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Simple VUMAT/UMAT
Hi all,
I was wondering if anyone could provide some guidance on
writing the following VUMAT /UMAT or have anything similar that I can modify;
I would like to define a material for ABAQUS that has the
following properties; the material is elastic and isotropic and does not have
any inelasticity performance;
- Elastic properties to be
defined are; Modulus of elasticity (E), Poisson’s ratio (v) and an
ultimate TENSION strain value. - The material is isotropic
and elastic. Under any state of applied loading, any finite element that
reaches the specified ultimate tensile strain value must be considered
failed. - At this stage, ABAQUS is
expected to continue the analysis without the element that has failed but
with the consideration that there is a geometrical change in the structure
modelled (meaning the element does not strain further or take any stress.
It is not accepted to set the modulus of elasticity to zero only). The
analysis continues in search of another element that would reach the
tension strain value and remove it. - This process continues
until the modelled structure fails or cannot take any more loading.
I have attached a stress-strain graph of the material in TENSION.
Any help would be very much appreciated.
Many thanks
Hussam
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Simple VUMAT/UMAT with failure
Hello
get inspired by
http://imechanica.org/node/12361
In Abaqus Standard:
Note MODEL CHANGE at the end of that thread. I don't know how to use MODEL CHANGE in Abaqus Standard for your purpose. If you have to combine it with a UMAT: for re-writing elasticity in Abaqus Standard using UMAT refer to
http://imechanica.org/files/Writing User Subroutines with ABAQUS.pdf
In Abaqus Explicit:
In VUMAT make the state variable for failure detection equal to the ultimate tension strain value.
Get back to me if you don't find an example for elasticity in Abaqus Explicit using VUMAT.
------------------------------------------
Ruhr-University
Bochum
Germany
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Dear Frank,
Thanks for your reply. I have joined the Google group you
proposed, I noticed your generous contribution to helping others there too.
However, many of the links to websites didn’t work on my PC
for some reason including the one here in your message. http://imechanica.org/files/Writing
I would like your opinion on to how to practice writing
UMAT/VUMAT subroutines as I am a beginner. Is there a starting step that you
would recommend because I don’t understand what and how commands are written in
the script.
I didn’t find the manual helpful for this purpose; don’t
know if you would agree?
If you also could provide a VUMAT/UMAT on elasticity, it would
be great. I could then understand its components and apply a state variable
accordingly.
I realise that this is quite a bit to ask for but your help
is very much appreciated.
Many thanks again
Hussam Nasreddin