where expertise comes together - since 1996

Web's Largest Portal of Nondestructive Testing (NDT)
Open Access Database (Conference Proceedings, Articles, News), Exhibition, Forum, Network

All Forum Boards
Technical Discussions >
ULTRASONICS: Shear/Longitudinal Velocity Calculation...
Career Discussions
Job Offers
Job Seeks
Classified Ads
About NDT.net
Articles & News

PBP Optel sp. z o.o.
We are searching new ways - in ultrasonic techniques - in creation of new products

1379 views
11:40 Jan-27-2009
Nathan
ULTRASONICS: Shear/Longitudinal Velocity Calculation...

Hi Guys...

What is the calculation to work out the shear wave velocity of a material, if you know the transverse velocity? I know it's approximately half, but is there a formula(e) to work it out?

Hope you can help?

Nathan

 
12:56 Jan-27-2009

Michel Couture

NDT Inspector,
consultant,
Canada,
Joined Sep 2006
804
Re: ULTRASONICS: Shear/Longitudinal Velocity Calculation... In Reply to Nathan at 11:40 Jan-27-2009 (Opening).

Nathan,

The link below will bring you the Table of Materials Properties for UT inspection. Another source is the Metal's Handbook from the American Society of Materials.

http://www.ndt-ed.org/EducationResources/CommunityCollege/Ultrasonics/Reference%20Information/UT/ut_matlprop_metals.htm

Cheerio's

 
14:38 Jan-27-2009

Thomas Vogt

R & D, - -
Guided Ultrasonics Ltd,
United Kingdom,
Joined Apr 2007
22
Re: ULTRASONICS: Shear/Longitudinal Velocity Calculation... In Reply to Nathan at 11:40 Jan-27-2009 (Opening).

Nathan,

I think you mean longitudinal instead of transverse, but nevertheless, the first thing to realize is that the shear and longitudinal velocities of a material are entirely independent. Together with the density they define the elastic properties of a material, so you cannot work one out purely from the other. You have to look it up in the table as Michel suggested.

However, you can derive a lower (theoretical) limit for the longitudinal velocity: The longitudinal velocity must be greater than the shear velocity times the square root of 2 [in a formula: v_l > v_s*sqrt(2)].

Hope this helps,
Tom

 
15:09 Jan-27-2009

Richard Freemantle

NDT Inspector, Consultant, R&D
Wavelength NDT Limited,
United Kingdom,
Joined Nov 1998
15
Re: ULTRASONICS: Shear/Longitudinal Velocity Calculation... In Reply to Thomas Vogt at 14:38 Jan-27-2009 .

Hi,

Just to add to Tom's comments, as far as I remember the longitudinal velocity can be directly related to the shear velocity provided you know the Poisson's ratio for the material. Do you have this value for the materials you are interested in ? If so I can try and dig out the equation for you !

Hope this helps,

Regards,

Richard

 
17:58 Jan-27-2009

James Barshinger

Engineering
General Electric Global Research Center,
USA,
Joined Aug 2000
8
Re: ULTRASONICS: Shear/Longitudinal Velocity Calculation... In Reply to Richard Freemantle at 15:09 Jan-27-2009 .

The equation relating shear velocity to longitudinal velocity is CT=CL*sqrt((1-2u)/(2(1-u))) where u=Poisson's ratio.

-Jim

 


© NDT.net - The Web's Largest Portal of Nondestructive Testing (NDT) ISSN 1435-4934

Open Access Database, |Conference Proceedings| |Articles| |News| |Exhibition| |Forum| |Professional Network|