I am using fluid cavity capability for simulation of a water-filled container with Abaqus-Static-Standard. The container has an initial pressure and is been surrounded by another solid layer with UMAT Material property. I need to simulate the reaction of outer layer according to the inside pressure of the container. However, inside pressure of the container fall to zero at the first increments and simulation continue with zero pressure! I am sure that defined fluid cavity is completely closed, as there is no “Not enclosed” warning in *.dat file.
Could anyone please give me some idea for modeling this simulation?
Thanks in advance
The initial fluid pressure shall be defined, otherwise, it's zero as I assume (Abaqus manual 27.2.1)
*INITIAL CONDITIONS, TYPE=FLUID PRESSURE
If your minimum value is small, then the cavity stiffness can go to infinity - numerical issue, try to define a minimum value not smaller than the initial volume e.g.
FLUID CAVITY, MINIMUM VOLUME=INITIAL VOLUME
Source:
https://abaqus-docs.mit.edu/2017/English/SIMACAEANLRefMap/simaanl-c-fluidcavities.htm
It could be that after the initial step, in the deformed configuration, the reference node of the cavity lies outside the reference volume?
Regarding the warning "not enclosed", a user describes that he solved the error when replacing membrane elements with solid elements
https://www.eng-tips.com/viewthread.cfm?qid=384267
I think that the internal fluid pressure applied at first stage or phase not as a boundary condition.
Did you set-up the ambient pressure as it is said in the manual as well:
-AMBIENT PRESSURE
Set this parameter equal to the magnitude of the ambient pressure. For a pneumatic fluid, the ambient pressure will typically be atmospheric pressure.
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