changing material properties in abaqus
changing material properties in abaqus
(OP)
Hi All,
I am going to model density that is changing through the thickness for graded plates.
Before, I wrote UMAT to model variation of elastic modulus through the thickness and I solved my bending problem. But at this moments I want to add density to solve vibration as well.
I dont know how can I modell that. I mean if I define the density as a function of z in UMAT how abaqus define density in its solution. because in UMAT, elastic modulus can be related to stress and strain but there is no calling for density.
I would greatly appreciate if you help me.
please see the attached file for UMAT for variation of elastic modulus for bending analysis
I am going to model density that is changing through the thickness for graded plates.
Before, I wrote UMAT to model variation of elastic modulus through the thickness and I solved my bending problem. But at this moments I want to add density to solve vibration as well.
I dont know how can I modell that. I mean if I define the density as a function of z in UMAT how abaqus define density in its solution. because in UMAT, elastic modulus can be related to stress and strain but there is no calling for density.
I would greatly appreciate if you help me.
please see the attached file for UMAT for variation of elastic modulus for bending analysis





RE: changing material properties in abaqus
I have no experience with UMAT but I agree density is not a part of UMAT definition.
Base on Abaqus documentation it looks like density is independent to UMAT.
Abaqus Analysis User's Manual, 26.7.1 User-defined mechanical material behavior, Material constants
Just add *DENSITY keyword into your *MATERIAL definition and then you can use field variable and/or distribution:
http://www.eng-tips.com/viewthread.cfm?qid=407697
Regards,
Bartosz
VIM filetype plugin for Abaqus
https://github.com/gradzikb/vim-abaqus
RE: changing material properties in abaqus
many thanks foe your help.
I wrote USDFLD for E and density based on your previous comments in the following thread:
http://www.eng-tips.com/viewthread.cfm?qid=385982
but I gave different frequency compared with by-hand solution. I think it could related my BC.
actually, BC is simply supported. I am thankful if you let me know how can model simply supported plate correctly?
Regards
RE: changing material properties in abaqus
RE: changing material properties in abaqus
Good point, I did not know this.
Thanks,
Bartosz
VIM filetype plugin for Abaqus
https://github.com/gradzikb/vim-abaqus
RE: changing material properties in abaqus
what is the meaning of that? """Just to mention that again: It is not possible to change the density during the simulation.""
You mean density cannot define as a field variable in the USDFLD? what do you think about the following thread:
http://www.eng-tips.com/viewthread.cfm?qid=385982
they used density in USDFLD and I don't know why you said it is not possible.
then, what should I do to model density variation?
thanks
RE: changing material properties in abaqus
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RE: changing material properties in abaqus
The manual is also pretty clear about that.
RE: changing material properties in abaqus
RE: changing material properties in abaqus