Learning Forum

[javat33489]

Hello. I need your help guys. Fluid pressure penetration does not work for me (APDL snippet in WB) I crushed the rubber and wanted to check its tightness. I have a problem with the selection of points for the initial pressure and for the supply pressure. Crushed rubber looks like this:

[javat33489]

I set the points differently and I got it have questions! the triangle on the left presses the rubber with the force method, but when I apply pressure on the rubber from the other side (fluid pressure penetration), then the triangle moves back, how to fix it? triangle moves in 10 steps, fluid pressure penetration works in step 11
gif:
png:

[javat33489]

at stage 11, fluid pressure penetration just happens why is he pushing the triangle? i need to fix it after 10 steps

[peteroznewman]

Change the load on the triangle from a force to a displacement, then at step 11, you can keep the displacement constant and it won't move when you apply the fluid pressure.
There is some APDL code to hold an object at the current displacement arrived at by a force input. I don't recall the syntax, but I know it is possible.

[javat33489]

Yes, these are the APDL options:
D, Node, Lab, VALUE1
or
DA, AREA, Lab, Value1
I just don't know how to apply them.
I chose named selection and did this DA, me_named_select, UZ, SUPPORT and i put it in the last step when force ended and fluid pressure penetration turned on, but it doesn't work.
Can you please tell me how to use it correctly?
I also have a second question. When solving with displacement, the calculation is indeed performed, but there is no rubber in the results, why?

[javat33489]

Yes, these are the APDL options:
D, Node, Lab, VALUE1
or
DA, AREA, Lab, Value1
I just don't know how to apply them.
I chose named selection and did this DA, me_named_select, UZ, SUPPORT and i put it in the last step when force ended and fluid pressure penetration turned on, but it doesn't work.
Can you please tell me how to use it correctly?
I also have a second question. When solving with displacement, the calculation is indeed performed, but there is no rubber in the results, why?

[peteroznewman]

If you open ANSYS Help in the Mechanical APDL section and look at the Command Reference for the D command, you will find this helpful paragraph where I added the bold font...
%_FIX% is a Mechanical APDL reserved table name. WhenVALUEis set to %_FIX%, the program prescribes the degree of freedom to the current relative displacement value. This option is valid for the following labels: UX, UY, UZ, ROTX, ROTY, ROTZ.
Is the rubber in the Displacement or Stress plots? You seem to be plotting a Contact Tool results which may exclude contacts if you configure it that way.

[javat33489]

Yes, everything you said is correct. I made a mistake. It works with D.
Contacts were disabled in the results, I enabled them and everything worked.

[javat33489]

I have two serious questions.
1. How to set pressure points and lines, if there are three rubbers, the second and third rubbers insure the first. If the first starts to pass pressure, the second will start to work. If the second also misses a little pressure, the third will work. How to set points and lines for start and pressure?
For one rubber, I put points and lines for fluid press penetration like this:


2. When using the APDL code, the pressure for "start" and "pressure" is always set to the same pressure number?

[javat33489]

Does anyone know the answers to the two questions? The first question is very difficult. And the second question?