×
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

Problem with Invariant input to ABAQUS Material Routine UANISOHYPER_INV

Problem with Invariant input to ABAQUS Material Routine UANISOHYPER_INV

Problem with Invariant input to ABAQUS Material Routine UANISOHYPER_INV

(OP)
Hi everybody,

for learning purpose, i try to re-implement the known HGO-Model in Abaqus using UANISOHYPER_INV, before trying something more difficult. This is the first time i use the invariant subroutine for anisotropic hyperelastic materials but I have some experience with the UANISOHYPER_STRAIN.

What I did:
- I made a little test-model of 8 cubes, each one consisting of only one Element (C3D8).
- 4 of them are associated with the original HGO material and 4 with my homemade material, so i can compare the resulting material behavior optically as a first evaluation.
- The 4 cubes of one particular material have one preferred fiber orientation each (represented through vectors (1,0,0), (0,1,0), (0,0,1), (1,1,1) ).
- the BCs hold the cubes in position while the constrained nodes can shift in the corresponding plane.
- the 4 top (max z) nodes of each cube are moved half the side lentgh down in z-direction

--> Please see the screenshot attached (i hope it works) <--


When i run the model, no errors occur, but the results look pretty strange:
- the cubes with my material simply shrink (same amount in all directions!!), but generate no stress in response, while the cubes with original HGO behave like expected.
- while debugging with VS2005, my routine seems to calculate everything as it should, i compared several calculations with my Results of Mathematica
- strangely the input values for the invariants Ainv() always stay the same with the exception of shrinking Ainv(3) = volume ratio J.


Anyone here with an idea, what i could have missed??


Thanks in advance for every idea!

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