Learning Forum

[javat33489]

Hi all.

I want to make a calculation where I will squeeze two rubbers. These are two rubber rings placed on a pipe, with a steel ring between them. This is an axisymmetric problem. It is planned that the entire structure will be under water. I will squeeze two rubbers and my task is to understand whether all the water will be squeezed out between them or whether it will remain because water is an incompressible liquid. Which module is best to do this in? In static analysis or transient analysis? Give your advice please?

[dlooman]

I don't understand the picture, but this would certainly be a static analysis.  If the water is contained within a closed surface it can be represented by the hydrostatic fluid elements (hsfld241).  APDL verification manual test vm209 is an example.  This could become a complicated model to set up, so as a first step you could analyze the rubber, pipe and ring without the water.

[javat33489]

In real life, these rubbers will be submerged in water. That is, these rubbers are mounted on a pipe, and this structure is located in an even larger pipe, which will be filled with water. I need to understand when compressed whether the water will remain between the rubbers or whether it will be squeezed out completely.

[dlooman]

Also, it appears you have axial half symmetry in addition to axisymmetry.  That will simplify the model and make it more stable.

[dlooman]

So there is water between the rubber and the ring that you want to squeeze out or do you want to squeeze out the water labeled water with a circle around it in your sketch?  If the water is not fully enclosed or if the volume of the rubber doesn't change when it is compressed then your model may not need to include the water.  Just the rubber and contact between the pipe elements.

[javat33489]

When two rubbers are compressed, water remains in the yellow circle. I want to see if it will squeeze out when the rubber is completely compressed

[dlooman]

It would be very difficult or impossible to get that much deformation in the rubber bodies.  Even if you could, there wouldn't be a way to model the fluid trapped in that small triangle.  

[javat33489]

It seems you didn't understand anything. This is an already working structure in the well. I just want to know if the water will cool down. Rubber is compressed with a force of 6 tons and then a pressure of 30 MPa is applied to it. This is a very durable rubber. But it’s not clear to me whether the water will remain between the rubber or whether the compressed rubber will completely squeeze it out. In which module is it better to solve this?

[javat33489]

It will roughly look like this:

Water remains between the rubber bands. What will happen to her? If you press even harder will it stay there? I need to find out.

[dlooman]

Your image shows that axial symmetry could be used.  It looks to me like pushing harder will increase the sealing pressure, but won't increase the pressure in the cavity very much at all.  I think the fluid is trapped.  

[javat33489]

And I need to solve this. In which module is it better to solve this in order to see it?

[dlooman]

It would be a Static Structural analysis in Mechanical.

[javat33489]

What about water? Can I draw it around the rubber and add the material to the engineering date? and that is all?

[dlooman]

I don't see a way to model the water for a couple reasons.  First, water isn't a structural material and doesn't have any shear stiffness.  Second, it appears you need to specify its geometry in the deformed cavity created by the rubber bodies.  There's no way to do that.   

[javat33489]

My task is to model with water. I myself know perfectly well that you can simply compress rubber in a static setting.

[dlooman]

I think it would be best to create a new post for someone else to take.  I don't know how to do it.