×
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

Spring analysis

Spring analysis

Spring analysis

(OP)
Hi,

I am trying to do a simple static analysis with 4 springs connected between two blocks. The stiffness of each spring is 1e5 N/m. The bottom block is fixed and top block is pulled with 10 kN. So using simple F=KX,I am suppose to get 25mm of displacement for top block. But I am getting 25.31mm. For such a simple analysis what could be the possible error ? I don't think mesh convergence might be an issue (?) as spring is single element. I am applying 10kN as a uniform pressure on top surface of top block. Element is Spring2, with fixed direction as axis.

Also for a perfectly vertical pull, I am noticing a rotation of top block. I am attaching the picture here. Can someone kindly suggest where I might be doing wrong.

Thanks in advance.

Regards
Pat

RE: Spring analysis

Are these blocks perfectly rigid ?

RE: Spring analysis

(OP)
Thank you PamCrash. Yes, when compared to spring stiffness blocks are rigid. I defined them as 3D deformable bodies with steel properties - E = 200GPa. I made some quick calculation to check what can be elongation in both blocks due to applied 10kN load. It works out to be 0.3 and 1.6 micron in small and big block respectively. When compared to error of 0.3mm, these are very small. So there is something else which is causing this error and also the rotation of top block as it is being pulled up(as shown in diagram in earlier post). I think springs definition may not be correct, though I can't find any error in that. You may see the way I defined springs in the attached figure.

Many thanks for your help.

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