×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

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!
  • Students Click Here

*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

Jobs

Torsion Spring Creep

Torsion Spring Creep

Torsion Spring Creep

(OP)
Hello Forum,

I'm using a rectangular wire torsion spring in a safety device to indicate applied torque.  The assembly environment is outdoors and cycles in lifetime < 500.

min tensile strength (not min yield) = 256 ksi
max design stress = 167 ksi
preload stress = 110 ksi

I just wanted to verify some things I've heard with the bright people on this forum.

1. Creep (relaxation) for torsion springs <5%
2. Max design stress should be < 75% of min Tensile stress

Thank you

RE: Torsion Spring Creep

Hi xr4titis

Provided the ratio of mean coil dia to wire dia is less than 8 then 75% of UTS as a design stress is used particularly if its a spring that operates only infrequently.
I would use a design stress of abou 40-50% personally.
Creep will depend on material used and whether its at an elevated temperature, at room temp your 5% is reasonable.

desertfox

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!


Resources