect new and existing subsea lines, you need proven technology and experience. GUL offers it's
...
technology to solve this challenge: GUL Subsea and gMAT Transducer Rings.
>

Research and Application Development For NDT

Acuren’s Research and Application Development specializes in the development of advanced ultraso
...
nic inspection techniques and systems for challenging inspection applications, with an emphasis on practical solutions which are field deployable. Services include manual and automated ultrasonic inspection system development, inspection technique optimization using laboratory scale studies and ultrasonic modeling (CIVA, BeamTool), preparing technical justification for technique evaluation and qualification (Probability of Detection and sizing accuracy studies), inspection/calibration/analysis procedure preparation to support field deployment of custom techniques, and development of custom imaging algorithms to support challenging inspection applications.
>

HD-CR 35 NDT Computed Radiography System

Portable high-resolution CR scanner for all radiography applications - weld testing, profile images
...
and aerospace. No matter what type of radiographic testing you are performing, the unique TreFoc Technology of the HD-CR 35 NDT imaging plate scanner always guarantees the highest image quality.
>

Share...
We use technical and analytics cookies to ensure that we will give you the best experience of our website - More Info
Accept
top
this is debug window