Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here




Does anyone have experience in the use of magnetostrictive properties to clamp mechanical parts?

We would like to clamp a 0.5" diameter shaft and ideally use the strain of the material to release the shaft when a magnetic field is applied. Effectively, it would act like an energise to release solenoid.

Any thoughts welcome.

RE: terfenol/magnetostrictive

Check out the mechanical properties of the material to make sure it can handle the expected loads - Terfenol is somewhat brittle.

Terfenol needs to be partially magnetized before it reaches a region where the strain response is linear to the applied magnetic field.  Hopefully that will not be a problem in your application.

There are a bunch of good people at Etrema, where one of their core products is Terfenol:


RE: terfenol/magnetostrictive

Thanks for the response.
In our application, with reference to the brittle issue....I don't think think there will be many shock loads on the material itself.
My main question I suppose is whether a ring of the material can be used so it moves in the radial direction. In theory, without the field applied it would be holding the shaft and once the shaft needs to be removed the applied field would increases the internal diameter by enough to free it. At 1200ppm strain the clearances are mechanically feasible. However, most of the examples on the etrema site relate to expansion along the axis and contraction perpendicular so what we would like may not be possible although they do say the axis can be oriented based on the application(at a cost I'm sure).

I'm based in the UK and am in comms with etrema through the only uk distributor but it is a slow process, I just thought I'd pick some brains on the forums to get as much info as possible.

Thanks again.

RE: terfenol/magnetostrictive

Wow! Interesting application!

Unfortunately, radial expansion would be challenging.  Not only does the Terfenol need to be oriented radially, the applied magnetic field would also have to be radially oriented.  Producing a radial magnetic field is possible, but a challenge unto itself.

Since you are in the UK, you might want to contact Dr. David Jiles at the Wolfson Centre of Magnetics at Cardiff University.  He did quite a bit of modeling/development work with Terfenol in the early 1990's.

RE: terfenol/magnetostrictive

Using Terfenol-D is not simple you need to compress the Terfenol using a spring and activate a coil around the Terfenol bar. To my understanding in case of a ring the coil will be a toroidal coil around the ring so the inside of the coil will be inside the ring and will not allow a contact between the ring and the shaft. Add to this that the compressing force should be inward to the center of the ring.

If the shaft movement is rotation I think you may use a coil wrapped spring clutch/brake wrapped around the shaft and released by a solenoid

RE: terfenol/magnetostrictive

Maybe you could use a system of rods along the axis of the shaft and small cams or dogs to actually engage.  This would be less compact, but the geometries would be much more manageable.

= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close