USDFLD subroutine ABAQUS 1

[Shufen]

How does ABAQUS interpolate the values of a material property based on the variation of multiple field variables?

Hi fellow researchers, I would like to clear something in ABAQUS regarding the manner in which ABAQUS interpolates a material property that has been defined to vary according to a finite number of field variables using the user subroutine USDFLD. Let’s say I have a model where I am defining the Young’s modulus E varying according to 3 field variables F1, F2 and F3 as the following:

E poisson’s ration Field 1 Field 2 Field 3
50 GPa 0.3 1 0 0
30 GPa 0.3 0 1 0
20 GPa 0.3 0 0 1

In temperature dependence case, I understand the value of E at a particular intermediate temperature would have been considered by linear interpolation. However, in the above case how will ABAQUS consider the value of E at a point where F1=0.5, F2=0.3 and F3=0.2?

 

[akabarten]

Hi,

Your example is incorrect and interpolation can not be done in this case.

From Abaqus documentation (21.1.2 Material data definition, Interpolation of material data)

When material properties depend on several variables, the variation of the properties with respect to the first variable must be given at fixed values of the other variables, in ascending values of the second variable, then of the third variable, and so on. The data must always be ordered so that the independent variables are given increasing values.

For three field variables with values in range from 0 to 2 we must define lines:

**
**
50 0 0 0
30 1 0 0
20 2 0 0
**
50 0 1 0
30 1 1 0
20 2 1 0
**
50 0 2 0
30 1 2 0
20 2 2 0
**------
50 0 0 1
30 1 0 1
20 2 0 1
**
50 0 1 1
30 1 1 1
20 2 1 1
**
50 0 2 1
30 1 2 1
20 2 2 1
**------
50 0 0 2
30 1 0 2
20 2 0 2
**
50 0 1 2
30 1 1 2
20 2 1 2
**
50 0 2 2
30 1 2 2
20 2 2 2
**

In first column you can define any E value to describe dependencies you need.
Now interpolation is possible.

Regards,
Bartosz

VIM filetype plugin for Abaqus

https://github.com/gradzikb/vim-abaqus

 

[Shufen]

Wow,
this was really helpful. Now it makes sense. Thank you so much. By the way, there is a link attachment redirecting me to github for a plugin. I have never used this plugin. Is the plugin useful? Thank you again.

Regards
Shufen

 

[akabarten]

Hi,

It you prefer to work directly with abaqus inputdecks in text editor the plugin make work easier.
However it is for VIM text editor so you have to know it.

Regards,
Bartosz

VIM filetype plugin for Abaqus

https://github.com/gradzikb/vim-abaqus