Abaqus Orthotropic material

[Harryboy]

Hi,

Working on the implementation of a orthotropic Kirshhoff material in ABAQUS EXPLICITE using finite strains.
When the result is compared to the result from ABAQUS *ELASTIC,type=ENGINEERING CONSTANTS the result differ significantly. I am aware of the shortcomings of the Kirshhoff material, but I cant realy figure out why the difference is that large.

So, my question to you all:
Do anyone know what type of model ABAQUS is using for the card *ELASTIC,type=ENGINEERING CONSTANTS??
My guess is that it is a hypo elastic model based on the Green-Naghdi rate, since the Jaumann rate wont do the trick.

Best regards
Harrysboy

[Jorgen]

Harrysboy,

:arrow: How do you define a Kirchhoff material?
:arrow: The *Elastic, type=engineering constants material is an anisotropic elastic material model. I am not sure of the details of how ABAQUS has implemented that model, but why do you think that a elastic material would need to be implemented using a rate equation?

- Jorgen

[Tompa]

Hi
I think that the model used by ABAQUS for *elastic is only valid for small strains, cf. *ELASTIC in the Keyword reference manual (v6.6) and 17.2.1 Linear elastic behavior in the Analysis User's Manual.
The rate equations used by ABAQUS is reported in 1.5.3 Stress rates in the theory manual (v6.6). Jaumann rate for built in constitutive models for continuum elements and Green-Naghdi for structual elements.

Take care
Tompa