clemenc
Materials
- Aug 11, 2014
- 1
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!
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!